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as one of the wonders of africa , and one of the most unique religious buildings in the world , the great mosque of djenné , in present-day mali , is also the greatest achievement of sudano-sahelian architecture ( sudano-sahelian refers to the sudanian and sahel grassland of west africa ) . it is also the largest mud-built structure in the world . we experience its monumentality from afar as it dwarfs the city of djenné . imagine arriving at the towering mosque from the neighborhoods of low-rise adobe houses that comprise the city . djenné was founded between 800 and 1250 c.e. , and it flourished as a great center of commerce , learning , and islam , which had been practiced from the beginning of the 13th century . soon thereafter , the great mosque became one of the most important buildings in town primarily because it became a political symbol for local residents and for colonial powers like the french who took control of mali in 1892 . over the centuries , the great mosque has become the epicenter of the religious and cultural life of mali , and the community of djenné . it is also the site of a unique annual festival called the crepissage de la grand mosquée ( plastering of the great mosque ) . the great mosque that we see today is its third reconstruction , completed in 1907 . according to legend , the original great mosque was probably erected in the 13th century , when king koi konboro—djenné ’ s twenty-sixth ruler and its first muslim sultan ( king ) —decided to use local materials and traditional design techniques to build a place of muslim worship in town . king konboro ’ s successors and the town ’ s rulers added two towers to the mosque and surrounded the main building with a wall . the mosque compound continued to expand over the centuries , and by the 16th century , popular accounts claimed half of djenné ’ s population could fit in the mosque ’ s galleries . the first great mosque and its reconstructions some of the earliest european writings on the first great mosque came from the french explorer rené caillié who wrote in detail about the structure in his travelogue j_ournal d ’ un voyage a temboctou et à jenné_ ( journal of a voyage to timbuktu and djenné ) . caillié traveled to djenné in 1827 , and he was the only european to see the monument before it fell into ruin . in his travelogue , he wrote that the building was already in bad repair from the lack of upkeep . in the sahel—the transitional zone between the sahara and the humid savannas to the south—adobe and mud buildings such as the great mosque require periodic and often annual re-plastering . if re-plastering does not occur , the exteriors of the structures melt in the rainy season . based on caillié ’ s description , his visit likely coincided with a period when the mosque had not been re-plastered for several years , and multiple rainy seasons had probably washed away all the plaster and worn the mud-brick . a second mosque built between 1834 and 1836 replaced the original and damaged building described by caillié . we can see evidence of this construction in drawings by the french journalist felix dubois . in 1896 , three years after the french conquest of the city , dubois published a plan of the mosque based on his survey of the ruins . the structure drawn by dubois ( left ) was more compact than the one that is seen today . based on the drawings , the second construction of the great mosque was more massive than the first and defined by its weightiness . it also featured a series of low minaret towers and equidistant pillar supports . the present and third iteration of the great mosque was completed in 1907 , and some scholars argue that the french constructed it during their period of occupation of the city starting in 1892 . however , no colonial documents support this theory . new scholarship supports the idea that the mason ’ s guild of djenné built the current mosque with the help of forced laborers from villages of adjacent regions , brought in by french colonial authorities . to accompany and motivate workers , musicians were provided who played drums and flutes . workers included masons who mixed tons of mud , sand , rice-husks , and water and formed the bricks that shape the current structure . the great mosque today the great mosque that we see today is rectilinear in plan and is partly enclosed by an exterior wall . an earthen roof covers the building , which is supported by monumental pillars . the roof has several holes covered by terra-cotta lids ( above ) , which provide its interior spaces with fresh air even during the hottest days . the façade of the great mosque includes three minarets and a series of engaged columns that together create a rhythmic effect ( below ) . at the top of the pillars are conical extensions with ostrich eggs placed at the very top—symbol of fertility and purity in the malian region . timber beams throughout the exterior are both decorative and structural . these elements also function as scaffolding for the re-plastering of the mosque during the annual festival of the crepissage . compared to images and descriptions of the previous buildings , the present great mosque includes several innovations such as a special court reserved for women and a principal entrance with earthen pillars , that signal the graves of two local religious leaders . re-plastering the mosque during the annual festival of the crepissage de la grand mosquée , the entire city contributes to the re-plastering of the mosque ’ s exterior by kneading into it a mud plaster made from a mixture of butter and fine clay from the alluvial soil of the nearby niger and bani rivers . the men of the community usually take up the task of mixing the construction material . as in the past , musicians entertain them during their labors , while women provide water for the mixture . elders also contribute through their presence on site , by sitting on terrace walls and giving advice . mixing work and play , young boys sing , run , and dash everywhere . over the years djenné ’ s inhabitants have withstood repeated attempts to change the character of their exceptional mosque and the nature of the annual festival . for instance , some have tried to suppress the playing of music during the crepissage , and foreign muslim investors have also offered to rebuild the mosque in concrete and tile its current sand floor . djenné ’ s community has unrelentingly striven to maintain its cultural heritage and the unique character of the great mosque . in 1988 , the tenacious effort led to the designation of the site and the entire town of djenné as a world heritage site by unesco . essay by dr. elisa dainese additional resources : old towns of djenné ( from unesco )
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workers included masons who mixed tons of mud , sand , rice-husks , and water and formed the bricks that shape the current structure . the great mosque today the great mosque that we see today is rectilinear in plan and is partly enclosed by an exterior wall . an earthen roof covers the building , which is supported by monumental pillars .
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so , what are the dimensions of this huge mosque ?
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as one of the wonders of africa , and one of the most unique religious buildings in the world , the great mosque of djenné , in present-day mali , is also the greatest achievement of sudano-sahelian architecture ( sudano-sahelian refers to the sudanian and sahel grassland of west africa ) . it is also the largest mud-built structure in the world . we experience its monumentality from afar as it dwarfs the city of djenné . imagine arriving at the towering mosque from the neighborhoods of low-rise adobe houses that comprise the city . djenné was founded between 800 and 1250 c.e. , and it flourished as a great center of commerce , learning , and islam , which had been practiced from the beginning of the 13th century . soon thereafter , the great mosque became one of the most important buildings in town primarily because it became a political symbol for local residents and for colonial powers like the french who took control of mali in 1892 . over the centuries , the great mosque has become the epicenter of the religious and cultural life of mali , and the community of djenné . it is also the site of a unique annual festival called the crepissage de la grand mosquée ( plastering of the great mosque ) . the great mosque that we see today is its third reconstruction , completed in 1907 . according to legend , the original great mosque was probably erected in the 13th century , when king koi konboro—djenné ’ s twenty-sixth ruler and its first muslim sultan ( king ) —decided to use local materials and traditional design techniques to build a place of muslim worship in town . king konboro ’ s successors and the town ’ s rulers added two towers to the mosque and surrounded the main building with a wall . the mosque compound continued to expand over the centuries , and by the 16th century , popular accounts claimed half of djenné ’ s population could fit in the mosque ’ s galleries . the first great mosque and its reconstructions some of the earliest european writings on the first great mosque came from the french explorer rené caillié who wrote in detail about the structure in his travelogue j_ournal d ’ un voyage a temboctou et à jenné_ ( journal of a voyage to timbuktu and djenné ) . caillié traveled to djenné in 1827 , and he was the only european to see the monument before it fell into ruin . in his travelogue , he wrote that the building was already in bad repair from the lack of upkeep . in the sahel—the transitional zone between the sahara and the humid savannas to the south—adobe and mud buildings such as the great mosque require periodic and often annual re-plastering . if re-plastering does not occur , the exteriors of the structures melt in the rainy season . based on caillié ’ s description , his visit likely coincided with a period when the mosque had not been re-plastered for several years , and multiple rainy seasons had probably washed away all the plaster and worn the mud-brick . a second mosque built between 1834 and 1836 replaced the original and damaged building described by caillié . we can see evidence of this construction in drawings by the french journalist felix dubois . in 1896 , three years after the french conquest of the city , dubois published a plan of the mosque based on his survey of the ruins . the structure drawn by dubois ( left ) was more compact than the one that is seen today . based on the drawings , the second construction of the great mosque was more massive than the first and defined by its weightiness . it also featured a series of low minaret towers and equidistant pillar supports . the present and third iteration of the great mosque was completed in 1907 , and some scholars argue that the french constructed it during their period of occupation of the city starting in 1892 . however , no colonial documents support this theory . new scholarship supports the idea that the mason ’ s guild of djenné built the current mosque with the help of forced laborers from villages of adjacent regions , brought in by french colonial authorities . to accompany and motivate workers , musicians were provided who played drums and flutes . workers included masons who mixed tons of mud , sand , rice-husks , and water and formed the bricks that shape the current structure . the great mosque today the great mosque that we see today is rectilinear in plan and is partly enclosed by an exterior wall . an earthen roof covers the building , which is supported by monumental pillars . the roof has several holes covered by terra-cotta lids ( above ) , which provide its interior spaces with fresh air even during the hottest days . the façade of the great mosque includes three minarets and a series of engaged columns that together create a rhythmic effect ( below ) . at the top of the pillars are conical extensions with ostrich eggs placed at the very top—symbol of fertility and purity in the malian region . timber beams throughout the exterior are both decorative and structural . these elements also function as scaffolding for the re-plastering of the mosque during the annual festival of the crepissage . compared to images and descriptions of the previous buildings , the present great mosque includes several innovations such as a special court reserved for women and a principal entrance with earthen pillars , that signal the graves of two local religious leaders . re-plastering the mosque during the annual festival of the crepissage de la grand mosquée , the entire city contributes to the re-plastering of the mosque ’ s exterior by kneading into it a mud plaster made from a mixture of butter and fine clay from the alluvial soil of the nearby niger and bani rivers . the men of the community usually take up the task of mixing the construction material . as in the past , musicians entertain them during their labors , while women provide water for the mixture . elders also contribute through their presence on site , by sitting on terrace walls and giving advice . mixing work and play , young boys sing , run , and dash everywhere . over the years djenné ’ s inhabitants have withstood repeated attempts to change the character of their exceptional mosque and the nature of the annual festival . for instance , some have tried to suppress the playing of music during the crepissage , and foreign muslim investors have also offered to rebuild the mosque in concrete and tile its current sand floor . djenné ’ s community has unrelentingly striven to maintain its cultural heritage and the unique character of the great mosque . in 1988 , the tenacious effort led to the designation of the site and the entire town of djenné as a world heritage site by unesco . essay by dr. elisa dainese additional resources : old towns of djenné ( from unesco )
|
over the centuries , the great mosque has become the epicenter of the religious and cultural life of mali , and the community of djenné . it is also the site of a unique annual festival called the crepissage de la grand mosquée ( plastering of the great mosque ) . the great mosque that we see today is its third reconstruction , completed in 1907 .
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when does the annual festival take place ?
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as one of the wonders of africa , and one of the most unique religious buildings in the world , the great mosque of djenné , in present-day mali , is also the greatest achievement of sudano-sahelian architecture ( sudano-sahelian refers to the sudanian and sahel grassland of west africa ) . it is also the largest mud-built structure in the world . we experience its monumentality from afar as it dwarfs the city of djenné . imagine arriving at the towering mosque from the neighborhoods of low-rise adobe houses that comprise the city . djenné was founded between 800 and 1250 c.e. , and it flourished as a great center of commerce , learning , and islam , which had been practiced from the beginning of the 13th century . soon thereafter , the great mosque became one of the most important buildings in town primarily because it became a political symbol for local residents and for colonial powers like the french who took control of mali in 1892 . over the centuries , the great mosque has become the epicenter of the religious and cultural life of mali , and the community of djenné . it is also the site of a unique annual festival called the crepissage de la grand mosquée ( plastering of the great mosque ) . the great mosque that we see today is its third reconstruction , completed in 1907 . according to legend , the original great mosque was probably erected in the 13th century , when king koi konboro—djenné ’ s twenty-sixth ruler and its first muslim sultan ( king ) —decided to use local materials and traditional design techniques to build a place of muslim worship in town . king konboro ’ s successors and the town ’ s rulers added two towers to the mosque and surrounded the main building with a wall . the mosque compound continued to expand over the centuries , and by the 16th century , popular accounts claimed half of djenné ’ s population could fit in the mosque ’ s galleries . the first great mosque and its reconstructions some of the earliest european writings on the first great mosque came from the french explorer rené caillié who wrote in detail about the structure in his travelogue j_ournal d ’ un voyage a temboctou et à jenné_ ( journal of a voyage to timbuktu and djenné ) . caillié traveled to djenné in 1827 , and he was the only european to see the monument before it fell into ruin . in his travelogue , he wrote that the building was already in bad repair from the lack of upkeep . in the sahel—the transitional zone between the sahara and the humid savannas to the south—adobe and mud buildings such as the great mosque require periodic and often annual re-plastering . if re-plastering does not occur , the exteriors of the structures melt in the rainy season . based on caillié ’ s description , his visit likely coincided with a period when the mosque had not been re-plastered for several years , and multiple rainy seasons had probably washed away all the plaster and worn the mud-brick . a second mosque built between 1834 and 1836 replaced the original and damaged building described by caillié . we can see evidence of this construction in drawings by the french journalist felix dubois . in 1896 , three years after the french conquest of the city , dubois published a plan of the mosque based on his survey of the ruins . the structure drawn by dubois ( left ) was more compact than the one that is seen today . based on the drawings , the second construction of the great mosque was more massive than the first and defined by its weightiness . it also featured a series of low minaret towers and equidistant pillar supports . the present and third iteration of the great mosque was completed in 1907 , and some scholars argue that the french constructed it during their period of occupation of the city starting in 1892 . however , no colonial documents support this theory . new scholarship supports the idea that the mason ’ s guild of djenné built the current mosque with the help of forced laborers from villages of adjacent regions , brought in by french colonial authorities . to accompany and motivate workers , musicians were provided who played drums and flutes . workers included masons who mixed tons of mud , sand , rice-husks , and water and formed the bricks that shape the current structure . the great mosque today the great mosque that we see today is rectilinear in plan and is partly enclosed by an exterior wall . an earthen roof covers the building , which is supported by monumental pillars . the roof has several holes covered by terra-cotta lids ( above ) , which provide its interior spaces with fresh air even during the hottest days . the façade of the great mosque includes three minarets and a series of engaged columns that together create a rhythmic effect ( below ) . at the top of the pillars are conical extensions with ostrich eggs placed at the very top—symbol of fertility and purity in the malian region . timber beams throughout the exterior are both decorative and structural . these elements also function as scaffolding for the re-plastering of the mosque during the annual festival of the crepissage . compared to images and descriptions of the previous buildings , the present great mosque includes several innovations such as a special court reserved for women and a principal entrance with earthen pillars , that signal the graves of two local religious leaders . re-plastering the mosque during the annual festival of the crepissage de la grand mosquée , the entire city contributes to the re-plastering of the mosque ’ s exterior by kneading into it a mud plaster made from a mixture of butter and fine clay from the alluvial soil of the nearby niger and bani rivers . the men of the community usually take up the task of mixing the construction material . as in the past , musicians entertain them during their labors , while women provide water for the mixture . elders also contribute through their presence on site , by sitting on terrace walls and giving advice . mixing work and play , young boys sing , run , and dash everywhere . over the years djenné ’ s inhabitants have withstood repeated attempts to change the character of their exceptional mosque and the nature of the annual festival . for instance , some have tried to suppress the playing of music during the crepissage , and foreign muslim investors have also offered to rebuild the mosque in concrete and tile its current sand floor . djenné ’ s community has unrelentingly striven to maintain its cultural heritage and the unique character of the great mosque . in 1988 , the tenacious effort led to the designation of the site and the entire town of djenné as a world heritage site by unesco . essay by dr. elisa dainese additional resources : old towns of djenné ( from unesco )
|
workers included masons who mixed tons of mud , sand , rice-husks , and water and formed the bricks that shape the current structure . the great mosque today the great mosque that we see today is rectilinear in plan and is partly enclosed by an exterior wall . an earthen roof covers the building , which is supported by monumental pillars .
|
in the third paragraph of the section `` the great mosque today , '' the author mentions `` a special court reserved for women '' - are women only allowed to enter this one section of the mosque ?
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as one of the wonders of africa , and one of the most unique religious buildings in the world , the great mosque of djenné , in present-day mali , is also the greatest achievement of sudano-sahelian architecture ( sudano-sahelian refers to the sudanian and sahel grassland of west africa ) . it is also the largest mud-built structure in the world . we experience its monumentality from afar as it dwarfs the city of djenné . imagine arriving at the towering mosque from the neighborhoods of low-rise adobe houses that comprise the city . djenné was founded between 800 and 1250 c.e. , and it flourished as a great center of commerce , learning , and islam , which had been practiced from the beginning of the 13th century . soon thereafter , the great mosque became one of the most important buildings in town primarily because it became a political symbol for local residents and for colonial powers like the french who took control of mali in 1892 . over the centuries , the great mosque has become the epicenter of the religious and cultural life of mali , and the community of djenné . it is also the site of a unique annual festival called the crepissage de la grand mosquée ( plastering of the great mosque ) . the great mosque that we see today is its third reconstruction , completed in 1907 . according to legend , the original great mosque was probably erected in the 13th century , when king koi konboro—djenné ’ s twenty-sixth ruler and its first muslim sultan ( king ) —decided to use local materials and traditional design techniques to build a place of muslim worship in town . king konboro ’ s successors and the town ’ s rulers added two towers to the mosque and surrounded the main building with a wall . the mosque compound continued to expand over the centuries , and by the 16th century , popular accounts claimed half of djenné ’ s population could fit in the mosque ’ s galleries . the first great mosque and its reconstructions some of the earliest european writings on the first great mosque came from the french explorer rené caillié who wrote in detail about the structure in his travelogue j_ournal d ’ un voyage a temboctou et à jenné_ ( journal of a voyage to timbuktu and djenné ) . caillié traveled to djenné in 1827 , and he was the only european to see the monument before it fell into ruin . in his travelogue , he wrote that the building was already in bad repair from the lack of upkeep . in the sahel—the transitional zone between the sahara and the humid savannas to the south—adobe and mud buildings such as the great mosque require periodic and often annual re-plastering . if re-plastering does not occur , the exteriors of the structures melt in the rainy season . based on caillié ’ s description , his visit likely coincided with a period when the mosque had not been re-plastered for several years , and multiple rainy seasons had probably washed away all the plaster and worn the mud-brick . a second mosque built between 1834 and 1836 replaced the original and damaged building described by caillié . we can see evidence of this construction in drawings by the french journalist felix dubois . in 1896 , three years after the french conquest of the city , dubois published a plan of the mosque based on his survey of the ruins . the structure drawn by dubois ( left ) was more compact than the one that is seen today . based on the drawings , the second construction of the great mosque was more massive than the first and defined by its weightiness . it also featured a series of low minaret towers and equidistant pillar supports . the present and third iteration of the great mosque was completed in 1907 , and some scholars argue that the french constructed it during their period of occupation of the city starting in 1892 . however , no colonial documents support this theory . new scholarship supports the idea that the mason ’ s guild of djenné built the current mosque with the help of forced laborers from villages of adjacent regions , brought in by french colonial authorities . to accompany and motivate workers , musicians were provided who played drums and flutes . workers included masons who mixed tons of mud , sand , rice-husks , and water and formed the bricks that shape the current structure . the great mosque today the great mosque that we see today is rectilinear in plan and is partly enclosed by an exterior wall . an earthen roof covers the building , which is supported by monumental pillars . the roof has several holes covered by terra-cotta lids ( above ) , which provide its interior spaces with fresh air even during the hottest days . the façade of the great mosque includes three minarets and a series of engaged columns that together create a rhythmic effect ( below ) . at the top of the pillars are conical extensions with ostrich eggs placed at the very top—symbol of fertility and purity in the malian region . timber beams throughout the exterior are both decorative and structural . these elements also function as scaffolding for the re-plastering of the mosque during the annual festival of the crepissage . compared to images and descriptions of the previous buildings , the present great mosque includes several innovations such as a special court reserved for women and a principal entrance with earthen pillars , that signal the graves of two local religious leaders . re-plastering the mosque during the annual festival of the crepissage de la grand mosquée , the entire city contributes to the re-plastering of the mosque ’ s exterior by kneading into it a mud plaster made from a mixture of butter and fine clay from the alluvial soil of the nearby niger and bani rivers . the men of the community usually take up the task of mixing the construction material . as in the past , musicians entertain them during their labors , while women provide water for the mixture . elders also contribute through their presence on site , by sitting on terrace walls and giving advice . mixing work and play , young boys sing , run , and dash everywhere . over the years djenné ’ s inhabitants have withstood repeated attempts to change the character of their exceptional mosque and the nature of the annual festival . for instance , some have tried to suppress the playing of music during the crepissage , and foreign muslim investors have also offered to rebuild the mosque in concrete and tile its current sand floor . djenné ’ s community has unrelentingly striven to maintain its cultural heritage and the unique character of the great mosque . in 1988 , the tenacious effort led to the designation of the site and the entire town of djenné as a world heritage site by unesco . essay by dr. elisa dainese additional resources : old towns of djenné ( from unesco )
|
based on caillié ’ s description , his visit likely coincided with a period when the mosque had not been re-plastered for several years , and multiple rainy seasons had probably washed away all the plaster and worn the mud-brick . a second mosque built between 1834 and 1836 replaced the original and damaged building described by caillié . we can see evidence of this construction in drawings by the french journalist felix dubois .
|
who was involved in building the mosque ?
|
as one of the wonders of africa , and one of the most unique religious buildings in the world , the great mosque of djenné , in present-day mali , is also the greatest achievement of sudano-sahelian architecture ( sudano-sahelian refers to the sudanian and sahel grassland of west africa ) . it is also the largest mud-built structure in the world . we experience its monumentality from afar as it dwarfs the city of djenné . imagine arriving at the towering mosque from the neighborhoods of low-rise adobe houses that comprise the city . djenné was founded between 800 and 1250 c.e. , and it flourished as a great center of commerce , learning , and islam , which had been practiced from the beginning of the 13th century . soon thereafter , the great mosque became one of the most important buildings in town primarily because it became a political symbol for local residents and for colonial powers like the french who took control of mali in 1892 . over the centuries , the great mosque has become the epicenter of the religious and cultural life of mali , and the community of djenné . it is also the site of a unique annual festival called the crepissage de la grand mosquée ( plastering of the great mosque ) . the great mosque that we see today is its third reconstruction , completed in 1907 . according to legend , the original great mosque was probably erected in the 13th century , when king koi konboro—djenné ’ s twenty-sixth ruler and its first muslim sultan ( king ) —decided to use local materials and traditional design techniques to build a place of muslim worship in town . king konboro ’ s successors and the town ’ s rulers added two towers to the mosque and surrounded the main building with a wall . the mosque compound continued to expand over the centuries , and by the 16th century , popular accounts claimed half of djenné ’ s population could fit in the mosque ’ s galleries . the first great mosque and its reconstructions some of the earliest european writings on the first great mosque came from the french explorer rené caillié who wrote in detail about the structure in his travelogue j_ournal d ’ un voyage a temboctou et à jenné_ ( journal of a voyage to timbuktu and djenné ) . caillié traveled to djenné in 1827 , and he was the only european to see the monument before it fell into ruin . in his travelogue , he wrote that the building was already in bad repair from the lack of upkeep . in the sahel—the transitional zone between the sahara and the humid savannas to the south—adobe and mud buildings such as the great mosque require periodic and often annual re-plastering . if re-plastering does not occur , the exteriors of the structures melt in the rainy season . based on caillié ’ s description , his visit likely coincided with a period when the mosque had not been re-plastered for several years , and multiple rainy seasons had probably washed away all the plaster and worn the mud-brick . a second mosque built between 1834 and 1836 replaced the original and damaged building described by caillié . we can see evidence of this construction in drawings by the french journalist felix dubois . in 1896 , three years after the french conquest of the city , dubois published a plan of the mosque based on his survey of the ruins . the structure drawn by dubois ( left ) was more compact than the one that is seen today . based on the drawings , the second construction of the great mosque was more massive than the first and defined by its weightiness . it also featured a series of low minaret towers and equidistant pillar supports . the present and third iteration of the great mosque was completed in 1907 , and some scholars argue that the french constructed it during their period of occupation of the city starting in 1892 . however , no colonial documents support this theory . new scholarship supports the idea that the mason ’ s guild of djenné built the current mosque with the help of forced laborers from villages of adjacent regions , brought in by french colonial authorities . to accompany and motivate workers , musicians were provided who played drums and flutes . workers included masons who mixed tons of mud , sand , rice-husks , and water and formed the bricks that shape the current structure . the great mosque today the great mosque that we see today is rectilinear in plan and is partly enclosed by an exterior wall . an earthen roof covers the building , which is supported by monumental pillars . the roof has several holes covered by terra-cotta lids ( above ) , which provide its interior spaces with fresh air even during the hottest days . the façade of the great mosque includes three minarets and a series of engaged columns that together create a rhythmic effect ( below ) . at the top of the pillars are conical extensions with ostrich eggs placed at the very top—symbol of fertility and purity in the malian region . timber beams throughout the exterior are both decorative and structural . these elements also function as scaffolding for the re-plastering of the mosque during the annual festival of the crepissage . compared to images and descriptions of the previous buildings , the present great mosque includes several innovations such as a special court reserved for women and a principal entrance with earthen pillars , that signal the graves of two local religious leaders . re-plastering the mosque during the annual festival of the crepissage de la grand mosquée , the entire city contributes to the re-plastering of the mosque ’ s exterior by kneading into it a mud plaster made from a mixture of butter and fine clay from the alluvial soil of the nearby niger and bani rivers . the men of the community usually take up the task of mixing the construction material . as in the past , musicians entertain them during their labors , while women provide water for the mixture . elders also contribute through their presence on site , by sitting on terrace walls and giving advice . mixing work and play , young boys sing , run , and dash everywhere . over the years djenné ’ s inhabitants have withstood repeated attempts to change the character of their exceptional mosque and the nature of the annual festival . for instance , some have tried to suppress the playing of music during the crepissage , and foreign muslim investors have also offered to rebuild the mosque in concrete and tile its current sand floor . djenné ’ s community has unrelentingly striven to maintain its cultural heritage and the unique character of the great mosque . in 1988 , the tenacious effort led to the designation of the site and the entire town of djenné as a world heritage site by unesco . essay by dr. elisa dainese additional resources : old towns of djenné ( from unesco )
|
based on caillié ’ s description , his visit likely coincided with a period when the mosque had not been re-plastered for several years , and multiple rainy seasons had probably washed away all the plaster and worn the mud-brick . a second mosque built between 1834 and 1836 replaced the original and damaged building described by caillié . we can see evidence of this construction in drawings by the french journalist felix dubois .
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in the second picture , are the people walking towards the mosque muslims ?
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as one of the wonders of africa , and one of the most unique religious buildings in the world , the great mosque of djenné , in present-day mali , is also the greatest achievement of sudano-sahelian architecture ( sudano-sahelian refers to the sudanian and sahel grassland of west africa ) . it is also the largest mud-built structure in the world . we experience its monumentality from afar as it dwarfs the city of djenné . imagine arriving at the towering mosque from the neighborhoods of low-rise adobe houses that comprise the city . djenné was founded between 800 and 1250 c.e. , and it flourished as a great center of commerce , learning , and islam , which had been practiced from the beginning of the 13th century . soon thereafter , the great mosque became one of the most important buildings in town primarily because it became a political symbol for local residents and for colonial powers like the french who took control of mali in 1892 . over the centuries , the great mosque has become the epicenter of the religious and cultural life of mali , and the community of djenné . it is also the site of a unique annual festival called the crepissage de la grand mosquée ( plastering of the great mosque ) . the great mosque that we see today is its third reconstruction , completed in 1907 . according to legend , the original great mosque was probably erected in the 13th century , when king koi konboro—djenné ’ s twenty-sixth ruler and its first muslim sultan ( king ) —decided to use local materials and traditional design techniques to build a place of muslim worship in town . king konboro ’ s successors and the town ’ s rulers added two towers to the mosque and surrounded the main building with a wall . the mosque compound continued to expand over the centuries , and by the 16th century , popular accounts claimed half of djenné ’ s population could fit in the mosque ’ s galleries . the first great mosque and its reconstructions some of the earliest european writings on the first great mosque came from the french explorer rené caillié who wrote in detail about the structure in his travelogue j_ournal d ’ un voyage a temboctou et à jenné_ ( journal of a voyage to timbuktu and djenné ) . caillié traveled to djenné in 1827 , and he was the only european to see the monument before it fell into ruin . in his travelogue , he wrote that the building was already in bad repair from the lack of upkeep . in the sahel—the transitional zone between the sahara and the humid savannas to the south—adobe and mud buildings such as the great mosque require periodic and often annual re-plastering . if re-plastering does not occur , the exteriors of the structures melt in the rainy season . based on caillié ’ s description , his visit likely coincided with a period when the mosque had not been re-plastered for several years , and multiple rainy seasons had probably washed away all the plaster and worn the mud-brick . a second mosque built between 1834 and 1836 replaced the original and damaged building described by caillié . we can see evidence of this construction in drawings by the french journalist felix dubois . in 1896 , three years after the french conquest of the city , dubois published a plan of the mosque based on his survey of the ruins . the structure drawn by dubois ( left ) was more compact than the one that is seen today . based on the drawings , the second construction of the great mosque was more massive than the first and defined by its weightiness . it also featured a series of low minaret towers and equidistant pillar supports . the present and third iteration of the great mosque was completed in 1907 , and some scholars argue that the french constructed it during their period of occupation of the city starting in 1892 . however , no colonial documents support this theory . new scholarship supports the idea that the mason ’ s guild of djenné built the current mosque with the help of forced laborers from villages of adjacent regions , brought in by french colonial authorities . to accompany and motivate workers , musicians were provided who played drums and flutes . workers included masons who mixed tons of mud , sand , rice-husks , and water and formed the bricks that shape the current structure . the great mosque today the great mosque that we see today is rectilinear in plan and is partly enclosed by an exterior wall . an earthen roof covers the building , which is supported by monumental pillars . the roof has several holes covered by terra-cotta lids ( above ) , which provide its interior spaces with fresh air even during the hottest days . the façade of the great mosque includes three minarets and a series of engaged columns that together create a rhythmic effect ( below ) . at the top of the pillars are conical extensions with ostrich eggs placed at the very top—symbol of fertility and purity in the malian region . timber beams throughout the exterior are both decorative and structural . these elements also function as scaffolding for the re-plastering of the mosque during the annual festival of the crepissage . compared to images and descriptions of the previous buildings , the present great mosque includes several innovations such as a special court reserved for women and a principal entrance with earthen pillars , that signal the graves of two local religious leaders . re-plastering the mosque during the annual festival of the crepissage de la grand mosquée , the entire city contributes to the re-plastering of the mosque ’ s exterior by kneading into it a mud plaster made from a mixture of butter and fine clay from the alluvial soil of the nearby niger and bani rivers . the men of the community usually take up the task of mixing the construction material . as in the past , musicians entertain them during their labors , while women provide water for the mixture . elders also contribute through their presence on site , by sitting on terrace walls and giving advice . mixing work and play , young boys sing , run , and dash everywhere . over the years djenné ’ s inhabitants have withstood repeated attempts to change the character of their exceptional mosque and the nature of the annual festival . for instance , some have tried to suppress the playing of music during the crepissage , and foreign muslim investors have also offered to rebuild the mosque in concrete and tile its current sand floor . djenné ’ s community has unrelentingly striven to maintain its cultural heritage and the unique character of the great mosque . in 1988 , the tenacious effort led to the designation of the site and the entire town of djenné as a world heritage site by unesco . essay by dr. elisa dainese additional resources : old towns of djenné ( from unesco )
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workers included masons who mixed tons of mud , sand , rice-husks , and water and formed the bricks that shape the current structure . the great mosque today the great mosque that we see today is rectilinear in plan and is partly enclosed by an exterior wall . an earthen roof covers the building , which is supported by monumental pillars .
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how many people did it take to build the mosque ?
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most traditional religions in africa have developed at the local level and are unique to a particular society . common elements include a belief in a creator god , who is rarely if ever represented in art and directly approached by worshipers . instead , the supreme deity is petitioned through intermediaries , or lesser spirits . these spirits may be related to the natural world and have control over powerful natural phenomena . for instance , nwantantay masks used by the bwa of burkina faso represent various flying spirits that inhabit the natural world and can offer protection . these flying spirits are believed to take physical form as insects or water fowl . in guinea , baga beliefs describe local water spirits , called niniganné , associated with both wealth and danger that take symbolic form as snakes . nature spirits , appealed to by baule diviners in côte d ’ ivoire for spiritual insights , are conceived of as grotesque beings associated with untamed wilderness ( example here ) . other spirits represent founding ancestors , whose activities are described in stories about the creation of the world and the beginnings of human life and agriculture . the dogon of mali recount their genesis story with reference to nommo , a primordial being who guided an ark with the eight original ancestors from heaven to populate the earth ( top of page ) . also in mali , bamana agricultural ceremonies invoke ci wara , the half man and half antelope credited with introducing agriculture to humanity ( above ) . the original ancestors in senufo ( côte d ’ ivoire ) belief are represented by a monumental pair of male and female figures exemplifying an ideal social unit ( example below ) . the category of spirits believed to be most accessible to humans is that of recently deceased ancestors , who can intercede on behalf of the living community . among the akan in ghana , ancestors are commemorated by terracotta sculptures that , when placed in a sacred grove near the cemetery , serve as a focal point for funeral rites and a point of contact with the deceased ( example here ) . fang societies preserved the bones of important deceased individuals in bark containers in the belief that their relics held great spiritual power ( example here ) . in many large states , a living king and leader may be regarded as divine as well . in the kingdom of benin , in today ’ s nigeria , the oba historically was considered semi-divine and therefore constituted the political and spiritual focus of the kingdom ( example here ) . christianity in africa in addition to indigenous religions at a local level , other religions are also practiced throughout africa . christianity has existed in egypt and northern africa since the second century . the ethiopian orthodox church was established in the fourth century by king ezana , who adopted christianity as the state religion ( example here ) . in the late fifteenth century , christianity was introduced into sub- saharan africa by portuguese explorers and traders . although most african cultures did not adopt the religion , the kongo king afonso mvemba a nzinga established christianity as the state religion in the early sixteenth century ( example here ) . during the colonial period , christianity gained converts throughout the continent . islam came to egypt after 640 , then spread below the sahara in the eighth and ninth centuries through traders and scholars . on the east coast , arab and persian colonizers introduced islam beginning in the eighth century . although the acceptance of islam or christianity sometimes precluded the practice of traditional religions , in many cases they coexisted or were incorporated into preexisting beliefs . the adoption of islam and christianity also led to the abandonment of many earlier forms of artistic expression . religious practice in africa centers on a desire to engage the spiritual world in the interests of social stability and well-being . annual rites of renewal among the bwa , for example , are designed to seek the continued goodwill of nature spirits ( example here ) . political leaders also seek religious guidance to ensure the success of their reign . fon kings , for example , referenced a divination process known as fa , which predicted the nature and character of their reign ( example here ) . personal misfortune , such as illness , death , or barrenness , or community crises , including war or drought , are also cause to petition the spirits for guidance and assistance . art objects are employed as vehicles for spiritual communication in diverse ways . some are created for use in an altar or shrine and may receive sacrificial offerings . the dogon of mali , for example , show gratitude to the ancestors by offering pieces of meat in a monumental container presented to the family altar ( below ) . in the kingdom of benin ( nigeria ) , cast brass heads commemorating deceased kings are placed on royal ancestral altars , where they serve as a point of contact with the king ’ s royal ancestors ( above ) . other objects are used by diviners to attract and tap into spiritual forces . the dazzling beauty of an expertly carved baule figure sculpture lures a nature spirit into inhabiting the sculpture , thereby aiding a diviner ’ s work ( example here ) . such objects themselves are often not inherently powerful but must be activated through ritual offerings or by a knowledgeable religious specialist . fon diviners empower figurative sculptures called bocio with organic substances that ensure their client ’ s health and well-being ( left ) . similarly , kongo ritual objects known as nkisi derive their potency from various substances , both organic and man-made , added to a carved figure by a ritual specialist ( example here ) . the unseen forces of nature or the spiritual world are called upon to serve a variety of purposes , including communicating with the spirits , honoring ancestors , healing sickness , or reinforcing societal standards , through masked performances . masquerades involve the active participation of dancers , musicians , and even the audience , in addition to the masked dancer , who serves as the vehicle through which these invisible powers become manifest ( a masquerade is a social gathering of persons wearing masks and often fantastical costumes ) . by donning a mask and its associated costume , the dancer transcends his own identity and is transformed into a powerful spiritual being . among the dogon , masks are worn at dama , a collective funerary rite for men whose goal is to ensure safe passage of the deceased ’ s spirit to the world of the ancestors ( example here ) . masked performances by members of the bamana komo association convey knowledge of their history , beliefs , and rituals to initiated members ( example here ) . the massive sculpted headdress known as d ’ mba among the baga is seen as a symbol of cultural reinvention and appears on various occasions marking personal and communal growth ( example here ) . among the mende and their neighbors , masquerades of the sande society encourage and celebrate young female initiates and offer a model of feminine beauty and spiritual power ( example here ) by dr. christa clarke , for the metropolitan museum of art , new york © 2006 the metropolitan museum of art , new york ( by permission ) . additional resources : african art on the metropolitan museum of art ’ s heilbrunn timeline of art history art and life in africa ( university of iowa ) seated ( dogon ) couple at the metropolitan museum of art headdress : male antelope ( ci wara ) at the metropolitan museum of art male and female poro altar figures ( ndeo ) at the metropolitan museum of art ritual vessel ( aduno koro ) : horse at the metropolitan museum of art crucifix from the democratic republic of congo at the metropolitan museum of art art and oracle : african art and rituals of divination ( ebook from the metropolitan museum of art )
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in the late fifteenth century , christianity was introduced into sub- saharan africa by portuguese explorers and traders . although most african cultures did not adopt the religion , the kongo king afonso mvemba a nzinga established christianity as the state religion in the early sixteenth century ( example here ) . during the colonial period , christianity gained converts throughout the continent .
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what 's up with every religion having an afterlife ?
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“ all art constantly aspires to the condition of music ” – walter pater a troubled past when he wrote that statement , i doubt that walter pater had in mind the veritable rock opera that is the ghent altarpiece , now housed in the cathedral of st. bavo , ghent ( in present-day belgium ) . from its singing , costumed , organ-pumping chorister angels to its gospel-choir legions of saints , soldiers , prophets and martyrs , to its central panel depicting the adoration of the mystic lamb—is there any other fifteenth-century altarpiece that even comes close in spirit to the 1970s theatrical excesses of rock operas like jesus christ superstar ? in the film the monuments men , george clooney solemnly pronounces the ghent altarpiece to be the most important work of art in the western tradition . as humbug as that may sound , it is certainly important , as much for its unparalleled technique as for what the painting has meant historically . removed from its place in the cathedral of ghent by napoleon ( well , the main panels , anyway ) and then by german occupying forces during world war i , the panels were returned and reassembled , only to be taken again by the nazis in 1942 and stored carelessly in a salt mine for the duration of the second world war . the altarpiece was rescued by allied art experts in 1945 ( below ) who reassembled , cleaned and restored the panels , which had lost much of their varnish and suffered some surface abrasion . since that time , the altarpiece has seldom failed to be in some process of constant condition monitoring ( as t.s . eliot would say “ like a patient etherized upon a table ” ) or some kind of reconstruction or conservation—a kind of cultural-historical exercise in trying to perfect the past . the latest campaign of study , restoration and renewal has gone on since 2009 , much of it carried out in front of the crowds at saint bavo 's cathedral and at the museum of fine arts in ghent . astonishingly , given its many trials and tribulations , the altarpiece has weathered well . only one of the original 12 panels ( 8 of which are part of the hinged shutter apparatus , and therefore painted on both sides ) , has been lost . in 1934 the panels depicting st. john the baptist , and another depicting the just judges were stolen from the church . the john the baptist panel was recovered . the just judges panel ( on the lower left when the altarpiece is open—see image at the top of the page ) was replaced with a modern copy during the 1945 restoration . the other panels have all survived , although there is some lingering disagreement about whether they are now reassembled in their original configuration , given the many times the altarpiece has been taken apart . a pixilated present the getty foundation in los angeles has funded the recent campaign to conserve the ghent altarpiece , an effort being led by belgium 's royal institute for cultural heritage . a painstaking photographic enlargement is captured in 100 million pixels on the `` closer to van eyck '' website . there , one can probe the impenetrably gorgeous enamel-like surface of van eyck ’ s greatest masterpiece , and gaze astonished at his virtuosic accomplishments . a moveable feast the altarpiece itself is a visual '' moveable feast , '' made up of 12 panels that fold against themselves ( see the video above ) . it is like frozen theatre , and when open , reveals a spiritual guidebook to divine revelation . in its basic configuration , the rather austere , largely monochromatic outer panels ( above ) —which show the kneeling patrons and statues of prophets and glimpses into orderly rooms ; are grounded in the material and sensible terrestrial world , in which gabriel appears to mary at the moment of the annunciation . but when the altarpiece is opened , we travel , accompanied by prophets on foot and princes on horseback , saints and martyrs and more angels , to the brilliantly-colored heart of the scene depicting the adoration of the mystic lamb ( below ) . it is as if the makers of the wizard of oz derived their inspiration for a black-and-white kansas and a technicolor oz , from ghent . byzantine influences the adoration of the mystic lamb ( above ) is presided over by the figure of god ( the bearded jesus with crown and scepter , below ) . * this figure can also be read as christ pantokrator ( one of the many names for god in the jewish tradition and , in the bible , an appellation used only by john the baptist to describe god ) , flanked by separate panels of john the baptist to the right and the virgin mary to the left ( below ) . the combination of these three figures reminds us of a byzantine image type—the deësis ( from the greek , “ prayer ” ) , which shows the intercession of the virgin mary and st. john the baptist for the salvation of our souls , the heavenly interview at the moment of the last judgement ( an example of a byzantine deësis , byzantine art refers to art from the byzantine or eastern roman empire ) . in the adoration of the mystic lamb ( left detail ) , the sacrifice of the lamb , symbol of christ ’ s slaughter for our salvation , is similarly byzantine in origin . the inner panels are painted in the bold and dynamic naturalistic style for which the artist jan van eyck is justifiably famous . in all of its positions , the ghent altarpiece is a vision of the visionary . it alludes not only to sight but to sound—musical angels accompanying the elaborate orchestration of the whole . its appeal to the senses threatens to overwhelm the intellectual apprehension of its content . the artists according to an inscription , written on two silver strips mounted on the rear of the two donor panels , and only discovered in 1823 , the altarpiece was painted by the brothers jan and hubert van eyck : the painter hubert van eyck , than whom none was greater , began this work . jan [ his brother ] , second in art , completed it at the request of joos [ jodocus ] vijd on the sixth of may [ 1432 ] . he begs you by means of this verse to take care of what came into being . because jan van eyck is seen as the far more famous of the two brothers , the reference to jan as `` second in art '' has raised a few eyebrows among art historians , eager to assign the lion ’ s share of the work to young jan. my own undergraduate professor postulated that what the inscription means is that hubert was responsible for the actual construction of the altarpiece , which was later largely painted by jan—a not unusual sequence of events in a fifteenth-century workshop ( building polyptych , or many-paneled , altarpieces required construction knowledge , and painting them required an entirely different expertise ) . hubert died in 1426 , and the altarpiece was finished in 1432 , so jan probably took over the contract hubert signed with the patron of the work , judocos vijd ( sometimes spelled `` vijdt '' ) , which also would have made jan literally `` second in art . '' we know jan to have been an exquisite painter of miniatures who worked for the dukes of burgundy , and there are many aspects of the work here consistent with the detailed work of a manuscript illuminator , but there are also some important differences , particularly in scale . the relatively large size of the panels pushed jan to new heights of virtuosity as a master of light ; directional light , saturation , the softest scale of illuminations in the gradation of shadow , the construction of space through light and shade , symphonies of reflection and refraction alive in a world of textured surfaces—literally , the light of the world . here , for the first time on such a scale , is a picture of the completely natural world saturated by the light of god—the perfect intermingling of divine illumination with the created world—and all described in paint . van eyck creates a world within the painting as substantial and real as the world outside the painting . say what you will about brunelleschi and masaccio and linear perspective in florence , without the subtlety of oil paint , their works look like mathematical equations beside the painted world of the ghent altarpiece . the patrons like most renaissance patrons , jodocus vijd was a wealthy merchant who sought to expiate the sin of being too fond of money by spending some of it on creating a monument to god . an influential citizen of ghent , vijd commissioned the altarpiece for the church dedicated to st. john the baptist ( now the cathedral of st. bavo ) in his home city as a means of saving his soul while simultaneously celebrating his wealth . vijd was warden of the church of st. john and assistant burgomeister of ghent , and he had a rich aristocratic wife , so he had plenty of money to commission the van eyck brothers . it is uncertain the extent to which he influenced the iconography of the overall work , but he obviously spared no expense . the distinctive faces of jodocus vijd and elizabeth borluut ( the husband and wife patrons ) are each shown in three-quarter view ( left and below ) . they kneel in the traditional donor positions , with their hands clasped in prayer , facing each other and gazing vaguely toward the central panels . undoubtedly , contemporaries would have recognized them taking pride of place in such an important civic church , and although the immediacy of their presence would fade with time , their identities as the donors of the work remain intact . the altarpiece , closed it is best to start in the smallest and most constricted stage of the altarpiece in its closed position . the kneeling donors are depicted on the outer extremes , separated by simulated statues of two standing saints painted in grisaille ( shades of grey ) —st . john the baptist and st. john the evangelist ( above ) . in the register above is a depiction of the annunciation—this is the moment when the archangel gabriel announces to mary that she will be the mother of christ ( above ) . figures of the angel and mary are found on the outer edges of the panels . the holy spirit hovers over mary . the two contiguous scenes between them are pure genre scenes ( scenes of everyday life ) . beside gabriel , a window opens onto a view of buildings in ghent ( left ) , beside the virgin , a recessed niche holds a silver tray , a small hanging silver pitcher and a linen towel neatly hanging from a rack ( below ) . these items are consistent with iconography of the period that uses domestic objects as a means of expressing the purity of the virgin . we are drawn most deeply into the center of the altarpiece ( achieved without mathematically calculated perspective—you can tell because the floor appears to tilt upward ) , toward the mystery within . at the top of the gabriel panel , beneath a shallow rounded arch , is the old testament prophet zacharias , father of john the baptist ; and above the virgin , we see the old testament prophet micah , who predicted the birth of the messiah in bethlehem . the two central panels in this upper register depict the erythraean and cumaean sibyls ( sibyls are female figures from ancient greece and rome who prophesied the future ) . these four figures are all messengers of the incarnation and sacrifice of christ ( michelangelo painted these prophets and sibyls in the sistine chapel , and more ) . the altarpiece , open opened , the altarpiece is divided into two horizontal registers . the deësis ( the virgin mary , christ/god , * and st. john the baptist ) panels are flanked on either side by choirs of heavenly angels and , on the outermost panels at each side , adam and eve . god ’ s first human creatures are therefore the parenthetical figures of this upper register and the figures that necessitate the salvation scene below ) . their literal marginalization—at the edges of the altarpiece—is indicative of their state of sin . eve holds the forbidden fruit and covers her genitals . opposite her , adam assumes the classical pose of the so-called `` modest venus , '' one arm across his chest , the other covering his genitals ( a rather peculiar pose for a male figure to assume ) . adam and eve 's sin in the garden of eden ( the fall of man ) is , of course , the reason for all that occurs below in the panel known as the adoration of the mystic lamb—the full salvation play , complete with sacrificial lamb , a symbolic representation of christ ( from gospel of john : '' the next day john saw jesus coming toward him , and said , 'behold ! the lamb of god who takes away the sin of the world ! ' '' —john 1:29 ) . from the outer edges of the lower panels , crowds converge towards the altar in the center , presenting a unified field across the five panels , overcoming the gothic division of the frame . from the left come figures known as the just judges and the soldiers of christ , on horseback , arrayed in glittering armor and armed with swords of justice , followed by the judges wearing opulent and various finery . from the right come the saints and the prophets , chief among them the giant ( and apocryphal ) st. christopher ( below ) , the male saints suitably dressed in simple tunics and robes in sober earth tones . these crowds approach the central panel . where are they all going ? they ’ re going to witness the sacrifice of the mystic lamb . the adoration of the mystic lamb the key panel of the altarpiece , the adoration of the mystic lamb ( detail above ) , depicts a large meadow , dotted with flowers , at the centre of which are two key structures—in the foreground is a lovely octagonal stone fountain , with a tall central pedestal from which spring multiple cascades of water . in the background , on a direct axis with the fountain , is an altar with a lamb standing on it . the head of the strangely alert lamb is surrounded by a glowing nimbus ( a halo , here depicted as golden rays ) . in the sky above , the dove of the holy spirit descends in its own pulsating nimbus of light from which radiate long , golden spires that touch the angels and the ground . behind the altar , in the distance , are trees and one tall tower , punctuated by windows ( left ) . still further back on the blue horizon are distant mountains ; the setting is a paradisiacal landscape for the re-enactment of the sacrifice of christ . what is the relationship between the altar , the sacrifice of the lamb , and the foreground fountain ? the mystic lamb is the lamb of god—the sacrificial lamb—a symbol of christ and christ ’ s death . the lamb on the altar is equivalent to the crucifixion of christ , made explicit by the juxtaposition of the lamb with the cross held by the angel . other angels behind the altar hold the instruments of the passion ( the events surrounding christ 's death ) : the column to which christ was tied during the flagellation , the sponge on a stick used to touch his lips with vinegar ( increasing his thirst ) , the nails and the lance that pierced his flesh . angels in front of the altar swing censors containing incense ( below ) . this is also a reference to the sacrament of the eucharist , where the bread and wine , offered by the priest during mass , become the body and blood of christ . the lamb bleeds from a wound in his side , and this stream of blood flows directly into a chalice set on the altar cloth ( the full inscription on the altar cloth reads , `` ecce agnus dei , qui tollis peccata mundi , miserere nobis , '' which translates , '' here is the lamb of god , who takes away the sins of the world '' ) . the flowing of the blood , visually linked to the spouts of water in the foreground fountain , is probably an allusion to christ as the “ living water ” of god . the fountain is therefore the fountain of life—a reference to the promise of eternal life made possible by christ 's sacrifice . this reference to christ as the “ living water ” occurs in the gospel of john . in that story , christ meets the woman of samaria at the well . when the woman questions christ ’ s presence there , “ jesus answered and said unto her , if thou knewest the gift of god , and who it is that saith to thee , give me to drink ; thou wouldest have asked of him , and he would have given thee living water. ” ( john 4:14 ) . inscribed on the fountain , in latin ( below ) , we see a verse from the book of revelation , '' then the angel showed me the river of the water of life , clear as crystal , proceeding from the throne of god and of the lamb . '' ( revelation , 22:1 ) . in the symbolic context of the lamb , the fountain is therefore the wellspring of eternal life and salvation . clustered around the fountain are yet more distinct processional groups worshipping the lamb . these are commonly identified as patriarchs and prophets from the old testament and male and female saints and church figures . if you 're wondering what the old testament figures are doing in paradise , in the byzantine tradition , christ ’ s death is followed by his harrowing of hell ( which takes place during the three days before his resurrection ) . in this episode ( while `` dead '' to the world ) , christ breaks open the doors of hell . he frees and saves pagan writers ( like homer ) , prophets of the old testament ( like moses ) , and adam and eve—all of whose deaths preceded christ's birth and who could not otherwise have experienced eternal salvation through his resurrection . together , these scenes , which relate to the gospel of john and the book of revelation , invite the viewer to share in the promise of salvation . these days , of course , we are invited to contemplate the altarpiece itself as a material survivor of time , war , reparation and restoration , and the painting has its own cult of dedicatees who worship it as an iconic work of art . the sum of its parts ( some thoughts on van eyck ’ s sources and influences ) the iconography of the ghent altarpiece may be read in a myriad of ways , and it would be impossible to do justice to all of them here . but there is one more message that is , i think , important . the central panels of the open position may be read downward vertically ; through the seated christ/god* figure , to the descent of the dove of the holy spirit , to the lamb on the altar . the symbolism of the trinity ( in christian theology , god , the holy spirit and christ are manifestations of one being ) is important because it was a doctrine that was frequently challenged in the western church . again , the gospel of john is often cited as most strongly defending and defining the divine nature of jesus , and supporting the trinitarian belief that the holy spirit shares the same being as jesus and god . in the thirteenth century , a philosopher named henry of ghent , from ghent of course , waded into the trinitarian question through his work on the metaphysics of being , and his work on the metaphysics of the trinity . it was not unusual for works of fifteenth-century art to engage with contemporary theological and philosophical debate . the iconography of the ghent altarpiece suggests that the artists ( or patron ) drew on very particular sources , perhaps even henry of ghent , although this is merely speculation . certainly , aspects of the iconography of the ghent altarpiece are peculiarly indebted to byzantine art , which we know jan van eyck had studied . his genius was in the commingling of the timelessly iconic with the naturalistic play of light across the temporal textures of the world , transforming the material into the miraculous . essay by dr. sally hickson *the central figure of the top register of the open altarpiece has been identified as both christ and god the father . some scholars has asserted that this ambiguity may have been purposeful . additional resources : getty foundation ghent altarpiece initiative a smarthistory video on a byzantine deësis mosaic from hagia sophia the ghent altarpiece from the web gallery of art the ghent altarpiece from the metropolitan museum of art 's heilbrunn timeline of art history
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in this episode ( while `` dead '' to the world ) , christ breaks open the doors of hell . he frees and saves pagan writers ( like homer ) , prophets of the old testament ( like moses ) , and adam and eve—all of whose deaths preceded christ's birth and who could not otherwise have experienced eternal salvation through his resurrection . together , these scenes , which relate to the gospel of john and the book of revelation , invite the viewer to share in the promise of salvation .
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- the corinthian column is the architecture scene is smooth black do we have something like this ?
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“ all art constantly aspires to the condition of music ” – walter pater a troubled past when he wrote that statement , i doubt that walter pater had in mind the veritable rock opera that is the ghent altarpiece , now housed in the cathedral of st. bavo , ghent ( in present-day belgium ) . from its singing , costumed , organ-pumping chorister angels to its gospel-choir legions of saints , soldiers , prophets and martyrs , to its central panel depicting the adoration of the mystic lamb—is there any other fifteenth-century altarpiece that even comes close in spirit to the 1970s theatrical excesses of rock operas like jesus christ superstar ? in the film the monuments men , george clooney solemnly pronounces the ghent altarpiece to be the most important work of art in the western tradition . as humbug as that may sound , it is certainly important , as much for its unparalleled technique as for what the painting has meant historically . removed from its place in the cathedral of ghent by napoleon ( well , the main panels , anyway ) and then by german occupying forces during world war i , the panels were returned and reassembled , only to be taken again by the nazis in 1942 and stored carelessly in a salt mine for the duration of the second world war . the altarpiece was rescued by allied art experts in 1945 ( below ) who reassembled , cleaned and restored the panels , which had lost much of their varnish and suffered some surface abrasion . since that time , the altarpiece has seldom failed to be in some process of constant condition monitoring ( as t.s . eliot would say “ like a patient etherized upon a table ” ) or some kind of reconstruction or conservation—a kind of cultural-historical exercise in trying to perfect the past . the latest campaign of study , restoration and renewal has gone on since 2009 , much of it carried out in front of the crowds at saint bavo 's cathedral and at the museum of fine arts in ghent . astonishingly , given its many trials and tribulations , the altarpiece has weathered well . only one of the original 12 panels ( 8 of which are part of the hinged shutter apparatus , and therefore painted on both sides ) , has been lost . in 1934 the panels depicting st. john the baptist , and another depicting the just judges were stolen from the church . the john the baptist panel was recovered . the just judges panel ( on the lower left when the altarpiece is open—see image at the top of the page ) was replaced with a modern copy during the 1945 restoration . the other panels have all survived , although there is some lingering disagreement about whether they are now reassembled in their original configuration , given the many times the altarpiece has been taken apart . a pixilated present the getty foundation in los angeles has funded the recent campaign to conserve the ghent altarpiece , an effort being led by belgium 's royal institute for cultural heritage . a painstaking photographic enlargement is captured in 100 million pixels on the `` closer to van eyck '' website . there , one can probe the impenetrably gorgeous enamel-like surface of van eyck ’ s greatest masterpiece , and gaze astonished at his virtuosic accomplishments . a moveable feast the altarpiece itself is a visual '' moveable feast , '' made up of 12 panels that fold against themselves ( see the video above ) . it is like frozen theatre , and when open , reveals a spiritual guidebook to divine revelation . in its basic configuration , the rather austere , largely monochromatic outer panels ( above ) —which show the kneeling patrons and statues of prophets and glimpses into orderly rooms ; are grounded in the material and sensible terrestrial world , in which gabriel appears to mary at the moment of the annunciation . but when the altarpiece is opened , we travel , accompanied by prophets on foot and princes on horseback , saints and martyrs and more angels , to the brilliantly-colored heart of the scene depicting the adoration of the mystic lamb ( below ) . it is as if the makers of the wizard of oz derived their inspiration for a black-and-white kansas and a technicolor oz , from ghent . byzantine influences the adoration of the mystic lamb ( above ) is presided over by the figure of god ( the bearded jesus with crown and scepter , below ) . * this figure can also be read as christ pantokrator ( one of the many names for god in the jewish tradition and , in the bible , an appellation used only by john the baptist to describe god ) , flanked by separate panels of john the baptist to the right and the virgin mary to the left ( below ) . the combination of these three figures reminds us of a byzantine image type—the deësis ( from the greek , “ prayer ” ) , which shows the intercession of the virgin mary and st. john the baptist for the salvation of our souls , the heavenly interview at the moment of the last judgement ( an example of a byzantine deësis , byzantine art refers to art from the byzantine or eastern roman empire ) . in the adoration of the mystic lamb ( left detail ) , the sacrifice of the lamb , symbol of christ ’ s slaughter for our salvation , is similarly byzantine in origin . the inner panels are painted in the bold and dynamic naturalistic style for which the artist jan van eyck is justifiably famous . in all of its positions , the ghent altarpiece is a vision of the visionary . it alludes not only to sight but to sound—musical angels accompanying the elaborate orchestration of the whole . its appeal to the senses threatens to overwhelm the intellectual apprehension of its content . the artists according to an inscription , written on two silver strips mounted on the rear of the two donor panels , and only discovered in 1823 , the altarpiece was painted by the brothers jan and hubert van eyck : the painter hubert van eyck , than whom none was greater , began this work . jan [ his brother ] , second in art , completed it at the request of joos [ jodocus ] vijd on the sixth of may [ 1432 ] . he begs you by means of this verse to take care of what came into being . because jan van eyck is seen as the far more famous of the two brothers , the reference to jan as `` second in art '' has raised a few eyebrows among art historians , eager to assign the lion ’ s share of the work to young jan. my own undergraduate professor postulated that what the inscription means is that hubert was responsible for the actual construction of the altarpiece , which was later largely painted by jan—a not unusual sequence of events in a fifteenth-century workshop ( building polyptych , or many-paneled , altarpieces required construction knowledge , and painting them required an entirely different expertise ) . hubert died in 1426 , and the altarpiece was finished in 1432 , so jan probably took over the contract hubert signed with the patron of the work , judocos vijd ( sometimes spelled `` vijdt '' ) , which also would have made jan literally `` second in art . '' we know jan to have been an exquisite painter of miniatures who worked for the dukes of burgundy , and there are many aspects of the work here consistent with the detailed work of a manuscript illuminator , but there are also some important differences , particularly in scale . the relatively large size of the panels pushed jan to new heights of virtuosity as a master of light ; directional light , saturation , the softest scale of illuminations in the gradation of shadow , the construction of space through light and shade , symphonies of reflection and refraction alive in a world of textured surfaces—literally , the light of the world . here , for the first time on such a scale , is a picture of the completely natural world saturated by the light of god—the perfect intermingling of divine illumination with the created world—and all described in paint . van eyck creates a world within the painting as substantial and real as the world outside the painting . say what you will about brunelleschi and masaccio and linear perspective in florence , without the subtlety of oil paint , their works look like mathematical equations beside the painted world of the ghent altarpiece . the patrons like most renaissance patrons , jodocus vijd was a wealthy merchant who sought to expiate the sin of being too fond of money by spending some of it on creating a monument to god . an influential citizen of ghent , vijd commissioned the altarpiece for the church dedicated to st. john the baptist ( now the cathedral of st. bavo ) in his home city as a means of saving his soul while simultaneously celebrating his wealth . vijd was warden of the church of st. john and assistant burgomeister of ghent , and he had a rich aristocratic wife , so he had plenty of money to commission the van eyck brothers . it is uncertain the extent to which he influenced the iconography of the overall work , but he obviously spared no expense . the distinctive faces of jodocus vijd and elizabeth borluut ( the husband and wife patrons ) are each shown in three-quarter view ( left and below ) . they kneel in the traditional donor positions , with their hands clasped in prayer , facing each other and gazing vaguely toward the central panels . undoubtedly , contemporaries would have recognized them taking pride of place in such an important civic church , and although the immediacy of their presence would fade with time , their identities as the donors of the work remain intact . the altarpiece , closed it is best to start in the smallest and most constricted stage of the altarpiece in its closed position . the kneeling donors are depicted on the outer extremes , separated by simulated statues of two standing saints painted in grisaille ( shades of grey ) —st . john the baptist and st. john the evangelist ( above ) . in the register above is a depiction of the annunciation—this is the moment when the archangel gabriel announces to mary that she will be the mother of christ ( above ) . figures of the angel and mary are found on the outer edges of the panels . the holy spirit hovers over mary . the two contiguous scenes between them are pure genre scenes ( scenes of everyday life ) . beside gabriel , a window opens onto a view of buildings in ghent ( left ) , beside the virgin , a recessed niche holds a silver tray , a small hanging silver pitcher and a linen towel neatly hanging from a rack ( below ) . these items are consistent with iconography of the period that uses domestic objects as a means of expressing the purity of the virgin . we are drawn most deeply into the center of the altarpiece ( achieved without mathematically calculated perspective—you can tell because the floor appears to tilt upward ) , toward the mystery within . at the top of the gabriel panel , beneath a shallow rounded arch , is the old testament prophet zacharias , father of john the baptist ; and above the virgin , we see the old testament prophet micah , who predicted the birth of the messiah in bethlehem . the two central panels in this upper register depict the erythraean and cumaean sibyls ( sibyls are female figures from ancient greece and rome who prophesied the future ) . these four figures are all messengers of the incarnation and sacrifice of christ ( michelangelo painted these prophets and sibyls in the sistine chapel , and more ) . the altarpiece , open opened , the altarpiece is divided into two horizontal registers . the deësis ( the virgin mary , christ/god , * and st. john the baptist ) panels are flanked on either side by choirs of heavenly angels and , on the outermost panels at each side , adam and eve . god ’ s first human creatures are therefore the parenthetical figures of this upper register and the figures that necessitate the salvation scene below ) . their literal marginalization—at the edges of the altarpiece—is indicative of their state of sin . eve holds the forbidden fruit and covers her genitals . opposite her , adam assumes the classical pose of the so-called `` modest venus , '' one arm across his chest , the other covering his genitals ( a rather peculiar pose for a male figure to assume ) . adam and eve 's sin in the garden of eden ( the fall of man ) is , of course , the reason for all that occurs below in the panel known as the adoration of the mystic lamb—the full salvation play , complete with sacrificial lamb , a symbolic representation of christ ( from gospel of john : '' the next day john saw jesus coming toward him , and said , 'behold ! the lamb of god who takes away the sin of the world ! ' '' —john 1:29 ) . from the outer edges of the lower panels , crowds converge towards the altar in the center , presenting a unified field across the five panels , overcoming the gothic division of the frame . from the left come figures known as the just judges and the soldiers of christ , on horseback , arrayed in glittering armor and armed with swords of justice , followed by the judges wearing opulent and various finery . from the right come the saints and the prophets , chief among them the giant ( and apocryphal ) st. christopher ( below ) , the male saints suitably dressed in simple tunics and robes in sober earth tones . these crowds approach the central panel . where are they all going ? they ’ re going to witness the sacrifice of the mystic lamb . the adoration of the mystic lamb the key panel of the altarpiece , the adoration of the mystic lamb ( detail above ) , depicts a large meadow , dotted with flowers , at the centre of which are two key structures—in the foreground is a lovely octagonal stone fountain , with a tall central pedestal from which spring multiple cascades of water . in the background , on a direct axis with the fountain , is an altar with a lamb standing on it . the head of the strangely alert lamb is surrounded by a glowing nimbus ( a halo , here depicted as golden rays ) . in the sky above , the dove of the holy spirit descends in its own pulsating nimbus of light from which radiate long , golden spires that touch the angels and the ground . behind the altar , in the distance , are trees and one tall tower , punctuated by windows ( left ) . still further back on the blue horizon are distant mountains ; the setting is a paradisiacal landscape for the re-enactment of the sacrifice of christ . what is the relationship between the altar , the sacrifice of the lamb , and the foreground fountain ? the mystic lamb is the lamb of god—the sacrificial lamb—a symbol of christ and christ ’ s death . the lamb on the altar is equivalent to the crucifixion of christ , made explicit by the juxtaposition of the lamb with the cross held by the angel . other angels behind the altar hold the instruments of the passion ( the events surrounding christ 's death ) : the column to which christ was tied during the flagellation , the sponge on a stick used to touch his lips with vinegar ( increasing his thirst ) , the nails and the lance that pierced his flesh . angels in front of the altar swing censors containing incense ( below ) . this is also a reference to the sacrament of the eucharist , where the bread and wine , offered by the priest during mass , become the body and blood of christ . the lamb bleeds from a wound in his side , and this stream of blood flows directly into a chalice set on the altar cloth ( the full inscription on the altar cloth reads , `` ecce agnus dei , qui tollis peccata mundi , miserere nobis , '' which translates , '' here is the lamb of god , who takes away the sins of the world '' ) . the flowing of the blood , visually linked to the spouts of water in the foreground fountain , is probably an allusion to christ as the “ living water ” of god . the fountain is therefore the fountain of life—a reference to the promise of eternal life made possible by christ 's sacrifice . this reference to christ as the “ living water ” occurs in the gospel of john . in that story , christ meets the woman of samaria at the well . when the woman questions christ ’ s presence there , “ jesus answered and said unto her , if thou knewest the gift of god , and who it is that saith to thee , give me to drink ; thou wouldest have asked of him , and he would have given thee living water. ” ( john 4:14 ) . inscribed on the fountain , in latin ( below ) , we see a verse from the book of revelation , '' then the angel showed me the river of the water of life , clear as crystal , proceeding from the throne of god and of the lamb . '' ( revelation , 22:1 ) . in the symbolic context of the lamb , the fountain is therefore the wellspring of eternal life and salvation . clustered around the fountain are yet more distinct processional groups worshipping the lamb . these are commonly identified as patriarchs and prophets from the old testament and male and female saints and church figures . if you 're wondering what the old testament figures are doing in paradise , in the byzantine tradition , christ ’ s death is followed by his harrowing of hell ( which takes place during the three days before his resurrection ) . in this episode ( while `` dead '' to the world ) , christ breaks open the doors of hell . he frees and saves pagan writers ( like homer ) , prophets of the old testament ( like moses ) , and adam and eve—all of whose deaths preceded christ's birth and who could not otherwise have experienced eternal salvation through his resurrection . together , these scenes , which relate to the gospel of john and the book of revelation , invite the viewer to share in the promise of salvation . these days , of course , we are invited to contemplate the altarpiece itself as a material survivor of time , war , reparation and restoration , and the painting has its own cult of dedicatees who worship it as an iconic work of art . the sum of its parts ( some thoughts on van eyck ’ s sources and influences ) the iconography of the ghent altarpiece may be read in a myriad of ways , and it would be impossible to do justice to all of them here . but there is one more message that is , i think , important . the central panels of the open position may be read downward vertically ; through the seated christ/god* figure , to the descent of the dove of the holy spirit , to the lamb on the altar . the symbolism of the trinity ( in christian theology , god , the holy spirit and christ are manifestations of one being ) is important because it was a doctrine that was frequently challenged in the western church . again , the gospel of john is often cited as most strongly defending and defining the divine nature of jesus , and supporting the trinitarian belief that the holy spirit shares the same being as jesus and god . in the thirteenth century , a philosopher named henry of ghent , from ghent of course , waded into the trinitarian question through his work on the metaphysics of being , and his work on the metaphysics of the trinity . it was not unusual for works of fifteenth-century art to engage with contemporary theological and philosophical debate . the iconography of the ghent altarpiece suggests that the artists ( or patron ) drew on very particular sources , perhaps even henry of ghent , although this is merely speculation . certainly , aspects of the iconography of the ghent altarpiece are peculiarly indebted to byzantine art , which we know jan van eyck had studied . his genius was in the commingling of the timelessly iconic with the naturalistic play of light across the temporal textures of the world , transforming the material into the miraculous . essay by dr. sally hickson *the central figure of the top register of the open altarpiece has been identified as both christ and god the father . some scholars has asserted that this ambiguity may have been purposeful . additional resources : getty foundation ghent altarpiece initiative a smarthistory video on a byzantine deësis mosaic from hagia sophia the ghent altarpiece from the web gallery of art the ghent altarpiece from the metropolitan museum of art 's heilbrunn timeline of art history
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in its basic configuration , the rather austere , largely monochromatic outer panels ( above ) —which show the kneeling patrons and statues of prophets and glimpses into orderly rooms ; are grounded in the material and sensible terrestrial world , in which gabriel appears to mary at the moment of the annunciation . but when the altarpiece is opened , we travel , accompanied by prophets on foot and princes on horseback , saints and martyrs and more angels , to the brilliantly-colored heart of the scene depicting the adoration of the mystic lamb ( below ) . it is as if the makers of the wizard of oz derived their inspiration for a black-and-white kansas and a technicolor oz , from ghent .
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- on the singing angels scene there is a depicting of a soldier battling with snakes who is he and what does it present ?
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“ all art constantly aspires to the condition of music ” – walter pater a troubled past when he wrote that statement , i doubt that walter pater had in mind the veritable rock opera that is the ghent altarpiece , now housed in the cathedral of st. bavo , ghent ( in present-day belgium ) . from its singing , costumed , organ-pumping chorister angels to its gospel-choir legions of saints , soldiers , prophets and martyrs , to its central panel depicting the adoration of the mystic lamb—is there any other fifteenth-century altarpiece that even comes close in spirit to the 1970s theatrical excesses of rock operas like jesus christ superstar ? in the film the monuments men , george clooney solemnly pronounces the ghent altarpiece to be the most important work of art in the western tradition . as humbug as that may sound , it is certainly important , as much for its unparalleled technique as for what the painting has meant historically . removed from its place in the cathedral of ghent by napoleon ( well , the main panels , anyway ) and then by german occupying forces during world war i , the panels were returned and reassembled , only to be taken again by the nazis in 1942 and stored carelessly in a salt mine for the duration of the second world war . the altarpiece was rescued by allied art experts in 1945 ( below ) who reassembled , cleaned and restored the panels , which had lost much of their varnish and suffered some surface abrasion . since that time , the altarpiece has seldom failed to be in some process of constant condition monitoring ( as t.s . eliot would say “ like a patient etherized upon a table ” ) or some kind of reconstruction or conservation—a kind of cultural-historical exercise in trying to perfect the past . the latest campaign of study , restoration and renewal has gone on since 2009 , much of it carried out in front of the crowds at saint bavo 's cathedral and at the museum of fine arts in ghent . astonishingly , given its many trials and tribulations , the altarpiece has weathered well . only one of the original 12 panels ( 8 of which are part of the hinged shutter apparatus , and therefore painted on both sides ) , has been lost . in 1934 the panels depicting st. john the baptist , and another depicting the just judges were stolen from the church . the john the baptist panel was recovered . the just judges panel ( on the lower left when the altarpiece is open—see image at the top of the page ) was replaced with a modern copy during the 1945 restoration . the other panels have all survived , although there is some lingering disagreement about whether they are now reassembled in their original configuration , given the many times the altarpiece has been taken apart . a pixilated present the getty foundation in los angeles has funded the recent campaign to conserve the ghent altarpiece , an effort being led by belgium 's royal institute for cultural heritage . a painstaking photographic enlargement is captured in 100 million pixels on the `` closer to van eyck '' website . there , one can probe the impenetrably gorgeous enamel-like surface of van eyck ’ s greatest masterpiece , and gaze astonished at his virtuosic accomplishments . a moveable feast the altarpiece itself is a visual '' moveable feast , '' made up of 12 panels that fold against themselves ( see the video above ) . it is like frozen theatre , and when open , reveals a spiritual guidebook to divine revelation . in its basic configuration , the rather austere , largely monochromatic outer panels ( above ) —which show the kneeling patrons and statues of prophets and glimpses into orderly rooms ; are grounded in the material and sensible terrestrial world , in which gabriel appears to mary at the moment of the annunciation . but when the altarpiece is opened , we travel , accompanied by prophets on foot and princes on horseback , saints and martyrs and more angels , to the brilliantly-colored heart of the scene depicting the adoration of the mystic lamb ( below ) . it is as if the makers of the wizard of oz derived their inspiration for a black-and-white kansas and a technicolor oz , from ghent . byzantine influences the adoration of the mystic lamb ( above ) is presided over by the figure of god ( the bearded jesus with crown and scepter , below ) . * this figure can also be read as christ pantokrator ( one of the many names for god in the jewish tradition and , in the bible , an appellation used only by john the baptist to describe god ) , flanked by separate panels of john the baptist to the right and the virgin mary to the left ( below ) . the combination of these three figures reminds us of a byzantine image type—the deësis ( from the greek , “ prayer ” ) , which shows the intercession of the virgin mary and st. john the baptist for the salvation of our souls , the heavenly interview at the moment of the last judgement ( an example of a byzantine deësis , byzantine art refers to art from the byzantine or eastern roman empire ) . in the adoration of the mystic lamb ( left detail ) , the sacrifice of the lamb , symbol of christ ’ s slaughter for our salvation , is similarly byzantine in origin . the inner panels are painted in the bold and dynamic naturalistic style for which the artist jan van eyck is justifiably famous . in all of its positions , the ghent altarpiece is a vision of the visionary . it alludes not only to sight but to sound—musical angels accompanying the elaborate orchestration of the whole . its appeal to the senses threatens to overwhelm the intellectual apprehension of its content . the artists according to an inscription , written on two silver strips mounted on the rear of the two donor panels , and only discovered in 1823 , the altarpiece was painted by the brothers jan and hubert van eyck : the painter hubert van eyck , than whom none was greater , began this work . jan [ his brother ] , second in art , completed it at the request of joos [ jodocus ] vijd on the sixth of may [ 1432 ] . he begs you by means of this verse to take care of what came into being . because jan van eyck is seen as the far more famous of the two brothers , the reference to jan as `` second in art '' has raised a few eyebrows among art historians , eager to assign the lion ’ s share of the work to young jan. my own undergraduate professor postulated that what the inscription means is that hubert was responsible for the actual construction of the altarpiece , which was later largely painted by jan—a not unusual sequence of events in a fifteenth-century workshop ( building polyptych , or many-paneled , altarpieces required construction knowledge , and painting them required an entirely different expertise ) . hubert died in 1426 , and the altarpiece was finished in 1432 , so jan probably took over the contract hubert signed with the patron of the work , judocos vijd ( sometimes spelled `` vijdt '' ) , which also would have made jan literally `` second in art . '' we know jan to have been an exquisite painter of miniatures who worked for the dukes of burgundy , and there are many aspects of the work here consistent with the detailed work of a manuscript illuminator , but there are also some important differences , particularly in scale . the relatively large size of the panels pushed jan to new heights of virtuosity as a master of light ; directional light , saturation , the softest scale of illuminations in the gradation of shadow , the construction of space through light and shade , symphonies of reflection and refraction alive in a world of textured surfaces—literally , the light of the world . here , for the first time on such a scale , is a picture of the completely natural world saturated by the light of god—the perfect intermingling of divine illumination with the created world—and all described in paint . van eyck creates a world within the painting as substantial and real as the world outside the painting . say what you will about brunelleschi and masaccio and linear perspective in florence , without the subtlety of oil paint , their works look like mathematical equations beside the painted world of the ghent altarpiece . the patrons like most renaissance patrons , jodocus vijd was a wealthy merchant who sought to expiate the sin of being too fond of money by spending some of it on creating a monument to god . an influential citizen of ghent , vijd commissioned the altarpiece for the church dedicated to st. john the baptist ( now the cathedral of st. bavo ) in his home city as a means of saving his soul while simultaneously celebrating his wealth . vijd was warden of the church of st. john and assistant burgomeister of ghent , and he had a rich aristocratic wife , so he had plenty of money to commission the van eyck brothers . it is uncertain the extent to which he influenced the iconography of the overall work , but he obviously spared no expense . the distinctive faces of jodocus vijd and elizabeth borluut ( the husband and wife patrons ) are each shown in three-quarter view ( left and below ) . they kneel in the traditional donor positions , with their hands clasped in prayer , facing each other and gazing vaguely toward the central panels . undoubtedly , contemporaries would have recognized them taking pride of place in such an important civic church , and although the immediacy of their presence would fade with time , their identities as the donors of the work remain intact . the altarpiece , closed it is best to start in the smallest and most constricted stage of the altarpiece in its closed position . the kneeling donors are depicted on the outer extremes , separated by simulated statues of two standing saints painted in grisaille ( shades of grey ) —st . john the baptist and st. john the evangelist ( above ) . in the register above is a depiction of the annunciation—this is the moment when the archangel gabriel announces to mary that she will be the mother of christ ( above ) . figures of the angel and mary are found on the outer edges of the panels . the holy spirit hovers over mary . the two contiguous scenes between them are pure genre scenes ( scenes of everyday life ) . beside gabriel , a window opens onto a view of buildings in ghent ( left ) , beside the virgin , a recessed niche holds a silver tray , a small hanging silver pitcher and a linen towel neatly hanging from a rack ( below ) . these items are consistent with iconography of the period that uses domestic objects as a means of expressing the purity of the virgin . we are drawn most deeply into the center of the altarpiece ( achieved without mathematically calculated perspective—you can tell because the floor appears to tilt upward ) , toward the mystery within . at the top of the gabriel panel , beneath a shallow rounded arch , is the old testament prophet zacharias , father of john the baptist ; and above the virgin , we see the old testament prophet micah , who predicted the birth of the messiah in bethlehem . the two central panels in this upper register depict the erythraean and cumaean sibyls ( sibyls are female figures from ancient greece and rome who prophesied the future ) . these four figures are all messengers of the incarnation and sacrifice of christ ( michelangelo painted these prophets and sibyls in the sistine chapel , and more ) . the altarpiece , open opened , the altarpiece is divided into two horizontal registers . the deësis ( the virgin mary , christ/god , * and st. john the baptist ) panels are flanked on either side by choirs of heavenly angels and , on the outermost panels at each side , adam and eve . god ’ s first human creatures are therefore the parenthetical figures of this upper register and the figures that necessitate the salvation scene below ) . their literal marginalization—at the edges of the altarpiece—is indicative of their state of sin . eve holds the forbidden fruit and covers her genitals . opposite her , adam assumes the classical pose of the so-called `` modest venus , '' one arm across his chest , the other covering his genitals ( a rather peculiar pose for a male figure to assume ) . adam and eve 's sin in the garden of eden ( the fall of man ) is , of course , the reason for all that occurs below in the panel known as the adoration of the mystic lamb—the full salvation play , complete with sacrificial lamb , a symbolic representation of christ ( from gospel of john : '' the next day john saw jesus coming toward him , and said , 'behold ! the lamb of god who takes away the sin of the world ! ' '' —john 1:29 ) . from the outer edges of the lower panels , crowds converge towards the altar in the center , presenting a unified field across the five panels , overcoming the gothic division of the frame . from the left come figures known as the just judges and the soldiers of christ , on horseback , arrayed in glittering armor and armed with swords of justice , followed by the judges wearing opulent and various finery . from the right come the saints and the prophets , chief among them the giant ( and apocryphal ) st. christopher ( below ) , the male saints suitably dressed in simple tunics and robes in sober earth tones . these crowds approach the central panel . where are they all going ? they ’ re going to witness the sacrifice of the mystic lamb . the adoration of the mystic lamb the key panel of the altarpiece , the adoration of the mystic lamb ( detail above ) , depicts a large meadow , dotted with flowers , at the centre of which are two key structures—in the foreground is a lovely octagonal stone fountain , with a tall central pedestal from which spring multiple cascades of water . in the background , on a direct axis with the fountain , is an altar with a lamb standing on it . the head of the strangely alert lamb is surrounded by a glowing nimbus ( a halo , here depicted as golden rays ) . in the sky above , the dove of the holy spirit descends in its own pulsating nimbus of light from which radiate long , golden spires that touch the angels and the ground . behind the altar , in the distance , are trees and one tall tower , punctuated by windows ( left ) . still further back on the blue horizon are distant mountains ; the setting is a paradisiacal landscape for the re-enactment of the sacrifice of christ . what is the relationship between the altar , the sacrifice of the lamb , and the foreground fountain ? the mystic lamb is the lamb of god—the sacrificial lamb—a symbol of christ and christ ’ s death . the lamb on the altar is equivalent to the crucifixion of christ , made explicit by the juxtaposition of the lamb with the cross held by the angel . other angels behind the altar hold the instruments of the passion ( the events surrounding christ 's death ) : the column to which christ was tied during the flagellation , the sponge on a stick used to touch his lips with vinegar ( increasing his thirst ) , the nails and the lance that pierced his flesh . angels in front of the altar swing censors containing incense ( below ) . this is also a reference to the sacrament of the eucharist , where the bread and wine , offered by the priest during mass , become the body and blood of christ . the lamb bleeds from a wound in his side , and this stream of blood flows directly into a chalice set on the altar cloth ( the full inscription on the altar cloth reads , `` ecce agnus dei , qui tollis peccata mundi , miserere nobis , '' which translates , '' here is the lamb of god , who takes away the sins of the world '' ) . the flowing of the blood , visually linked to the spouts of water in the foreground fountain , is probably an allusion to christ as the “ living water ” of god . the fountain is therefore the fountain of life—a reference to the promise of eternal life made possible by christ 's sacrifice . this reference to christ as the “ living water ” occurs in the gospel of john . in that story , christ meets the woman of samaria at the well . when the woman questions christ ’ s presence there , “ jesus answered and said unto her , if thou knewest the gift of god , and who it is that saith to thee , give me to drink ; thou wouldest have asked of him , and he would have given thee living water. ” ( john 4:14 ) . inscribed on the fountain , in latin ( below ) , we see a verse from the book of revelation , '' then the angel showed me the river of the water of life , clear as crystal , proceeding from the throne of god and of the lamb . '' ( revelation , 22:1 ) . in the symbolic context of the lamb , the fountain is therefore the wellspring of eternal life and salvation . clustered around the fountain are yet more distinct processional groups worshipping the lamb . these are commonly identified as patriarchs and prophets from the old testament and male and female saints and church figures . if you 're wondering what the old testament figures are doing in paradise , in the byzantine tradition , christ ’ s death is followed by his harrowing of hell ( which takes place during the three days before his resurrection ) . in this episode ( while `` dead '' to the world ) , christ breaks open the doors of hell . he frees and saves pagan writers ( like homer ) , prophets of the old testament ( like moses ) , and adam and eve—all of whose deaths preceded christ's birth and who could not otherwise have experienced eternal salvation through his resurrection . together , these scenes , which relate to the gospel of john and the book of revelation , invite the viewer to share in the promise of salvation . these days , of course , we are invited to contemplate the altarpiece itself as a material survivor of time , war , reparation and restoration , and the painting has its own cult of dedicatees who worship it as an iconic work of art . the sum of its parts ( some thoughts on van eyck ’ s sources and influences ) the iconography of the ghent altarpiece may be read in a myriad of ways , and it would be impossible to do justice to all of them here . but there is one more message that is , i think , important . the central panels of the open position may be read downward vertically ; through the seated christ/god* figure , to the descent of the dove of the holy spirit , to the lamb on the altar . the symbolism of the trinity ( in christian theology , god , the holy spirit and christ are manifestations of one being ) is important because it was a doctrine that was frequently challenged in the western church . again , the gospel of john is often cited as most strongly defending and defining the divine nature of jesus , and supporting the trinitarian belief that the holy spirit shares the same being as jesus and god . in the thirteenth century , a philosopher named henry of ghent , from ghent of course , waded into the trinitarian question through his work on the metaphysics of being , and his work on the metaphysics of the trinity . it was not unusual for works of fifteenth-century art to engage with contemporary theological and philosophical debate . the iconography of the ghent altarpiece suggests that the artists ( or patron ) drew on very particular sources , perhaps even henry of ghent , although this is merely speculation . certainly , aspects of the iconography of the ghent altarpiece are peculiarly indebted to byzantine art , which we know jan van eyck had studied . his genius was in the commingling of the timelessly iconic with the naturalistic play of light across the temporal textures of the world , transforming the material into the miraculous . essay by dr. sally hickson *the central figure of the top register of the open altarpiece has been identified as both christ and god the father . some scholars has asserted that this ambiguity may have been purposeful . additional resources : getty foundation ghent altarpiece initiative a smarthistory video on a byzantine deësis mosaic from hagia sophia the ghent altarpiece from the web gallery of art the ghent altarpiece from the metropolitan museum of art 's heilbrunn timeline of art history
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from the right come the saints and the prophets , chief among them the giant ( and apocryphal ) st. christopher ( below ) , the male saints suitably dressed in simple tunics and robes in sober earth tones . these crowds approach the central panel . where are they all going ?
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does the attire of the pilgrims or people in the center panel identify them as being associated with a particular monastic order or confraternity ?
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key points : gregor mendel studied inheritance of traits in pea plants . he proposed a model where pairs of `` heritable elements , '' or genes , specified traits . genes come in different versions , or alleles . a dominant allele hides a recessive allele and determines the organism 's appearance . when an organism makes gametes , each gamete receives just one gene copy , which is selected randomly . this is known as the law of segregation . a punnett square can be used to predict genotypes ( allele combinations ) and phenotypes ( observable traits ) of offspring from genetic crosses . a test cross can be used to determine whether an organism with a dominant phenotype is homozygous or heterozygous . introduction today , we know that many of people 's characteristics , from hair color to height to risk of diabetes , are influenced by genes . we also know that genes are the way parents pass characteristics on to their children ( including things like dimples , or—in the case of me and my father—a terrible singing voice ) . in the last hundred years , we 've come to understand that genes are actually pieces of dna that are found on chromosomes and specify proteins . but did we always know those things ? not by a long shot ! about $ 150 $ years ago , a monk named gregor mendel published a paper that first proposed the existence of genes and presented a model for how they were inherited . mendel 's work was the first step on a long road , involving many hard-working scientists , that 's led to our present understanding of genes and what they do . in this article , we ’ ll trace the experiments and reasoning that led mendel to formulate his model for the inheritance of single genes . mendel 's model : it started with a $ 3:1 $ ratio mendel studied the genetics of pea plants , and he traced the inheritance of a variety of characteristics , including flower color , flower position , seed color , and seed shape . to do so , he started by crossing pure-breeding parent plants with different forms of a characteristic , such as violet and white flowers . pure-breeding just means that the plant will always make more offspring like itself , when self-fertilized over many generations . what results did mendel find in his crosses for flower color ? in the parental , or $ \text p $ generation , mendel crossed a pure-breeding violet-flowered plant to a pure-breeding white-flowered plant . when he gathered and planted the seeds produced in this cross , mendel found that $ 100 $ percent of the plants in the next generation , or $ \text f_1 $ generation , had violet flowers . conventional wisdom at that time would have predicted that the hybrid flowers should be pale violet—that is , that the parents ' traits should blend in the offspring . instead , mendel ’ s results showed that the white flower trait had completely disappeared . he called the trait that was visible in the $ \text f_1 $ generation ( violet flowers ) the dominant trait , and the trait that was hidden or lost ( white flowers ) the recessive trait . importantly , mendel did not stop his experimentation there . instead , he let the $ \text f_1 $ plants self-fertilize . among their offspring , called the $ \text f_2 $ generation , he found that $ 705 $ plants had violet flowers and $ 224 $ had white flowers . this was a ratio of $ 3.15 $ violet flowers to one white flower , or approximately $ 3:1 $ . this $ 3:1 $ ratio was no fluke . for the other six characteristics that mendel examined , both the $ \text f_1 $ and $ \text f_2 $ generations behaved in the same way they did for flower color . one of the two traits would disappear completely from the $ \text f_1 $ generation , only to reappear in the $ \text f_2 $ generation in a ratio of roughly $ 3:1 $ as it turned out , the $ 3:1 $ ratio was a crucial clue that let mendel crack the puzzle of inheritance . let 's take a closer look at what mendel figured out . mendel 's model of inheritance based on his results ( including that magic $ 3:1 $ ratio ) , mendel came up with a model for the inheritance of individual characteristics , such as flower color . in mendel 's model , parents pass along “ heritable factors , '' which we now call genes , that determine the traits of the offspring . each individual has two copies of a given gene , such as the gene for seed color ( y gene ) shown below . if these copies represent different versions , or alleles , of the gene , one allele—the dominant one—may hide the other allele—the recessive one . for seed color , the dominant yellow allele y hides the recessive green allele y . the set of alleles carried by an organism is known as its genotype . genotype determines phenotype , an organism 's observable features . when an organism has two copies of the same allele ( say , yy or yy ) , it is said to be homozygous for that gene . if , instead , it has two different copies ( like yy ) , we can say it is heterozygous . phenotype can also be affected by the environment in many real-life cases , though this did not have an impact on mendel 's work . mendel 's model : the law of segregation so far , so good . but this model alone does n't explain why mendel saw the exact patterns of inheritance he did . in particular , it does n't account for the $ 3:1 $ ratio . for that , we need mendel 's law of segregation . according to the law of segregation , only one of the two gene copies present in an organism is distributed to each gamete ( egg or sperm cell ) that it makes , and the allocation of the gene copies is random . when an egg and a sperm join in fertilization , they form a new organism , whose genotype consists of the alleles contained in the gametes . the diagram below illustrates this idea : the four-squared box shown for the $ \text f_2 $ generation is known as a punnett square . to prepare a punnett square , all possible gametes made by the parents are written along the top ( for the father ) and side ( for the mother ) of a grid . here , since it is self-fertilization , the same plant is both mother and father . the combinations of egg and sperm are then made in the boxes in the table , representing fertilization to make new individuals . because each square represents an equally likely event , we can determine genotype and phenotype ratios by counting the squares . the test cross mendel also came up with a way to figure out whether an organism with a dominant phenotype ( such as a yellow-seeded pea plant ) was a heterozygote ( yy ) or a homozygote ( yy ) . this technique is called a test cross and is still used by plant and animal breeders today . in a test cross , the organism with the dominant phenotype is crossed with an organism that is homozygous recessive ( e.g. , green-seeded ) : if the organism with the dominant phenotype is homozygous , then all of the $ \text f_1 $ offspring will get a dominant allele from that parent , be heterozygous , and show the dominant phenotype . if the organism with the dominant phenotype organism is instead a heterozygote , the $ \text f_1 $ offspring will be half heterozygotes ( dominant phenotype ) and half recessive homozygotes ( recessive phenotype ) . the fact that we get a $ 1:1 $ ratio in this second case is another confirmation of mendel ’ s law of segregation . is that mendel 's complete model of inheritance ? not quite ! we 've seen all of mendel 's model for the inheritance of single genes . however , mendel 's complete model also addressed whether genes for different characteristics ( such as flower color and seed shape ) influence each other 's inheritance . you can learn more about mendel 's model for the inheritance of multiple genes in the law of independent assortment article . one thing i find pretty amazing is that mendel was able to figure out his entire model of inheritance simply from his observations of pea plants . this was n't because he was some kind of crazy super genius , but rather , because he was very careful , persistent , and curious , and also because he thought about his results mathematically ( for instance , the $ 3:1 $ ratio ) . these are some of the qualities of a great scientist—ones that anyone , anywhere , can develop !
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he proposed a model where pairs of `` heritable elements , '' or genes , specified traits . genes come in different versions , or alleles . a dominant allele hides a recessive allele and determines the organism 's appearance .
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homologous genes come from homologous chromosomes ?
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key points : gregor mendel studied inheritance of traits in pea plants . he proposed a model where pairs of `` heritable elements , '' or genes , specified traits . genes come in different versions , or alleles . a dominant allele hides a recessive allele and determines the organism 's appearance . when an organism makes gametes , each gamete receives just one gene copy , which is selected randomly . this is known as the law of segregation . a punnett square can be used to predict genotypes ( allele combinations ) and phenotypes ( observable traits ) of offspring from genetic crosses . a test cross can be used to determine whether an organism with a dominant phenotype is homozygous or heterozygous . introduction today , we know that many of people 's characteristics , from hair color to height to risk of diabetes , are influenced by genes . we also know that genes are the way parents pass characteristics on to their children ( including things like dimples , or—in the case of me and my father—a terrible singing voice ) . in the last hundred years , we 've come to understand that genes are actually pieces of dna that are found on chromosomes and specify proteins . but did we always know those things ? not by a long shot ! about $ 150 $ years ago , a monk named gregor mendel published a paper that first proposed the existence of genes and presented a model for how they were inherited . mendel 's work was the first step on a long road , involving many hard-working scientists , that 's led to our present understanding of genes and what they do . in this article , we ’ ll trace the experiments and reasoning that led mendel to formulate his model for the inheritance of single genes . mendel 's model : it started with a $ 3:1 $ ratio mendel studied the genetics of pea plants , and he traced the inheritance of a variety of characteristics , including flower color , flower position , seed color , and seed shape . to do so , he started by crossing pure-breeding parent plants with different forms of a characteristic , such as violet and white flowers . pure-breeding just means that the plant will always make more offspring like itself , when self-fertilized over many generations . what results did mendel find in his crosses for flower color ? in the parental , or $ \text p $ generation , mendel crossed a pure-breeding violet-flowered plant to a pure-breeding white-flowered plant . when he gathered and planted the seeds produced in this cross , mendel found that $ 100 $ percent of the plants in the next generation , or $ \text f_1 $ generation , had violet flowers . conventional wisdom at that time would have predicted that the hybrid flowers should be pale violet—that is , that the parents ' traits should blend in the offspring . instead , mendel ’ s results showed that the white flower trait had completely disappeared . he called the trait that was visible in the $ \text f_1 $ generation ( violet flowers ) the dominant trait , and the trait that was hidden or lost ( white flowers ) the recessive trait . importantly , mendel did not stop his experimentation there . instead , he let the $ \text f_1 $ plants self-fertilize . among their offspring , called the $ \text f_2 $ generation , he found that $ 705 $ plants had violet flowers and $ 224 $ had white flowers . this was a ratio of $ 3.15 $ violet flowers to one white flower , or approximately $ 3:1 $ . this $ 3:1 $ ratio was no fluke . for the other six characteristics that mendel examined , both the $ \text f_1 $ and $ \text f_2 $ generations behaved in the same way they did for flower color . one of the two traits would disappear completely from the $ \text f_1 $ generation , only to reappear in the $ \text f_2 $ generation in a ratio of roughly $ 3:1 $ as it turned out , the $ 3:1 $ ratio was a crucial clue that let mendel crack the puzzle of inheritance . let 's take a closer look at what mendel figured out . mendel 's model of inheritance based on his results ( including that magic $ 3:1 $ ratio ) , mendel came up with a model for the inheritance of individual characteristics , such as flower color . in mendel 's model , parents pass along “ heritable factors , '' which we now call genes , that determine the traits of the offspring . each individual has two copies of a given gene , such as the gene for seed color ( y gene ) shown below . if these copies represent different versions , or alleles , of the gene , one allele—the dominant one—may hide the other allele—the recessive one . for seed color , the dominant yellow allele y hides the recessive green allele y . the set of alleles carried by an organism is known as its genotype . genotype determines phenotype , an organism 's observable features . when an organism has two copies of the same allele ( say , yy or yy ) , it is said to be homozygous for that gene . if , instead , it has two different copies ( like yy ) , we can say it is heterozygous . phenotype can also be affected by the environment in many real-life cases , though this did not have an impact on mendel 's work . mendel 's model : the law of segregation so far , so good . but this model alone does n't explain why mendel saw the exact patterns of inheritance he did . in particular , it does n't account for the $ 3:1 $ ratio . for that , we need mendel 's law of segregation . according to the law of segregation , only one of the two gene copies present in an organism is distributed to each gamete ( egg or sperm cell ) that it makes , and the allocation of the gene copies is random . when an egg and a sperm join in fertilization , they form a new organism , whose genotype consists of the alleles contained in the gametes . the diagram below illustrates this idea : the four-squared box shown for the $ \text f_2 $ generation is known as a punnett square . to prepare a punnett square , all possible gametes made by the parents are written along the top ( for the father ) and side ( for the mother ) of a grid . here , since it is self-fertilization , the same plant is both mother and father . the combinations of egg and sperm are then made in the boxes in the table , representing fertilization to make new individuals . because each square represents an equally likely event , we can determine genotype and phenotype ratios by counting the squares . the test cross mendel also came up with a way to figure out whether an organism with a dominant phenotype ( such as a yellow-seeded pea plant ) was a heterozygote ( yy ) or a homozygote ( yy ) . this technique is called a test cross and is still used by plant and animal breeders today . in a test cross , the organism with the dominant phenotype is crossed with an organism that is homozygous recessive ( e.g. , green-seeded ) : if the organism with the dominant phenotype is homozygous , then all of the $ \text f_1 $ offspring will get a dominant allele from that parent , be heterozygous , and show the dominant phenotype . if the organism with the dominant phenotype organism is instead a heterozygote , the $ \text f_1 $ offspring will be half heterozygotes ( dominant phenotype ) and half recessive homozygotes ( recessive phenotype ) . the fact that we get a $ 1:1 $ ratio in this second case is another confirmation of mendel ’ s law of segregation . is that mendel 's complete model of inheritance ? not quite ! we 've seen all of mendel 's model for the inheritance of single genes . however , mendel 's complete model also addressed whether genes for different characteristics ( such as flower color and seed shape ) influence each other 's inheritance . you can learn more about mendel 's model for the inheritance of multiple genes in the law of independent assortment article . one thing i find pretty amazing is that mendel was able to figure out his entire model of inheritance simply from his observations of pea plants . this was n't because he was some kind of crazy super genius , but rather , because he was very careful , persistent , and curious , and also because he thought about his results mathematically ( for instance , the $ 3:1 $ ratio ) . these are some of the qualities of a great scientist—ones that anyone , anywhere , can develop !
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in particular , it does n't account for the $ 3:1 $ ratio . for that , we need mendel 's law of segregation . according to the law of segregation , only one of the two gene copies present in an organism is distributed to each gamete ( egg or sperm cell ) that it makes , and the allocation of the gene copies is random .
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how did mendel derive his law of segregation from this monohybrid experiment ?
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key points : gregor mendel studied inheritance of traits in pea plants . he proposed a model where pairs of `` heritable elements , '' or genes , specified traits . genes come in different versions , or alleles . a dominant allele hides a recessive allele and determines the organism 's appearance . when an organism makes gametes , each gamete receives just one gene copy , which is selected randomly . this is known as the law of segregation . a punnett square can be used to predict genotypes ( allele combinations ) and phenotypes ( observable traits ) of offspring from genetic crosses . a test cross can be used to determine whether an organism with a dominant phenotype is homozygous or heterozygous . introduction today , we know that many of people 's characteristics , from hair color to height to risk of diabetes , are influenced by genes . we also know that genes are the way parents pass characteristics on to their children ( including things like dimples , or—in the case of me and my father—a terrible singing voice ) . in the last hundred years , we 've come to understand that genes are actually pieces of dna that are found on chromosomes and specify proteins . but did we always know those things ? not by a long shot ! about $ 150 $ years ago , a monk named gregor mendel published a paper that first proposed the existence of genes and presented a model for how they were inherited . mendel 's work was the first step on a long road , involving many hard-working scientists , that 's led to our present understanding of genes and what they do . in this article , we ’ ll trace the experiments and reasoning that led mendel to formulate his model for the inheritance of single genes . mendel 's model : it started with a $ 3:1 $ ratio mendel studied the genetics of pea plants , and he traced the inheritance of a variety of characteristics , including flower color , flower position , seed color , and seed shape . to do so , he started by crossing pure-breeding parent plants with different forms of a characteristic , such as violet and white flowers . pure-breeding just means that the plant will always make more offspring like itself , when self-fertilized over many generations . what results did mendel find in his crosses for flower color ? in the parental , or $ \text p $ generation , mendel crossed a pure-breeding violet-flowered plant to a pure-breeding white-flowered plant . when he gathered and planted the seeds produced in this cross , mendel found that $ 100 $ percent of the plants in the next generation , or $ \text f_1 $ generation , had violet flowers . conventional wisdom at that time would have predicted that the hybrid flowers should be pale violet—that is , that the parents ' traits should blend in the offspring . instead , mendel ’ s results showed that the white flower trait had completely disappeared . he called the trait that was visible in the $ \text f_1 $ generation ( violet flowers ) the dominant trait , and the trait that was hidden or lost ( white flowers ) the recessive trait . importantly , mendel did not stop his experimentation there . instead , he let the $ \text f_1 $ plants self-fertilize . among their offspring , called the $ \text f_2 $ generation , he found that $ 705 $ plants had violet flowers and $ 224 $ had white flowers . this was a ratio of $ 3.15 $ violet flowers to one white flower , or approximately $ 3:1 $ . this $ 3:1 $ ratio was no fluke . for the other six characteristics that mendel examined , both the $ \text f_1 $ and $ \text f_2 $ generations behaved in the same way they did for flower color . one of the two traits would disappear completely from the $ \text f_1 $ generation , only to reappear in the $ \text f_2 $ generation in a ratio of roughly $ 3:1 $ as it turned out , the $ 3:1 $ ratio was a crucial clue that let mendel crack the puzzle of inheritance . let 's take a closer look at what mendel figured out . mendel 's model of inheritance based on his results ( including that magic $ 3:1 $ ratio ) , mendel came up with a model for the inheritance of individual characteristics , such as flower color . in mendel 's model , parents pass along “ heritable factors , '' which we now call genes , that determine the traits of the offspring . each individual has two copies of a given gene , such as the gene for seed color ( y gene ) shown below . if these copies represent different versions , or alleles , of the gene , one allele—the dominant one—may hide the other allele—the recessive one . for seed color , the dominant yellow allele y hides the recessive green allele y . the set of alleles carried by an organism is known as its genotype . genotype determines phenotype , an organism 's observable features . when an organism has two copies of the same allele ( say , yy or yy ) , it is said to be homozygous for that gene . if , instead , it has two different copies ( like yy ) , we can say it is heterozygous . phenotype can also be affected by the environment in many real-life cases , though this did not have an impact on mendel 's work . mendel 's model : the law of segregation so far , so good . but this model alone does n't explain why mendel saw the exact patterns of inheritance he did . in particular , it does n't account for the $ 3:1 $ ratio . for that , we need mendel 's law of segregation . according to the law of segregation , only one of the two gene copies present in an organism is distributed to each gamete ( egg or sperm cell ) that it makes , and the allocation of the gene copies is random . when an egg and a sperm join in fertilization , they form a new organism , whose genotype consists of the alleles contained in the gametes . the diagram below illustrates this idea : the four-squared box shown for the $ \text f_2 $ generation is known as a punnett square . to prepare a punnett square , all possible gametes made by the parents are written along the top ( for the father ) and side ( for the mother ) of a grid . here , since it is self-fertilization , the same plant is both mother and father . the combinations of egg and sperm are then made in the boxes in the table , representing fertilization to make new individuals . because each square represents an equally likely event , we can determine genotype and phenotype ratios by counting the squares . the test cross mendel also came up with a way to figure out whether an organism with a dominant phenotype ( such as a yellow-seeded pea plant ) was a heterozygote ( yy ) or a homozygote ( yy ) . this technique is called a test cross and is still used by plant and animal breeders today . in a test cross , the organism with the dominant phenotype is crossed with an organism that is homozygous recessive ( e.g. , green-seeded ) : if the organism with the dominant phenotype is homozygous , then all of the $ \text f_1 $ offspring will get a dominant allele from that parent , be heterozygous , and show the dominant phenotype . if the organism with the dominant phenotype organism is instead a heterozygote , the $ \text f_1 $ offspring will be half heterozygotes ( dominant phenotype ) and half recessive homozygotes ( recessive phenotype ) . the fact that we get a $ 1:1 $ ratio in this second case is another confirmation of mendel ’ s law of segregation . is that mendel 's complete model of inheritance ? not quite ! we 've seen all of mendel 's model for the inheritance of single genes . however , mendel 's complete model also addressed whether genes for different characteristics ( such as flower color and seed shape ) influence each other 's inheritance . you can learn more about mendel 's model for the inheritance of multiple genes in the law of independent assortment article . one thing i find pretty amazing is that mendel was able to figure out his entire model of inheritance simply from his observations of pea plants . this was n't because he was some kind of crazy super genius , but rather , because he was very careful , persistent , and curious , and also because he thought about his results mathematically ( for instance , the $ 3:1 $ ratio ) . these are some of the qualities of a great scientist—ones that anyone , anywhere , can develop !
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this was n't because he was some kind of crazy super genius , but rather , because he was very careful , persistent , and curious , and also because he thought about his results mathematically ( for instance , the $ 3:1 $ ratio ) . these are some of the qualities of a great scientist—ones that anyone , anywhere , can develop !
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so would my grandparents be the f2 generation of my great great grandparents ?
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key points : gregor mendel studied inheritance of traits in pea plants . he proposed a model where pairs of `` heritable elements , '' or genes , specified traits . genes come in different versions , or alleles . a dominant allele hides a recessive allele and determines the organism 's appearance . when an organism makes gametes , each gamete receives just one gene copy , which is selected randomly . this is known as the law of segregation . a punnett square can be used to predict genotypes ( allele combinations ) and phenotypes ( observable traits ) of offspring from genetic crosses . a test cross can be used to determine whether an organism with a dominant phenotype is homozygous or heterozygous . introduction today , we know that many of people 's characteristics , from hair color to height to risk of diabetes , are influenced by genes . we also know that genes are the way parents pass characteristics on to their children ( including things like dimples , or—in the case of me and my father—a terrible singing voice ) . in the last hundred years , we 've come to understand that genes are actually pieces of dna that are found on chromosomes and specify proteins . but did we always know those things ? not by a long shot ! about $ 150 $ years ago , a monk named gregor mendel published a paper that first proposed the existence of genes and presented a model for how they were inherited . mendel 's work was the first step on a long road , involving many hard-working scientists , that 's led to our present understanding of genes and what they do . in this article , we ’ ll trace the experiments and reasoning that led mendel to formulate his model for the inheritance of single genes . mendel 's model : it started with a $ 3:1 $ ratio mendel studied the genetics of pea plants , and he traced the inheritance of a variety of characteristics , including flower color , flower position , seed color , and seed shape . to do so , he started by crossing pure-breeding parent plants with different forms of a characteristic , such as violet and white flowers . pure-breeding just means that the plant will always make more offspring like itself , when self-fertilized over many generations . what results did mendel find in his crosses for flower color ? in the parental , or $ \text p $ generation , mendel crossed a pure-breeding violet-flowered plant to a pure-breeding white-flowered plant . when he gathered and planted the seeds produced in this cross , mendel found that $ 100 $ percent of the plants in the next generation , or $ \text f_1 $ generation , had violet flowers . conventional wisdom at that time would have predicted that the hybrid flowers should be pale violet—that is , that the parents ' traits should blend in the offspring . instead , mendel ’ s results showed that the white flower trait had completely disappeared . he called the trait that was visible in the $ \text f_1 $ generation ( violet flowers ) the dominant trait , and the trait that was hidden or lost ( white flowers ) the recessive trait . importantly , mendel did not stop his experimentation there . instead , he let the $ \text f_1 $ plants self-fertilize . among their offspring , called the $ \text f_2 $ generation , he found that $ 705 $ plants had violet flowers and $ 224 $ had white flowers . this was a ratio of $ 3.15 $ violet flowers to one white flower , or approximately $ 3:1 $ . this $ 3:1 $ ratio was no fluke . for the other six characteristics that mendel examined , both the $ \text f_1 $ and $ \text f_2 $ generations behaved in the same way they did for flower color . one of the two traits would disappear completely from the $ \text f_1 $ generation , only to reappear in the $ \text f_2 $ generation in a ratio of roughly $ 3:1 $ as it turned out , the $ 3:1 $ ratio was a crucial clue that let mendel crack the puzzle of inheritance . let 's take a closer look at what mendel figured out . mendel 's model of inheritance based on his results ( including that magic $ 3:1 $ ratio ) , mendel came up with a model for the inheritance of individual characteristics , such as flower color . in mendel 's model , parents pass along “ heritable factors , '' which we now call genes , that determine the traits of the offspring . each individual has two copies of a given gene , such as the gene for seed color ( y gene ) shown below . if these copies represent different versions , or alleles , of the gene , one allele—the dominant one—may hide the other allele—the recessive one . for seed color , the dominant yellow allele y hides the recessive green allele y . the set of alleles carried by an organism is known as its genotype . genotype determines phenotype , an organism 's observable features . when an organism has two copies of the same allele ( say , yy or yy ) , it is said to be homozygous for that gene . if , instead , it has two different copies ( like yy ) , we can say it is heterozygous . phenotype can also be affected by the environment in many real-life cases , though this did not have an impact on mendel 's work . mendel 's model : the law of segregation so far , so good . but this model alone does n't explain why mendel saw the exact patterns of inheritance he did . in particular , it does n't account for the $ 3:1 $ ratio . for that , we need mendel 's law of segregation . according to the law of segregation , only one of the two gene copies present in an organism is distributed to each gamete ( egg or sperm cell ) that it makes , and the allocation of the gene copies is random . when an egg and a sperm join in fertilization , they form a new organism , whose genotype consists of the alleles contained in the gametes . the diagram below illustrates this idea : the four-squared box shown for the $ \text f_2 $ generation is known as a punnett square . to prepare a punnett square , all possible gametes made by the parents are written along the top ( for the father ) and side ( for the mother ) of a grid . here , since it is self-fertilization , the same plant is both mother and father . the combinations of egg and sperm are then made in the boxes in the table , representing fertilization to make new individuals . because each square represents an equally likely event , we can determine genotype and phenotype ratios by counting the squares . the test cross mendel also came up with a way to figure out whether an organism with a dominant phenotype ( such as a yellow-seeded pea plant ) was a heterozygote ( yy ) or a homozygote ( yy ) . this technique is called a test cross and is still used by plant and animal breeders today . in a test cross , the organism with the dominant phenotype is crossed with an organism that is homozygous recessive ( e.g. , green-seeded ) : if the organism with the dominant phenotype is homozygous , then all of the $ \text f_1 $ offspring will get a dominant allele from that parent , be heterozygous , and show the dominant phenotype . if the organism with the dominant phenotype organism is instead a heterozygote , the $ \text f_1 $ offspring will be half heterozygotes ( dominant phenotype ) and half recessive homozygotes ( recessive phenotype ) . the fact that we get a $ 1:1 $ ratio in this second case is another confirmation of mendel ’ s law of segregation . is that mendel 's complete model of inheritance ? not quite ! we 've seen all of mendel 's model for the inheritance of single genes . however , mendel 's complete model also addressed whether genes for different characteristics ( such as flower color and seed shape ) influence each other 's inheritance . you can learn more about mendel 's model for the inheritance of multiple genes in the law of independent assortment article . one thing i find pretty amazing is that mendel was able to figure out his entire model of inheritance simply from his observations of pea plants . this was n't because he was some kind of crazy super genius , but rather , because he was very careful , persistent , and curious , and also because he thought about his results mathematically ( for instance , the $ 3:1 $ ratio ) . these are some of the qualities of a great scientist—ones that anyone , anywhere , can develop !
|
when an organism makes gametes , each gamete receives just one gene copy , which is selected randomly . this is known as the law of segregation . a punnett square can be used to predict genotypes ( allele combinations ) and phenotypes ( observable traits ) of offspring from genetic crosses .
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in paragraph 3 , is sex-linked inheritance exclusively related to the law of segregation ?
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key points : gregor mendel studied inheritance of traits in pea plants . he proposed a model where pairs of `` heritable elements , '' or genes , specified traits . genes come in different versions , or alleles . a dominant allele hides a recessive allele and determines the organism 's appearance . when an organism makes gametes , each gamete receives just one gene copy , which is selected randomly . this is known as the law of segregation . a punnett square can be used to predict genotypes ( allele combinations ) and phenotypes ( observable traits ) of offspring from genetic crosses . a test cross can be used to determine whether an organism with a dominant phenotype is homozygous or heterozygous . introduction today , we know that many of people 's characteristics , from hair color to height to risk of diabetes , are influenced by genes . we also know that genes are the way parents pass characteristics on to their children ( including things like dimples , or—in the case of me and my father—a terrible singing voice ) . in the last hundred years , we 've come to understand that genes are actually pieces of dna that are found on chromosomes and specify proteins . but did we always know those things ? not by a long shot ! about $ 150 $ years ago , a monk named gregor mendel published a paper that first proposed the existence of genes and presented a model for how they were inherited . mendel 's work was the first step on a long road , involving many hard-working scientists , that 's led to our present understanding of genes and what they do . in this article , we ’ ll trace the experiments and reasoning that led mendel to formulate his model for the inheritance of single genes . mendel 's model : it started with a $ 3:1 $ ratio mendel studied the genetics of pea plants , and he traced the inheritance of a variety of characteristics , including flower color , flower position , seed color , and seed shape . to do so , he started by crossing pure-breeding parent plants with different forms of a characteristic , such as violet and white flowers . pure-breeding just means that the plant will always make more offspring like itself , when self-fertilized over many generations . what results did mendel find in his crosses for flower color ? in the parental , or $ \text p $ generation , mendel crossed a pure-breeding violet-flowered plant to a pure-breeding white-flowered plant . when he gathered and planted the seeds produced in this cross , mendel found that $ 100 $ percent of the plants in the next generation , or $ \text f_1 $ generation , had violet flowers . conventional wisdom at that time would have predicted that the hybrid flowers should be pale violet—that is , that the parents ' traits should blend in the offspring . instead , mendel ’ s results showed that the white flower trait had completely disappeared . he called the trait that was visible in the $ \text f_1 $ generation ( violet flowers ) the dominant trait , and the trait that was hidden or lost ( white flowers ) the recessive trait . importantly , mendel did not stop his experimentation there . instead , he let the $ \text f_1 $ plants self-fertilize . among their offspring , called the $ \text f_2 $ generation , he found that $ 705 $ plants had violet flowers and $ 224 $ had white flowers . this was a ratio of $ 3.15 $ violet flowers to one white flower , or approximately $ 3:1 $ . this $ 3:1 $ ratio was no fluke . for the other six characteristics that mendel examined , both the $ \text f_1 $ and $ \text f_2 $ generations behaved in the same way they did for flower color . one of the two traits would disappear completely from the $ \text f_1 $ generation , only to reappear in the $ \text f_2 $ generation in a ratio of roughly $ 3:1 $ as it turned out , the $ 3:1 $ ratio was a crucial clue that let mendel crack the puzzle of inheritance . let 's take a closer look at what mendel figured out . mendel 's model of inheritance based on his results ( including that magic $ 3:1 $ ratio ) , mendel came up with a model for the inheritance of individual characteristics , such as flower color . in mendel 's model , parents pass along “ heritable factors , '' which we now call genes , that determine the traits of the offspring . each individual has two copies of a given gene , such as the gene for seed color ( y gene ) shown below . if these copies represent different versions , or alleles , of the gene , one allele—the dominant one—may hide the other allele—the recessive one . for seed color , the dominant yellow allele y hides the recessive green allele y . the set of alleles carried by an organism is known as its genotype . genotype determines phenotype , an organism 's observable features . when an organism has two copies of the same allele ( say , yy or yy ) , it is said to be homozygous for that gene . if , instead , it has two different copies ( like yy ) , we can say it is heterozygous . phenotype can also be affected by the environment in many real-life cases , though this did not have an impact on mendel 's work . mendel 's model : the law of segregation so far , so good . but this model alone does n't explain why mendel saw the exact patterns of inheritance he did . in particular , it does n't account for the $ 3:1 $ ratio . for that , we need mendel 's law of segregation . according to the law of segregation , only one of the two gene copies present in an organism is distributed to each gamete ( egg or sperm cell ) that it makes , and the allocation of the gene copies is random . when an egg and a sperm join in fertilization , they form a new organism , whose genotype consists of the alleles contained in the gametes . the diagram below illustrates this idea : the four-squared box shown for the $ \text f_2 $ generation is known as a punnett square . to prepare a punnett square , all possible gametes made by the parents are written along the top ( for the father ) and side ( for the mother ) of a grid . here , since it is self-fertilization , the same plant is both mother and father . the combinations of egg and sperm are then made in the boxes in the table , representing fertilization to make new individuals . because each square represents an equally likely event , we can determine genotype and phenotype ratios by counting the squares . the test cross mendel also came up with a way to figure out whether an organism with a dominant phenotype ( such as a yellow-seeded pea plant ) was a heterozygote ( yy ) or a homozygote ( yy ) . this technique is called a test cross and is still used by plant and animal breeders today . in a test cross , the organism with the dominant phenotype is crossed with an organism that is homozygous recessive ( e.g. , green-seeded ) : if the organism with the dominant phenotype is homozygous , then all of the $ \text f_1 $ offspring will get a dominant allele from that parent , be heterozygous , and show the dominant phenotype . if the organism with the dominant phenotype organism is instead a heterozygote , the $ \text f_1 $ offspring will be half heterozygotes ( dominant phenotype ) and half recessive homozygotes ( recessive phenotype ) . the fact that we get a $ 1:1 $ ratio in this second case is another confirmation of mendel ’ s law of segregation . is that mendel 's complete model of inheritance ? not quite ! we 've seen all of mendel 's model for the inheritance of single genes . however , mendel 's complete model also addressed whether genes for different characteristics ( such as flower color and seed shape ) influence each other 's inheritance . you can learn more about mendel 's model for the inheritance of multiple genes in the law of independent assortment article . one thing i find pretty amazing is that mendel was able to figure out his entire model of inheritance simply from his observations of pea plants . this was n't because he was some kind of crazy super genius , but rather , because he was very careful , persistent , and curious , and also because he thought about his results mathematically ( for instance , the $ 3:1 $ ratio ) . these are some of the qualities of a great scientist—ones that anyone , anywhere , can develop !
|
when an organism makes gametes , each gamete receives just one gene copy , which is selected randomly . this is known as the law of segregation . a punnett square can be used to predict genotypes ( allele combinations ) and phenotypes ( observable traits ) of offspring from genetic crosses .
|
if not , does the law of segregation pertain to all types of inheritance ?
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key points : gregor mendel studied inheritance of traits in pea plants . he proposed a model where pairs of `` heritable elements , '' or genes , specified traits . genes come in different versions , or alleles . a dominant allele hides a recessive allele and determines the organism 's appearance . when an organism makes gametes , each gamete receives just one gene copy , which is selected randomly . this is known as the law of segregation . a punnett square can be used to predict genotypes ( allele combinations ) and phenotypes ( observable traits ) of offspring from genetic crosses . a test cross can be used to determine whether an organism with a dominant phenotype is homozygous or heterozygous . introduction today , we know that many of people 's characteristics , from hair color to height to risk of diabetes , are influenced by genes . we also know that genes are the way parents pass characteristics on to their children ( including things like dimples , or—in the case of me and my father—a terrible singing voice ) . in the last hundred years , we 've come to understand that genes are actually pieces of dna that are found on chromosomes and specify proteins . but did we always know those things ? not by a long shot ! about $ 150 $ years ago , a monk named gregor mendel published a paper that first proposed the existence of genes and presented a model for how they were inherited . mendel 's work was the first step on a long road , involving many hard-working scientists , that 's led to our present understanding of genes and what they do . in this article , we ’ ll trace the experiments and reasoning that led mendel to formulate his model for the inheritance of single genes . mendel 's model : it started with a $ 3:1 $ ratio mendel studied the genetics of pea plants , and he traced the inheritance of a variety of characteristics , including flower color , flower position , seed color , and seed shape . to do so , he started by crossing pure-breeding parent plants with different forms of a characteristic , such as violet and white flowers . pure-breeding just means that the plant will always make more offspring like itself , when self-fertilized over many generations . what results did mendel find in his crosses for flower color ? in the parental , or $ \text p $ generation , mendel crossed a pure-breeding violet-flowered plant to a pure-breeding white-flowered plant . when he gathered and planted the seeds produced in this cross , mendel found that $ 100 $ percent of the plants in the next generation , or $ \text f_1 $ generation , had violet flowers . conventional wisdom at that time would have predicted that the hybrid flowers should be pale violet—that is , that the parents ' traits should blend in the offspring . instead , mendel ’ s results showed that the white flower trait had completely disappeared . he called the trait that was visible in the $ \text f_1 $ generation ( violet flowers ) the dominant trait , and the trait that was hidden or lost ( white flowers ) the recessive trait . importantly , mendel did not stop his experimentation there . instead , he let the $ \text f_1 $ plants self-fertilize . among their offspring , called the $ \text f_2 $ generation , he found that $ 705 $ plants had violet flowers and $ 224 $ had white flowers . this was a ratio of $ 3.15 $ violet flowers to one white flower , or approximately $ 3:1 $ . this $ 3:1 $ ratio was no fluke . for the other six characteristics that mendel examined , both the $ \text f_1 $ and $ \text f_2 $ generations behaved in the same way they did for flower color . one of the two traits would disappear completely from the $ \text f_1 $ generation , only to reappear in the $ \text f_2 $ generation in a ratio of roughly $ 3:1 $ as it turned out , the $ 3:1 $ ratio was a crucial clue that let mendel crack the puzzle of inheritance . let 's take a closer look at what mendel figured out . mendel 's model of inheritance based on his results ( including that magic $ 3:1 $ ratio ) , mendel came up with a model for the inheritance of individual characteristics , such as flower color . in mendel 's model , parents pass along “ heritable factors , '' which we now call genes , that determine the traits of the offspring . each individual has two copies of a given gene , such as the gene for seed color ( y gene ) shown below . if these copies represent different versions , or alleles , of the gene , one allele—the dominant one—may hide the other allele—the recessive one . for seed color , the dominant yellow allele y hides the recessive green allele y . the set of alleles carried by an organism is known as its genotype . genotype determines phenotype , an organism 's observable features . when an organism has two copies of the same allele ( say , yy or yy ) , it is said to be homozygous for that gene . if , instead , it has two different copies ( like yy ) , we can say it is heterozygous . phenotype can also be affected by the environment in many real-life cases , though this did not have an impact on mendel 's work . mendel 's model : the law of segregation so far , so good . but this model alone does n't explain why mendel saw the exact patterns of inheritance he did . in particular , it does n't account for the $ 3:1 $ ratio . for that , we need mendel 's law of segregation . according to the law of segregation , only one of the two gene copies present in an organism is distributed to each gamete ( egg or sperm cell ) that it makes , and the allocation of the gene copies is random . when an egg and a sperm join in fertilization , they form a new organism , whose genotype consists of the alleles contained in the gametes . the diagram below illustrates this idea : the four-squared box shown for the $ \text f_2 $ generation is known as a punnett square . to prepare a punnett square , all possible gametes made by the parents are written along the top ( for the father ) and side ( for the mother ) of a grid . here , since it is self-fertilization , the same plant is both mother and father . the combinations of egg and sperm are then made in the boxes in the table , representing fertilization to make new individuals . because each square represents an equally likely event , we can determine genotype and phenotype ratios by counting the squares . the test cross mendel also came up with a way to figure out whether an organism with a dominant phenotype ( such as a yellow-seeded pea plant ) was a heterozygote ( yy ) or a homozygote ( yy ) . this technique is called a test cross and is still used by plant and animal breeders today . in a test cross , the organism with the dominant phenotype is crossed with an organism that is homozygous recessive ( e.g. , green-seeded ) : if the organism with the dominant phenotype is homozygous , then all of the $ \text f_1 $ offspring will get a dominant allele from that parent , be heterozygous , and show the dominant phenotype . if the organism with the dominant phenotype organism is instead a heterozygote , the $ \text f_1 $ offspring will be half heterozygotes ( dominant phenotype ) and half recessive homozygotes ( recessive phenotype ) . the fact that we get a $ 1:1 $ ratio in this second case is another confirmation of mendel ’ s law of segregation . is that mendel 's complete model of inheritance ? not quite ! we 've seen all of mendel 's model for the inheritance of single genes . however , mendel 's complete model also addressed whether genes for different characteristics ( such as flower color and seed shape ) influence each other 's inheritance . you can learn more about mendel 's model for the inheritance of multiple genes in the law of independent assortment article . one thing i find pretty amazing is that mendel was able to figure out his entire model of inheritance simply from his observations of pea plants . this was n't because he was some kind of crazy super genius , but rather , because he was very careful , persistent , and curious , and also because he thought about his results mathematically ( for instance , the $ 3:1 $ ratio ) . these are some of the qualities of a great scientist—ones that anyone , anywhere , can develop !
|
for seed color , the dominant yellow allele y hides the recessive green allele y . the set of alleles carried by an organism is known as its genotype . genotype determines phenotype , an organism 's observable features . when an organism has two copies of the same allele ( say , yy or yy ) , it is said to be homozygous for that gene .
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how can environment influence genotype ?
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key points : gregor mendel studied inheritance of traits in pea plants . he proposed a model where pairs of `` heritable elements , '' or genes , specified traits . genes come in different versions , or alleles . a dominant allele hides a recessive allele and determines the organism 's appearance . when an organism makes gametes , each gamete receives just one gene copy , which is selected randomly . this is known as the law of segregation . a punnett square can be used to predict genotypes ( allele combinations ) and phenotypes ( observable traits ) of offspring from genetic crosses . a test cross can be used to determine whether an organism with a dominant phenotype is homozygous or heterozygous . introduction today , we know that many of people 's characteristics , from hair color to height to risk of diabetes , are influenced by genes . we also know that genes are the way parents pass characteristics on to their children ( including things like dimples , or—in the case of me and my father—a terrible singing voice ) . in the last hundred years , we 've come to understand that genes are actually pieces of dna that are found on chromosomes and specify proteins . but did we always know those things ? not by a long shot ! about $ 150 $ years ago , a monk named gregor mendel published a paper that first proposed the existence of genes and presented a model for how they were inherited . mendel 's work was the first step on a long road , involving many hard-working scientists , that 's led to our present understanding of genes and what they do . in this article , we ’ ll trace the experiments and reasoning that led mendel to formulate his model for the inheritance of single genes . mendel 's model : it started with a $ 3:1 $ ratio mendel studied the genetics of pea plants , and he traced the inheritance of a variety of characteristics , including flower color , flower position , seed color , and seed shape . to do so , he started by crossing pure-breeding parent plants with different forms of a characteristic , such as violet and white flowers . pure-breeding just means that the plant will always make more offspring like itself , when self-fertilized over many generations . what results did mendel find in his crosses for flower color ? in the parental , or $ \text p $ generation , mendel crossed a pure-breeding violet-flowered plant to a pure-breeding white-flowered plant . when he gathered and planted the seeds produced in this cross , mendel found that $ 100 $ percent of the plants in the next generation , or $ \text f_1 $ generation , had violet flowers . conventional wisdom at that time would have predicted that the hybrid flowers should be pale violet—that is , that the parents ' traits should blend in the offspring . instead , mendel ’ s results showed that the white flower trait had completely disappeared . he called the trait that was visible in the $ \text f_1 $ generation ( violet flowers ) the dominant trait , and the trait that was hidden or lost ( white flowers ) the recessive trait . importantly , mendel did not stop his experimentation there . instead , he let the $ \text f_1 $ plants self-fertilize . among their offspring , called the $ \text f_2 $ generation , he found that $ 705 $ plants had violet flowers and $ 224 $ had white flowers . this was a ratio of $ 3.15 $ violet flowers to one white flower , or approximately $ 3:1 $ . this $ 3:1 $ ratio was no fluke . for the other six characteristics that mendel examined , both the $ \text f_1 $ and $ \text f_2 $ generations behaved in the same way they did for flower color . one of the two traits would disappear completely from the $ \text f_1 $ generation , only to reappear in the $ \text f_2 $ generation in a ratio of roughly $ 3:1 $ as it turned out , the $ 3:1 $ ratio was a crucial clue that let mendel crack the puzzle of inheritance . let 's take a closer look at what mendel figured out . mendel 's model of inheritance based on his results ( including that magic $ 3:1 $ ratio ) , mendel came up with a model for the inheritance of individual characteristics , such as flower color . in mendel 's model , parents pass along “ heritable factors , '' which we now call genes , that determine the traits of the offspring . each individual has two copies of a given gene , such as the gene for seed color ( y gene ) shown below . if these copies represent different versions , or alleles , of the gene , one allele—the dominant one—may hide the other allele—the recessive one . for seed color , the dominant yellow allele y hides the recessive green allele y . the set of alleles carried by an organism is known as its genotype . genotype determines phenotype , an organism 's observable features . when an organism has two copies of the same allele ( say , yy or yy ) , it is said to be homozygous for that gene . if , instead , it has two different copies ( like yy ) , we can say it is heterozygous . phenotype can also be affected by the environment in many real-life cases , though this did not have an impact on mendel 's work . mendel 's model : the law of segregation so far , so good . but this model alone does n't explain why mendel saw the exact patterns of inheritance he did . in particular , it does n't account for the $ 3:1 $ ratio . for that , we need mendel 's law of segregation . according to the law of segregation , only one of the two gene copies present in an organism is distributed to each gamete ( egg or sperm cell ) that it makes , and the allocation of the gene copies is random . when an egg and a sperm join in fertilization , they form a new organism , whose genotype consists of the alleles contained in the gametes . the diagram below illustrates this idea : the four-squared box shown for the $ \text f_2 $ generation is known as a punnett square . to prepare a punnett square , all possible gametes made by the parents are written along the top ( for the father ) and side ( for the mother ) of a grid . here , since it is self-fertilization , the same plant is both mother and father . the combinations of egg and sperm are then made in the boxes in the table , representing fertilization to make new individuals . because each square represents an equally likely event , we can determine genotype and phenotype ratios by counting the squares . the test cross mendel also came up with a way to figure out whether an organism with a dominant phenotype ( such as a yellow-seeded pea plant ) was a heterozygote ( yy ) or a homozygote ( yy ) . this technique is called a test cross and is still used by plant and animal breeders today . in a test cross , the organism with the dominant phenotype is crossed with an organism that is homozygous recessive ( e.g. , green-seeded ) : if the organism with the dominant phenotype is homozygous , then all of the $ \text f_1 $ offspring will get a dominant allele from that parent , be heterozygous , and show the dominant phenotype . if the organism with the dominant phenotype organism is instead a heterozygote , the $ \text f_1 $ offspring will be half heterozygotes ( dominant phenotype ) and half recessive homozygotes ( recessive phenotype ) . the fact that we get a $ 1:1 $ ratio in this second case is another confirmation of mendel ’ s law of segregation . is that mendel 's complete model of inheritance ? not quite ! we 've seen all of mendel 's model for the inheritance of single genes . however , mendel 's complete model also addressed whether genes for different characteristics ( such as flower color and seed shape ) influence each other 's inheritance . you can learn more about mendel 's model for the inheritance of multiple genes in the law of independent assortment article . one thing i find pretty amazing is that mendel was able to figure out his entire model of inheritance simply from his observations of pea plants . this was n't because he was some kind of crazy super genius , but rather , because he was very careful , persistent , and curious , and also because he thought about his results mathematically ( for instance , the $ 3:1 $ ratio ) . these are some of the qualities of a great scientist—ones that anyone , anywhere , can develop !
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in mendel 's model , parents pass along “ heritable factors , '' which we now call genes , that determine the traits of the offspring . each individual has two copies of a given gene , such as the gene for seed color ( y gene ) shown below . if these copies represent different versions , or alleles , of the gene , one allele—the dominant one—may hide the other allele—the recessive one .
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and what does it mean , in relation to genetic recombination , for an area on a gene to segregate together ?
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key points : gregor mendel studied inheritance of traits in pea plants . he proposed a model where pairs of `` heritable elements , '' or genes , specified traits . genes come in different versions , or alleles . a dominant allele hides a recessive allele and determines the organism 's appearance . when an organism makes gametes , each gamete receives just one gene copy , which is selected randomly . this is known as the law of segregation . a punnett square can be used to predict genotypes ( allele combinations ) and phenotypes ( observable traits ) of offspring from genetic crosses . a test cross can be used to determine whether an organism with a dominant phenotype is homozygous or heterozygous . introduction today , we know that many of people 's characteristics , from hair color to height to risk of diabetes , are influenced by genes . we also know that genes are the way parents pass characteristics on to their children ( including things like dimples , or—in the case of me and my father—a terrible singing voice ) . in the last hundred years , we 've come to understand that genes are actually pieces of dna that are found on chromosomes and specify proteins . but did we always know those things ? not by a long shot ! about $ 150 $ years ago , a monk named gregor mendel published a paper that first proposed the existence of genes and presented a model for how they were inherited . mendel 's work was the first step on a long road , involving many hard-working scientists , that 's led to our present understanding of genes and what they do . in this article , we ’ ll trace the experiments and reasoning that led mendel to formulate his model for the inheritance of single genes . mendel 's model : it started with a $ 3:1 $ ratio mendel studied the genetics of pea plants , and he traced the inheritance of a variety of characteristics , including flower color , flower position , seed color , and seed shape . to do so , he started by crossing pure-breeding parent plants with different forms of a characteristic , such as violet and white flowers . pure-breeding just means that the plant will always make more offspring like itself , when self-fertilized over many generations . what results did mendel find in his crosses for flower color ? in the parental , or $ \text p $ generation , mendel crossed a pure-breeding violet-flowered plant to a pure-breeding white-flowered plant . when he gathered and planted the seeds produced in this cross , mendel found that $ 100 $ percent of the plants in the next generation , or $ \text f_1 $ generation , had violet flowers . conventional wisdom at that time would have predicted that the hybrid flowers should be pale violet—that is , that the parents ' traits should blend in the offspring . instead , mendel ’ s results showed that the white flower trait had completely disappeared . he called the trait that was visible in the $ \text f_1 $ generation ( violet flowers ) the dominant trait , and the trait that was hidden or lost ( white flowers ) the recessive trait . importantly , mendel did not stop his experimentation there . instead , he let the $ \text f_1 $ plants self-fertilize . among their offspring , called the $ \text f_2 $ generation , he found that $ 705 $ plants had violet flowers and $ 224 $ had white flowers . this was a ratio of $ 3.15 $ violet flowers to one white flower , or approximately $ 3:1 $ . this $ 3:1 $ ratio was no fluke . for the other six characteristics that mendel examined , both the $ \text f_1 $ and $ \text f_2 $ generations behaved in the same way they did for flower color . one of the two traits would disappear completely from the $ \text f_1 $ generation , only to reappear in the $ \text f_2 $ generation in a ratio of roughly $ 3:1 $ as it turned out , the $ 3:1 $ ratio was a crucial clue that let mendel crack the puzzle of inheritance . let 's take a closer look at what mendel figured out . mendel 's model of inheritance based on his results ( including that magic $ 3:1 $ ratio ) , mendel came up with a model for the inheritance of individual characteristics , such as flower color . in mendel 's model , parents pass along “ heritable factors , '' which we now call genes , that determine the traits of the offspring . each individual has two copies of a given gene , such as the gene for seed color ( y gene ) shown below . if these copies represent different versions , or alleles , of the gene , one allele—the dominant one—may hide the other allele—the recessive one . for seed color , the dominant yellow allele y hides the recessive green allele y . the set of alleles carried by an organism is known as its genotype . genotype determines phenotype , an organism 's observable features . when an organism has two copies of the same allele ( say , yy or yy ) , it is said to be homozygous for that gene . if , instead , it has two different copies ( like yy ) , we can say it is heterozygous . phenotype can also be affected by the environment in many real-life cases , though this did not have an impact on mendel 's work . mendel 's model : the law of segregation so far , so good . but this model alone does n't explain why mendel saw the exact patterns of inheritance he did . in particular , it does n't account for the $ 3:1 $ ratio . for that , we need mendel 's law of segregation . according to the law of segregation , only one of the two gene copies present in an organism is distributed to each gamete ( egg or sperm cell ) that it makes , and the allocation of the gene copies is random . when an egg and a sperm join in fertilization , they form a new organism , whose genotype consists of the alleles contained in the gametes . the diagram below illustrates this idea : the four-squared box shown for the $ \text f_2 $ generation is known as a punnett square . to prepare a punnett square , all possible gametes made by the parents are written along the top ( for the father ) and side ( for the mother ) of a grid . here , since it is self-fertilization , the same plant is both mother and father . the combinations of egg and sperm are then made in the boxes in the table , representing fertilization to make new individuals . because each square represents an equally likely event , we can determine genotype and phenotype ratios by counting the squares . the test cross mendel also came up with a way to figure out whether an organism with a dominant phenotype ( such as a yellow-seeded pea plant ) was a heterozygote ( yy ) or a homozygote ( yy ) . this technique is called a test cross and is still used by plant and animal breeders today . in a test cross , the organism with the dominant phenotype is crossed with an organism that is homozygous recessive ( e.g. , green-seeded ) : if the organism with the dominant phenotype is homozygous , then all of the $ \text f_1 $ offspring will get a dominant allele from that parent , be heterozygous , and show the dominant phenotype . if the organism with the dominant phenotype organism is instead a heterozygote , the $ \text f_1 $ offspring will be half heterozygotes ( dominant phenotype ) and half recessive homozygotes ( recessive phenotype ) . the fact that we get a $ 1:1 $ ratio in this second case is another confirmation of mendel ’ s law of segregation . is that mendel 's complete model of inheritance ? not quite ! we 've seen all of mendel 's model for the inheritance of single genes . however , mendel 's complete model also addressed whether genes for different characteristics ( such as flower color and seed shape ) influence each other 's inheritance . you can learn more about mendel 's model for the inheritance of multiple genes in the law of independent assortment article . one thing i find pretty amazing is that mendel was able to figure out his entire model of inheritance simply from his observations of pea plants . this was n't because he was some kind of crazy super genius , but rather , because he was very careful , persistent , and curious , and also because he thought about his results mathematically ( for instance , the $ 3:1 $ ratio ) . these are some of the qualities of a great scientist—ones that anyone , anywhere , can develop !
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key points : gregor mendel studied inheritance of traits in pea plants . he proposed a model where pairs of `` heritable elements , '' or genes , specified traits . genes come in different versions , or alleles . a dominant allele hides a recessive allele and determines the organism 's appearance .
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can animal genes be replicated unto human genes ?
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key points : gregor mendel studied inheritance of traits in pea plants . he proposed a model where pairs of `` heritable elements , '' or genes , specified traits . genes come in different versions , or alleles . a dominant allele hides a recessive allele and determines the organism 's appearance . when an organism makes gametes , each gamete receives just one gene copy , which is selected randomly . this is known as the law of segregation . a punnett square can be used to predict genotypes ( allele combinations ) and phenotypes ( observable traits ) of offspring from genetic crosses . a test cross can be used to determine whether an organism with a dominant phenotype is homozygous or heterozygous . introduction today , we know that many of people 's characteristics , from hair color to height to risk of diabetes , are influenced by genes . we also know that genes are the way parents pass characteristics on to their children ( including things like dimples , or—in the case of me and my father—a terrible singing voice ) . in the last hundred years , we 've come to understand that genes are actually pieces of dna that are found on chromosomes and specify proteins . but did we always know those things ? not by a long shot ! about $ 150 $ years ago , a monk named gregor mendel published a paper that first proposed the existence of genes and presented a model for how they were inherited . mendel 's work was the first step on a long road , involving many hard-working scientists , that 's led to our present understanding of genes and what they do . in this article , we ’ ll trace the experiments and reasoning that led mendel to formulate his model for the inheritance of single genes . mendel 's model : it started with a $ 3:1 $ ratio mendel studied the genetics of pea plants , and he traced the inheritance of a variety of characteristics , including flower color , flower position , seed color , and seed shape . to do so , he started by crossing pure-breeding parent plants with different forms of a characteristic , such as violet and white flowers . pure-breeding just means that the plant will always make more offspring like itself , when self-fertilized over many generations . what results did mendel find in his crosses for flower color ? in the parental , or $ \text p $ generation , mendel crossed a pure-breeding violet-flowered plant to a pure-breeding white-flowered plant . when he gathered and planted the seeds produced in this cross , mendel found that $ 100 $ percent of the plants in the next generation , or $ \text f_1 $ generation , had violet flowers . conventional wisdom at that time would have predicted that the hybrid flowers should be pale violet—that is , that the parents ' traits should blend in the offspring . instead , mendel ’ s results showed that the white flower trait had completely disappeared . he called the trait that was visible in the $ \text f_1 $ generation ( violet flowers ) the dominant trait , and the trait that was hidden or lost ( white flowers ) the recessive trait . importantly , mendel did not stop his experimentation there . instead , he let the $ \text f_1 $ plants self-fertilize . among their offspring , called the $ \text f_2 $ generation , he found that $ 705 $ plants had violet flowers and $ 224 $ had white flowers . this was a ratio of $ 3.15 $ violet flowers to one white flower , or approximately $ 3:1 $ . this $ 3:1 $ ratio was no fluke . for the other six characteristics that mendel examined , both the $ \text f_1 $ and $ \text f_2 $ generations behaved in the same way they did for flower color . one of the two traits would disappear completely from the $ \text f_1 $ generation , only to reappear in the $ \text f_2 $ generation in a ratio of roughly $ 3:1 $ as it turned out , the $ 3:1 $ ratio was a crucial clue that let mendel crack the puzzle of inheritance . let 's take a closer look at what mendel figured out . mendel 's model of inheritance based on his results ( including that magic $ 3:1 $ ratio ) , mendel came up with a model for the inheritance of individual characteristics , such as flower color . in mendel 's model , parents pass along “ heritable factors , '' which we now call genes , that determine the traits of the offspring . each individual has two copies of a given gene , such as the gene for seed color ( y gene ) shown below . if these copies represent different versions , or alleles , of the gene , one allele—the dominant one—may hide the other allele—the recessive one . for seed color , the dominant yellow allele y hides the recessive green allele y . the set of alleles carried by an organism is known as its genotype . genotype determines phenotype , an organism 's observable features . when an organism has two copies of the same allele ( say , yy or yy ) , it is said to be homozygous for that gene . if , instead , it has two different copies ( like yy ) , we can say it is heterozygous . phenotype can also be affected by the environment in many real-life cases , though this did not have an impact on mendel 's work . mendel 's model : the law of segregation so far , so good . but this model alone does n't explain why mendel saw the exact patterns of inheritance he did . in particular , it does n't account for the $ 3:1 $ ratio . for that , we need mendel 's law of segregation . according to the law of segregation , only one of the two gene copies present in an organism is distributed to each gamete ( egg or sperm cell ) that it makes , and the allocation of the gene copies is random . when an egg and a sperm join in fertilization , they form a new organism , whose genotype consists of the alleles contained in the gametes . the diagram below illustrates this idea : the four-squared box shown for the $ \text f_2 $ generation is known as a punnett square . to prepare a punnett square , all possible gametes made by the parents are written along the top ( for the father ) and side ( for the mother ) of a grid . here , since it is self-fertilization , the same plant is both mother and father . the combinations of egg and sperm are then made in the boxes in the table , representing fertilization to make new individuals . because each square represents an equally likely event , we can determine genotype and phenotype ratios by counting the squares . the test cross mendel also came up with a way to figure out whether an organism with a dominant phenotype ( such as a yellow-seeded pea plant ) was a heterozygote ( yy ) or a homozygote ( yy ) . this technique is called a test cross and is still used by plant and animal breeders today . in a test cross , the organism with the dominant phenotype is crossed with an organism that is homozygous recessive ( e.g. , green-seeded ) : if the organism with the dominant phenotype is homozygous , then all of the $ \text f_1 $ offspring will get a dominant allele from that parent , be heterozygous , and show the dominant phenotype . if the organism with the dominant phenotype organism is instead a heterozygote , the $ \text f_1 $ offspring will be half heterozygotes ( dominant phenotype ) and half recessive homozygotes ( recessive phenotype ) . the fact that we get a $ 1:1 $ ratio in this second case is another confirmation of mendel ’ s law of segregation . is that mendel 's complete model of inheritance ? not quite ! we 've seen all of mendel 's model for the inheritance of single genes . however , mendel 's complete model also addressed whether genes for different characteristics ( such as flower color and seed shape ) influence each other 's inheritance . you can learn more about mendel 's model for the inheritance of multiple genes in the law of independent assortment article . one thing i find pretty amazing is that mendel was able to figure out his entire model of inheritance simply from his observations of pea plants . this was n't because he was some kind of crazy super genius , but rather , because he was very careful , persistent , and curious , and also because he thought about his results mathematically ( for instance , the $ 3:1 $ ratio ) . these are some of the qualities of a great scientist—ones that anyone , anywhere , can develop !
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this is known as the law of segregation . a punnett square can be used to predict genotypes ( allele combinations ) and phenotypes ( observable traits ) of offspring from genetic crosses . a test cross can be used to determine whether an organism with a dominant phenotype is homozygous or heterozygous .
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why do we do punnett square ?
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key points : gregor mendel studied inheritance of traits in pea plants . he proposed a model where pairs of `` heritable elements , '' or genes , specified traits . genes come in different versions , or alleles . a dominant allele hides a recessive allele and determines the organism 's appearance . when an organism makes gametes , each gamete receives just one gene copy , which is selected randomly . this is known as the law of segregation . a punnett square can be used to predict genotypes ( allele combinations ) and phenotypes ( observable traits ) of offspring from genetic crosses . a test cross can be used to determine whether an organism with a dominant phenotype is homozygous or heterozygous . introduction today , we know that many of people 's characteristics , from hair color to height to risk of diabetes , are influenced by genes . we also know that genes are the way parents pass characteristics on to their children ( including things like dimples , or—in the case of me and my father—a terrible singing voice ) . in the last hundred years , we 've come to understand that genes are actually pieces of dna that are found on chromosomes and specify proteins . but did we always know those things ? not by a long shot ! about $ 150 $ years ago , a monk named gregor mendel published a paper that first proposed the existence of genes and presented a model for how they were inherited . mendel 's work was the first step on a long road , involving many hard-working scientists , that 's led to our present understanding of genes and what they do . in this article , we ’ ll trace the experiments and reasoning that led mendel to formulate his model for the inheritance of single genes . mendel 's model : it started with a $ 3:1 $ ratio mendel studied the genetics of pea plants , and he traced the inheritance of a variety of characteristics , including flower color , flower position , seed color , and seed shape . to do so , he started by crossing pure-breeding parent plants with different forms of a characteristic , such as violet and white flowers . pure-breeding just means that the plant will always make more offspring like itself , when self-fertilized over many generations . what results did mendel find in his crosses for flower color ? in the parental , or $ \text p $ generation , mendel crossed a pure-breeding violet-flowered plant to a pure-breeding white-flowered plant . when he gathered and planted the seeds produced in this cross , mendel found that $ 100 $ percent of the plants in the next generation , or $ \text f_1 $ generation , had violet flowers . conventional wisdom at that time would have predicted that the hybrid flowers should be pale violet—that is , that the parents ' traits should blend in the offspring . instead , mendel ’ s results showed that the white flower trait had completely disappeared . he called the trait that was visible in the $ \text f_1 $ generation ( violet flowers ) the dominant trait , and the trait that was hidden or lost ( white flowers ) the recessive trait . importantly , mendel did not stop his experimentation there . instead , he let the $ \text f_1 $ plants self-fertilize . among their offspring , called the $ \text f_2 $ generation , he found that $ 705 $ plants had violet flowers and $ 224 $ had white flowers . this was a ratio of $ 3.15 $ violet flowers to one white flower , or approximately $ 3:1 $ . this $ 3:1 $ ratio was no fluke . for the other six characteristics that mendel examined , both the $ \text f_1 $ and $ \text f_2 $ generations behaved in the same way they did for flower color . one of the two traits would disappear completely from the $ \text f_1 $ generation , only to reappear in the $ \text f_2 $ generation in a ratio of roughly $ 3:1 $ as it turned out , the $ 3:1 $ ratio was a crucial clue that let mendel crack the puzzle of inheritance . let 's take a closer look at what mendel figured out . mendel 's model of inheritance based on his results ( including that magic $ 3:1 $ ratio ) , mendel came up with a model for the inheritance of individual characteristics , such as flower color . in mendel 's model , parents pass along “ heritable factors , '' which we now call genes , that determine the traits of the offspring . each individual has two copies of a given gene , such as the gene for seed color ( y gene ) shown below . if these copies represent different versions , or alleles , of the gene , one allele—the dominant one—may hide the other allele—the recessive one . for seed color , the dominant yellow allele y hides the recessive green allele y . the set of alleles carried by an organism is known as its genotype . genotype determines phenotype , an organism 's observable features . when an organism has two copies of the same allele ( say , yy or yy ) , it is said to be homozygous for that gene . if , instead , it has two different copies ( like yy ) , we can say it is heterozygous . phenotype can also be affected by the environment in many real-life cases , though this did not have an impact on mendel 's work . mendel 's model : the law of segregation so far , so good . but this model alone does n't explain why mendel saw the exact patterns of inheritance he did . in particular , it does n't account for the $ 3:1 $ ratio . for that , we need mendel 's law of segregation . according to the law of segregation , only one of the two gene copies present in an organism is distributed to each gamete ( egg or sperm cell ) that it makes , and the allocation of the gene copies is random . when an egg and a sperm join in fertilization , they form a new organism , whose genotype consists of the alleles contained in the gametes . the diagram below illustrates this idea : the four-squared box shown for the $ \text f_2 $ generation is known as a punnett square . to prepare a punnett square , all possible gametes made by the parents are written along the top ( for the father ) and side ( for the mother ) of a grid . here , since it is self-fertilization , the same plant is both mother and father . the combinations of egg and sperm are then made in the boxes in the table , representing fertilization to make new individuals . because each square represents an equally likely event , we can determine genotype and phenotype ratios by counting the squares . the test cross mendel also came up with a way to figure out whether an organism with a dominant phenotype ( such as a yellow-seeded pea plant ) was a heterozygote ( yy ) or a homozygote ( yy ) . this technique is called a test cross and is still used by plant and animal breeders today . in a test cross , the organism with the dominant phenotype is crossed with an organism that is homozygous recessive ( e.g. , green-seeded ) : if the organism with the dominant phenotype is homozygous , then all of the $ \text f_1 $ offspring will get a dominant allele from that parent , be heterozygous , and show the dominant phenotype . if the organism with the dominant phenotype organism is instead a heterozygote , the $ \text f_1 $ offspring will be half heterozygotes ( dominant phenotype ) and half recessive homozygotes ( recessive phenotype ) . the fact that we get a $ 1:1 $ ratio in this second case is another confirmation of mendel ’ s law of segregation . is that mendel 's complete model of inheritance ? not quite ! we 've seen all of mendel 's model for the inheritance of single genes . however , mendel 's complete model also addressed whether genes for different characteristics ( such as flower color and seed shape ) influence each other 's inheritance . you can learn more about mendel 's model for the inheritance of multiple genes in the law of independent assortment article . one thing i find pretty amazing is that mendel was able to figure out his entire model of inheritance simply from his observations of pea plants . this was n't because he was some kind of crazy super genius , but rather , because he was very careful , persistent , and curious , and also because he thought about his results mathematically ( for instance , the $ 3:1 $ ratio ) . these are some of the qualities of a great scientist—ones that anyone , anywhere , can develop !
|
the combinations of egg and sperm are then made in the boxes in the table , representing fertilization to make new individuals . because each square represents an equally likely event , we can determine genotype and phenotype ratios by counting the squares . the test cross mendel also came up with a way to figure out whether an organism with a dominant phenotype ( such as a yellow-seeded pea plant ) was a heterozygote ( yy ) or a homozygote ( yy ) .
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are we going to use punnett squares ever in life ?
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key points : gregor mendel studied inheritance of traits in pea plants . he proposed a model where pairs of `` heritable elements , '' or genes , specified traits . genes come in different versions , or alleles . a dominant allele hides a recessive allele and determines the organism 's appearance . when an organism makes gametes , each gamete receives just one gene copy , which is selected randomly . this is known as the law of segregation . a punnett square can be used to predict genotypes ( allele combinations ) and phenotypes ( observable traits ) of offspring from genetic crosses . a test cross can be used to determine whether an organism with a dominant phenotype is homozygous or heterozygous . introduction today , we know that many of people 's characteristics , from hair color to height to risk of diabetes , are influenced by genes . we also know that genes are the way parents pass characteristics on to their children ( including things like dimples , or—in the case of me and my father—a terrible singing voice ) . in the last hundred years , we 've come to understand that genes are actually pieces of dna that are found on chromosomes and specify proteins . but did we always know those things ? not by a long shot ! about $ 150 $ years ago , a monk named gregor mendel published a paper that first proposed the existence of genes and presented a model for how they were inherited . mendel 's work was the first step on a long road , involving many hard-working scientists , that 's led to our present understanding of genes and what they do . in this article , we ’ ll trace the experiments and reasoning that led mendel to formulate his model for the inheritance of single genes . mendel 's model : it started with a $ 3:1 $ ratio mendel studied the genetics of pea plants , and he traced the inheritance of a variety of characteristics , including flower color , flower position , seed color , and seed shape . to do so , he started by crossing pure-breeding parent plants with different forms of a characteristic , such as violet and white flowers . pure-breeding just means that the plant will always make more offspring like itself , when self-fertilized over many generations . what results did mendel find in his crosses for flower color ? in the parental , or $ \text p $ generation , mendel crossed a pure-breeding violet-flowered plant to a pure-breeding white-flowered plant . when he gathered and planted the seeds produced in this cross , mendel found that $ 100 $ percent of the plants in the next generation , or $ \text f_1 $ generation , had violet flowers . conventional wisdom at that time would have predicted that the hybrid flowers should be pale violet—that is , that the parents ' traits should blend in the offspring . instead , mendel ’ s results showed that the white flower trait had completely disappeared . he called the trait that was visible in the $ \text f_1 $ generation ( violet flowers ) the dominant trait , and the trait that was hidden or lost ( white flowers ) the recessive trait . importantly , mendel did not stop his experimentation there . instead , he let the $ \text f_1 $ plants self-fertilize . among their offspring , called the $ \text f_2 $ generation , he found that $ 705 $ plants had violet flowers and $ 224 $ had white flowers . this was a ratio of $ 3.15 $ violet flowers to one white flower , or approximately $ 3:1 $ . this $ 3:1 $ ratio was no fluke . for the other six characteristics that mendel examined , both the $ \text f_1 $ and $ \text f_2 $ generations behaved in the same way they did for flower color . one of the two traits would disappear completely from the $ \text f_1 $ generation , only to reappear in the $ \text f_2 $ generation in a ratio of roughly $ 3:1 $ as it turned out , the $ 3:1 $ ratio was a crucial clue that let mendel crack the puzzle of inheritance . let 's take a closer look at what mendel figured out . mendel 's model of inheritance based on his results ( including that magic $ 3:1 $ ratio ) , mendel came up with a model for the inheritance of individual characteristics , such as flower color . in mendel 's model , parents pass along “ heritable factors , '' which we now call genes , that determine the traits of the offspring . each individual has two copies of a given gene , such as the gene for seed color ( y gene ) shown below . if these copies represent different versions , or alleles , of the gene , one allele—the dominant one—may hide the other allele—the recessive one . for seed color , the dominant yellow allele y hides the recessive green allele y . the set of alleles carried by an organism is known as its genotype . genotype determines phenotype , an organism 's observable features . when an organism has two copies of the same allele ( say , yy or yy ) , it is said to be homozygous for that gene . if , instead , it has two different copies ( like yy ) , we can say it is heterozygous . phenotype can also be affected by the environment in many real-life cases , though this did not have an impact on mendel 's work . mendel 's model : the law of segregation so far , so good . but this model alone does n't explain why mendel saw the exact patterns of inheritance he did . in particular , it does n't account for the $ 3:1 $ ratio . for that , we need mendel 's law of segregation . according to the law of segregation , only one of the two gene copies present in an organism is distributed to each gamete ( egg or sperm cell ) that it makes , and the allocation of the gene copies is random . when an egg and a sperm join in fertilization , they form a new organism , whose genotype consists of the alleles contained in the gametes . the diagram below illustrates this idea : the four-squared box shown for the $ \text f_2 $ generation is known as a punnett square . to prepare a punnett square , all possible gametes made by the parents are written along the top ( for the father ) and side ( for the mother ) of a grid . here , since it is self-fertilization , the same plant is both mother and father . the combinations of egg and sperm are then made in the boxes in the table , representing fertilization to make new individuals . because each square represents an equally likely event , we can determine genotype and phenotype ratios by counting the squares . the test cross mendel also came up with a way to figure out whether an organism with a dominant phenotype ( such as a yellow-seeded pea plant ) was a heterozygote ( yy ) or a homozygote ( yy ) . this technique is called a test cross and is still used by plant and animal breeders today . in a test cross , the organism with the dominant phenotype is crossed with an organism that is homozygous recessive ( e.g. , green-seeded ) : if the organism with the dominant phenotype is homozygous , then all of the $ \text f_1 $ offspring will get a dominant allele from that parent , be heterozygous , and show the dominant phenotype . if the organism with the dominant phenotype organism is instead a heterozygote , the $ \text f_1 $ offspring will be half heterozygotes ( dominant phenotype ) and half recessive homozygotes ( recessive phenotype ) . the fact that we get a $ 1:1 $ ratio in this second case is another confirmation of mendel ’ s law of segregation . is that mendel 's complete model of inheritance ? not quite ! we 've seen all of mendel 's model for the inheritance of single genes . however , mendel 's complete model also addressed whether genes for different characteristics ( such as flower color and seed shape ) influence each other 's inheritance . you can learn more about mendel 's model for the inheritance of multiple genes in the law of independent assortment article . one thing i find pretty amazing is that mendel was able to figure out his entire model of inheritance simply from his observations of pea plants . this was n't because he was some kind of crazy super genius , but rather , because he was very careful , persistent , and curious , and also because he thought about his results mathematically ( for instance , the $ 3:1 $ ratio ) . these are some of the qualities of a great scientist—ones that anyone , anywhere , can develop !
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when an organism makes gametes , each gamete receives just one gene copy , which is selected randomly . this is known as the law of segregation . a punnett square can be used to predict genotypes ( allele combinations ) and phenotypes ( observable traits ) of offspring from genetic crosses .
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in your law of segregation panel of explanation ( which can be hidden or otherwise and ) which occurs just before the test cross section , you refer to a pp genotype which i 'm pretty sure should be a yy genotype , could you clarify please ?
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a monumental tube of lipstick sprouting from a military vehicle appeared , uninvited , on the campus of yale university amidst the 1969 student protests against the vietnam war . while the sculpture may have seemed like a playful , if elaborate artistic joke , claes oldenburg ’ s lipstick ( ascending ) on caterpillar tracks was also deeply critical . oldenburg made the 24-foot-high sculpture in collaboration with architecture students at his alma mater and then surreptitiously delivered it to yale ’ s beinecke plaza . in beinecke plaza , the sculpture overlooked both the office of yale ’ s president and a prominent world war i memorial . lipstick ( ascending ) on caterpillar tracks claimed a visible space for the anti-war movement while also poking fun at the solemnity of the plaza . the sculpture served as a stage and backdrop for several subsequent student protests . oldenburg and the architeciture students never intended for the original lipstick ( ascending ) on caterpillar tracks sculpture to be permanent . they made the base of plywood , and the red vinyl tip of the lipstick could be comically inflated and deflated—although the balloon mechanism didn ’ t always work . the original remained in beinecke plaza for ten months before oldenburg removed it in order to remake the form in metal . the resulting sculpture was placed in a less-prominent spot on yale ’ s campus , where it remains to this day . gender , consumerism , and war oldenburg had experimented with lipstick forms earlier in the 1960s , pasting catalog images of lipstick onto postcards of london ’ s picadilly circus . the resulting collages showed lipstick tubes looming like massive pillars over picadilly ’ s plaza . in the yale sculpture , the artist combined the highly “ feminine ” product with the “ masculine ” machinery of war . in doing so , he playfully critiqued both the hawkish , hyper-masculine rhetoric of the military and the blatant consumerism of the united states . in addition to its feminine associations , the large lipstick tube is phallic and bullet-like , making the benign beauty product seem masculine or even violent . the juxtaposition implied that the u.s. obsession with beauty and consumption both fueled and distracted from the ongoing violence in vietnam . going public oldenburg had been designing large-scale , vinyl versions of household objects since his green gallery exhibition in 1962 . he had created collages and drawings that played with the notion of massive domestic objects in public places , but lipstick was his first large-scale public artwork . oldenburg went on to make several other public sculptures that enlarged everyday domestic items to monumental dimensions . for example , he rendered a clothespin on the scale of an ancient egyptian obelisk in a 1976 sculpture for philadelphia , pennsylvania ( below ) . by bringing both domestic and military objects into a public space , lipstick ( ascending ) on caterpillar tracks blurred the lines between public and private , and between the war in vietnam and culture of the united states . in doing so , it upheld oldenburg ’ s 1961 declaration that “ i am for an art that is political-erotical-mystical , that does something other than sit on its ass in a museum [ … ] i am for an art that imitates the human , that is comic , if necessary , or violent , or whatever is necessary [ … ] . ” [ 1 ] essay by mya dosch [ 1 ] claes oldenburg , `` i am for an art ... '' in environments , situations , spaces ( new york : martha jackson gallery , 1961 ) ; reprinted in an expanded version in oldenburg and emmett williams , eds. , store days : documents from the store ( 1961 ) and ray gun theater ( 1962 ) ( new york : something else press , 1967 ) , 39-42 . additional resources : this sculpture at yale university artist biography and related sculpture at tate britain
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for example , he rendered a clothespin on the scale of an ancient egyptian obelisk in a 1976 sculpture for philadelphia , pennsylvania ( below ) . by bringing both domestic and military objects into a public space , lipstick ( ascending ) on caterpillar tracks blurred the lines between public and private , and between the war in vietnam and culture of the united states . in doing so , it upheld oldenburg ’ s 1961 declaration that “ i am for an art that is political-erotical-mystical , that does something other than sit on its ass in a museum [ … ] i am for an art that imitates the human , that is comic , if necessary , or violent , or whatever is necessary [ … ] . ” [ 1 ] essay by mya dosch [ 1 ] claes oldenburg , `` i am for an art ... '' in environments , situations , spaces ( new york : martha jackson gallery , 1961 ) ; reprinted in an expanded version in oldenburg and emmett williams , eds. , store days : documents from the store ( 1961 ) and ray gun theater ( 1962 ) ( new york : something else press , 1967 ) , 39-42 . additional resources : this sculpture at yale university artist biography and related sculpture at tate britain
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could this art have been considered an insult to the troops who lost their lives in vietnam ?
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there are two versions of leonardo 's virgin of the rocks ( the version in the louvre was painted first ) . these two paintings are a good place to start to define the qualities of the new style of the high renaissance . leonardo painted both in milan , where he had moved from florence . normally when we have seen mary and christ ( in , for example , paintings by lippi and giotto ) , mary has been enthroned as the queen of heaven . here , in contrast , we see mary seated on the ground . this type of representation of mary is referred to as the madonna of humility . mary has her right arm around the infant saint john the baptist who is making a gesture of prayer to the christ child . the christ child in turn blesses st. john . mary 's left hand hovers protectively over the head of her son while an angel looks out and points to st. john . the figures are all located in a fabulous and mystical landscape with rivers that seem to lead nowhere and bizarre rock formations that recall the dolomite mountains of northeastern italy . in the foreground we see carefully observed and precisely rendered plants and flowers . we immediately notice mary 's ideal beauty and the graceful way in which she moves , features typical of the high renaissance . this is the first time that an italian renaissance artist has completely abandoned halos . fra filippo lippi reduced the halo to a narrow ring around mary 's head . clearly the unreal , symbolic nature of the halo was antithetical to the realism of the renaissance . it was , in a way , a necessary holdover from the middle ages : how else to indicate a figure 's divinity ? but leonardo found another way to indicate divinity—by giving the figures ideal beauty and grace . after all , we would never mistake leonardo 's group of figures for an ordinary picnic—the way the lippi 's painting of the madonna and child with angels almost looks like a family portrait . with leonardo 's virgin of the rocks , we are clearly looking at a mystical vision of mary , christ , john the baptist and an angel in heaven . the unified composition we can see that leonardo grouped the figures together within a geometric shape of a pyramid ( a pyramid instead of triangle because leonardo is very concerned with creating an illusion of space—and a pyramid is three dimensional ) . he also has the figures gesturing and looking at each other . both of these innovations serve to unify the composition . this is an important difference from paintings of the early renaissance where the figures often looked more separate from one another . another way to think about this is to look at the angel that leonardo painted in this work by his teacher verocchio . leonardo 's angel has a more complex pose . things that artists were just learning how to do in the early renaissance ( like contrapposto ) are now easy for the artists of the high renaissance . as a result , artists of the high renaissance can do more with the body—make it more complex , more elegant and more graceful . similarly , the compositions of the paintings of the high renaissance are more complex and sophisticated than the compositions of the early renaissance—figures interact with gestures and glances , and are often interwoven and set within the shape of a pyramid . essay by dr. beth harris and dr. steven zucker additional resources this painting at the national gallery this painting at the louvre videos on leonardo ( from the national gallery , london ) national gallery page on the conservation of the painting in london national gallery video on the restoration of the painting in london national gallery video/podcast on the two versions of this painting coline milliard , '' analyzing 5 differences between da vinci 's twin `` virgin of the rocks '' masterpieces '' from artinfo 22/08/2011 .
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similarly , the compositions of the paintings of the high renaissance are more complex and sophisticated than the compositions of the early renaissance—figures interact with gestures and glances , and are often interwoven and set within the shape of a pyramid . essay by dr. beth harris and dr. steven zucker additional resources this painting at the national gallery this painting at the louvre videos on leonardo ( from the national gallery , london ) national gallery page on the conservation of the painting in london national gallery video on the restoration of the painting in london national gallery video/podcast on the two versions of this painting coline milliard , '' analyzing 5 differences between da vinci 's twin `` virgin of the rocks '' masterpieces '' from artinfo 22/08/2011 .
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why did leonardo da vinci paint essentially the same , or at least very similar paintings twice , as we can see with the louvre 's version and the national gallery in london 's version of the virgin of the rocks ?
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there are two versions of leonardo 's virgin of the rocks ( the version in the louvre was painted first ) . these two paintings are a good place to start to define the qualities of the new style of the high renaissance . leonardo painted both in milan , where he had moved from florence . normally when we have seen mary and christ ( in , for example , paintings by lippi and giotto ) , mary has been enthroned as the queen of heaven . here , in contrast , we see mary seated on the ground . this type of representation of mary is referred to as the madonna of humility . mary has her right arm around the infant saint john the baptist who is making a gesture of prayer to the christ child . the christ child in turn blesses st. john . mary 's left hand hovers protectively over the head of her son while an angel looks out and points to st. john . the figures are all located in a fabulous and mystical landscape with rivers that seem to lead nowhere and bizarre rock formations that recall the dolomite mountains of northeastern italy . in the foreground we see carefully observed and precisely rendered plants and flowers . we immediately notice mary 's ideal beauty and the graceful way in which she moves , features typical of the high renaissance . this is the first time that an italian renaissance artist has completely abandoned halos . fra filippo lippi reduced the halo to a narrow ring around mary 's head . clearly the unreal , symbolic nature of the halo was antithetical to the realism of the renaissance . it was , in a way , a necessary holdover from the middle ages : how else to indicate a figure 's divinity ? but leonardo found another way to indicate divinity—by giving the figures ideal beauty and grace . after all , we would never mistake leonardo 's group of figures for an ordinary picnic—the way the lippi 's painting of the madonna and child with angels almost looks like a family portrait . with leonardo 's virgin of the rocks , we are clearly looking at a mystical vision of mary , christ , john the baptist and an angel in heaven . the unified composition we can see that leonardo grouped the figures together within a geometric shape of a pyramid ( a pyramid instead of triangle because leonardo is very concerned with creating an illusion of space—and a pyramid is three dimensional ) . he also has the figures gesturing and looking at each other . both of these innovations serve to unify the composition . this is an important difference from paintings of the early renaissance where the figures often looked more separate from one another . another way to think about this is to look at the angel that leonardo painted in this work by his teacher verocchio . leonardo 's angel has a more complex pose . things that artists were just learning how to do in the early renaissance ( like contrapposto ) are now easy for the artists of the high renaissance . as a result , artists of the high renaissance can do more with the body—make it more complex , more elegant and more graceful . similarly , the compositions of the paintings of the high renaissance are more complex and sophisticated than the compositions of the early renaissance—figures interact with gestures and glances , and are often interwoven and set within the shape of a pyramid . essay by dr. beth harris and dr. steven zucker additional resources this painting at the national gallery this painting at the louvre videos on leonardo ( from the national gallery , london ) national gallery page on the conservation of the painting in london national gallery video on the restoration of the painting in london national gallery video/podcast on the two versions of this painting coline milliard , '' analyzing 5 differences between da vinci 's twin `` virgin of the rocks '' masterpieces '' from artinfo 22/08/2011 .
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in the foreground we see carefully observed and precisely rendered plants and flowers . we immediately notice mary 's ideal beauty and the graceful way in which she moves , features typical of the high renaissance . this is the first time that an italian renaissance artist has completely abandoned halos . fra filippo lippi reduced the halo to a narrow ring around mary 's head .
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marriage of the virgin reflects italian high renaissance beliefs ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea .
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is there a reason why flourine ca n't be used in place of oxygen as the final acceptor in the electron transport chain ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name .
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would balsamic vinegar be an example of lactic acid fermentation since the grape bypasses the alcohol ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde .
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why plants can not regenerate pyruvate from ethanol ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ .
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can the products produced by anaerobic respiration harm the organism over time ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process .
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what enzymes are used in nad+ regeneration in alcoholic fermentation ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ .
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what are the similarities and differences in aerobic and anaerobic respiration in terms of energy transferred/ atp produced ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine .
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my understanding is that in a purely methanogenic system , you will see the following reaction pair : ch2o+2h2o- > co2+8h+ + 8e 8h+ + 8e- - > ch4+2h2o where are the protons and electrons coming from in the first step ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name .
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what happens during alcohol and lactic acid fermentation ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run .
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and what gets oxidized and why is that crucial for glycolysis ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen .
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does the amount of yeast added affect the abv percentage ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ .
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can someone explain clearly why anaerobic respiration is 2.5 times faster than aerobic respiration ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process .
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fermentation is sub-oxic process yes or no ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run .
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why is aerobic respiration more energy efficient ( producing more atp ) than glycolysis/fermentation ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end .
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why are fermentation and anaerobic production of atp by muscle cells less efficient than glycolysis ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process .
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in fermentation the temperature ranges are different , but in some alcohol fermentation the temp is maximum ( 20-25 ) celsius but after this range what will happen to the mixture ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end .
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thirdly what could happen to the reaction if not maintained a 25 celsius ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen .
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which sugar do the yeast utilize best ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process .
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if lactic fermentation is a more efficient way of getting the electron out of nadh ( because lactate can be transformed back to pyruvate and reused ) then why ca n't plants and fungi do the same , instead of doing alcohol fermentation which would eventually kill themselves ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name .
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what 's the difference between lactic acid fermentation and lactose fermentation ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process .
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can someone please explain what lactose fermentation is ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ .
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if cellular respiration is more efficient why do animals have the lactic acid metabolic pathway ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process .
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what is the primary goal of alcohol fermentation ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ .
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can bacteria undergo aerobic respiration even though they lack mitochondria ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process .
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which product of fermentation is the most important ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process .
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does alcohol fermentation happen when it is exposed to oxygen ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end .
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do plant cells undergo any form of fermentation in the absence of oxygen ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration .
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the article states that recent research suggests that soreness is not caused by the accumulation of lactate ; then what is the actual cause of the soreness and cramps in muscles after rigorous exercise ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ .
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if an organism is capable of both anaerobic respiration and fermentation and everything needed is equally available , which would it perform ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process .
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which process creates more energy , aerobic or fermentation ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process .
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what is the principle of b.subtilis fermentation ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ .
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does anyone know any good resources on anaerobic respiration using different electron acceptors ?
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introduction ever wonder how yeast ferment barley malt into beer ? or how your muscles keep working when you 're exercising so hard that they 're very low on oxygen ? both of these processes can happen thanks to alternative glucose breakdown pathways that occur when normal , oxygen-using ( aerobic ) cellular respiration is not possible—that is , when oxygen is n't around to act as an acceptor at the end of the electron transport chain . these fermentation pathways consist of glycolysis with some extra reactions tacked on at the end . in yeast , the extra reactions make alcohol , while in your muscles , they make lactic acid . fermentation is a widespread pathway , but it is not the only way to get energy from fuels anaerobically ( in the absence of oxygen ) . some living systems instead use an inorganic molecule other than $ \text { o } _2 $ , such as sulfate , as a final electron acceptor for an electron transport chain . this process , called anaerobic cellular respiration , is performed by some bacteria and archaea . in this article , we 'll take a closer look at anaerobic cellular respiration and at the different types of fermentation . anaerobic cellular respiration anaerobic cellular respiration is similar to aerobic cellular respiration in that electrons extracted from a fuel molecule are passed through an electron transport chain , driving $ \text { atp } $ synthesis . some organisms use sulfate $ ( \text { so } 4^ { 3- } ) $ as the final electron acceptor at the end ot the transport chain , while others use nitrate $ ( \text { no } { 3 } ^- ) $ , sulfur , or one of a variety of other molecules $ ^1 $ . what kinds of organisms use anaerobic cellular respiration ? some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels . for example , some archaea called methanogens can use carbon dioxide as a terminal electron acceptor , producing methane as a by-product . methanogens are found in soil and in the digestive systems of ruminants , a group of animals including cows and sheep . similarly , sulfate-reducing bacteria and archaea use sulfate as a terminal electron acceptor , producing hydrogen sulfide $ ( \text h_2\text s ) $ as a byproduct . the image below is an aerial photograph of coastal waters , and the green patches indicate an overgrowth of sulfate-reducing bacteria . fermentation fermentation is another anaerobic ( non-oxygen-requiring ) pathway for breaking down glucose , one that 's performed by many types of organisms and cells . in fermentation , the only energy extraction pathway is glycolysis , with one or two extra reactions tacked on at the end . fermentation and cellular respiration begin the same way , with glycolysis . in fermentation , however , the pyruvate made in glycolysis does not continue through oxidation and the citric acid cycle , and the electron transport chain does not run . because the electron transport chain is n't functional , the $ \text { nadh } $ made in glycolysis can not drop its electrons off there to turn back into $ \text { nad } ^+ $ the purpose of the extra reactions in fermentation , then , is to regenerate the electron carrier $ \text { nad } ^+ $ from the $ \text { nadh } $ produced in glycolysis . the extra reactions accomplish this by letting $ \text { nadh } $ drop its electrons off with an organic molecule ( such as pyruvate , the end product of glycolysis ) . this drop-off allows glycolysis to keep running by ensuring a steady supply of $ \text { nad } ^+ $ . lactic acid fermentation in lactic acid fermentation , $ \text { nadh } $ transfers its electrons directly to pyruvate , generating lactate as a byproduct . lactate , which is just the deprotonated form of lactic acid , gives the process its name . the bacteria that make yogurt carry out lactic acid fermentation , as do the red blood cells in your body , which don ’ t have mitochondria and thus can ’ t perform cellular respiration . muscle cells also carry out lactic acid fermentation , though only when they have too little oxygen for aerobic respiration to continue—for instance , when you ’ ve been exercising very hard . it was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise , but recent research suggests this is probably not the case . lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process . in the first step , a carboxyl group is removed from pyruvate and released in as carbon dioxide , producing a two-carbon molecule called acetaldehyde . in the second step , $ \text { nadh } $ passes its electrons to acetaldehyde , regenerating $ \text { nad } ^+ $ and forming ethanol . alcohol fermentation by yeast produces the ethanol found in alcoholic drinks like beer and wine . however , alcohol is toxic to yeasts in large quantities ( just as it is to humans ) , which puts an upper limit on the percentage alcohol in these drinks . ethanol tolerance of yeast ranges from about $ 5 $ percent to $ 21 $ percent , depending on the yeast strain and environmental conditions . facultative and obligate anaerobes many bacteria and archaea are facultative anaerobes , meaning they can switch between aerobic respiration and anaerobic pathways ( fermentation or anaerobic respiration ) depending on the availability of oxygen . this approach allows lets them get more atp out of their glucose molecules when oxygen is around—since aerobic cellular respiration makes more atp than anaerobic pathways—but to keep metabolizing and stay alive when oxygen is scarce . other bacteria and archaea are obligate anaerobes , meaning they can live and grow only in the absence of oxygen . oxygen is toxic to these microorganisms and injures or kills them on exposure . for instance , the clostridium bacteria that are responsible for botulism ( a form of food poisoning ) are obligate anaerobes $ ^2 $ . recently , some multicellular animals have even been discovered in deep-sea sediments that are free of oxygen $ ^ { 3,4 } $ . self-check inside these tanks , yeasts are busily fermenting grape juice into wine . why do winemaking tanks like these need pressure-release valves ?
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lactic acid produced in muscle cells is transported through the bloodstream to the liver , where it ’ s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration . alcohol fermentation another familiar fermentation process is alcohol fermentation , in which $ \text { nadh } $ donates its electrons to a derivative of pyruvate , producing ethanol . going from pyruvate to ethanol is a two-step process .
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when will fermentation stop releasing co2 ?
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overview the late roman empire led big farms to convert themselves into self-sufficient estates , due to a trade crisis and labor shortage . tenant farmer status became hereditary , as the result of changes in roman labor law that tried to freeze existing social structures in place . as the western roman empire collapsed , landholders gradually transitioned from outright slavery to serfdom , a system in which unfree laborers were tied to the land . in the absence of powerful regional authorities after the collapse of the carolingian empire in 888 , local manorial lords held sway in western europe , collecting rents and labor from unfree serfs and tenant farmers . what is feudalism ? let 's imagine that you 're a poor european farmer in the middle ages . here 's the political situation : you do n't own the land you live on . it 's rented from a baron or a duke . you and your neighbors share a plow between you , and you combine your oxen into teams to till the soil together . there 's not much social mobility : your parents and grandparents before you worked this same land . you do n't even have the legal right to leave the property , without the permission of your landlord . you 're a serf , in a feudal economy . the term feudal is a tricky one , because few scholars can quite agree on what it means these days . seventeenth-century historians and lawyers who studied the middle ages decided to give a common name to the diverse landowner-tenant arrangements that existed in northwest europe during the middle ages , starting with the collapse of charlemagne 's empire in the late ninth century and declining after the black plague and the peasant revolt in the fourteenth century . though these arrangements could range widely in style , they were lumped together under the label of feudalism , from the medieval latin term feudum referring to a landed estate . medieval economies were largely based around the operations of those landed estates . modern historians dispute whether or not it 's useful to lump together the management of these estates in that way . rather than diving into the arguments of how to organize this history , let 's discuss some common threads about those estates . for our purposes , the important thing is that those lands were cultivated with a combination of free and unfree labor—let 's talk about how that came to be . the closest europe came to operating under one system of landowner agreements was in the late eighth and early ninth century ce . charlemagne established counties and appointed counts to rule regions of his domain . but , in the wake of his death , his empire dissolved . counts who had received lands from the court of charlemagne began to consolidate their own local power , exerting control over the people who lived on their lands . they owed allegiance to the church and to the kingdoms that guaranteed their claims of land ownership , but each medieval lord established their own particular set of rules . if you were to travel through early medieval europe , you would find yourself in a hundred petty kingdoms , each with its own manor or landed estate , each one with its manorial court . the land of these manors was tilled by unfree agricultural workers , or serfs . to discover exactly what a serf is , we 'll need to move back in history a bit and visit late imperial rome . the origins of serfdom in rome slavery was foundational to the roman economy : enslaved people tilled the fields , cleaned homes , quarried—extracted—rocks and salt , and sometimes served as accountants for wealthy romans . enormous estates grew valuable crops like olives and grapes ; these estates required many enslaved people to run . the nearly fifty-year imperial crisis in the third century ce led to civil war , economic collapse , and a breakdown of trade across the roman empire . this meant a temporary end to long-distance trade of wine and olive oil . as imperial expansion slowed , fewer prisoners of war and kidnapped children were enslaved , and the elites who ran estate farms had to search elsewhere for low-cost labor . without a centralized economy to lean on , the estates had to become self-sufficient , producing food and crafts without outside aid . as city economies crumbled , lower-class plebeians from the city immigrated to the countryside and entered into a new kind of labor agreement with the landholders . neither entirely enslaved nor truly free , these former city-dwellers were called coloni . coloni were sharecropper farmers . they didn ’ t own their land ; they rented it from a landowner in exchange for a portion of the harvest produced in their fields . as this labor system emerged , roman emperors created laws that bound the coloni to the land and made their status hereditary—it passed from parent to child . coloni could marry , but they could n't marry non-coloni . they could not leave the land to which they were assigned . they could not file suit against their landlords . this system , and these restrictions , would eventually become known as serfdom . similar systems emerged independently throughout several different societies . what factors led to roman plebeians moving from the city to the countryside ? slavery and serfdom there are important distinctions between slavery and serfdom . slavery describes a system in which a person can be bought and sold as property ; enslaved people were not considered human beings with rights . take a look at a translation of this early medieval law from bavaria , a region now part of germany : “ a sale once completed should not be altered , unless a defect is found which the vendor has concealed , in the slave or horse or any other livestock sold ... : for animals have defects which a vendor can sometimes conceal. ” classifying enslaved people as livestock was typical at the time this law was written ; enslaved people were not deemed to be people . serfs , however , were legally people—though they had far fewer rights than free peasants ( poor farmers of low social status ) . serfs ' movements were constrained , their property rights were limited , and they owed rents of all sorts to their landlords . serfdom in western europe as germanic peoples overtook the western roman empire in the fifth century and beyond , many imperial institutions began to crumble . competing powers and interests destroyed traditional trade routes between parts of the roman empire . elites , whether through skill in combat or other political power , controlled the land and the people who lived on it . the roman estate farms did not disappear , but the land changed hands and purposes . landowners switched from growing grapes and olives for export to producing grain and animals for survival . like the roman coloni before them , medieval peasants or serfs could own property and marry , but there were restrictions on their rights . under a rule known as merchet or formariage , a serf had to pay a fee in order to marry outside their lord 's domain , as they were depriving him of a labor source by leaving . `` if [ a serf ] died childless '' , writes historian barbara tuchman , `` his house , tools , and any possessions reverted to the lord under the right of morte-main [ from dead hands ] , on theory that they had only been lent to the serf for his labor in life . '' although serfs could technically own property , what were some restrictions on this rule ? tenant farmers—that is , people who did n't own the land they worked—owed some kind of payment to their landlords . this could be a portion of the harvest , days of labor in the lord 's own fields—called the demesne—or money . the amount and type of payment was not influenced by market forces ; it was coercive , or forced . there was no standard rent in the middle ages , and tenant farmers had few ways to contest the rent demanded of them . the lord of the manor—who set the terms of the rent agreement—was also usually the local legal authority . a moral economy—where cultural or political intervention limits market prices or freedom of contract—was enforced by the teachings of the church . this system ensured that the lord had the right to rule and that the poor farmers were entitled to his protection . prices were established by a sense of what was just . there were , for example , biblical prohibitions against charging interest that were enforced during this period . when the shared values of the community were broken , the peasants rejected the system and revolted . as will durant writes in the story of civilization , `` the community itself was therefore the chief source of law . the baron or king might give commands , but these were not laws ; and if he exacted more than custom sanctioned he would be frustrated by universal resistance . '' lords of the manor were not always nobility . many estates in england were monasteries , for example . in an accounting from a thirteenth-century english abbey , a serf named hugh miller paid three kinds of rent : monetary , labor , and rent in the form of food . each year , miller paid three shillings and a penny—approximately \ $ 266 today . he worked the abbot 's land three days a week , except for one week at christmas , one at easter , and one at a summer festival . in addition to money and labor , miller owed the abbot one bushel of wheat , 18 sheaves of oats , three hens , and a rooster each year , with an additional five eggs owed for easter . why serfdom ? given all this , what benefit was there in serfdom ? why would a serf tolerate these practices ? without the peace guaranteed by charlemagne 's unified rule , the serfs needed a lord 's protection . in the absence of a strong centralized government , the threat of violence lurked everywhere : from bandits and the armed bands of other warlords . in exchange for tending a lord 's demesne , a serf could expect the lord 's private army to protect them . the lords needed the serfs , too ; labor shortages caused by war and disease limited the available workforce in western europe . this is part of why the terms of serfdom constrained a peasant 's rights to resettle—it maintained a labor pool for the lordly class . while the terms of these agreements could vary widely , as they were derived from a variety of sources— '' barbarian '' codes of the germanic kingdoms , church law , and roman property ordinances—some labor practices were relatively standard . the unfree farming that elite landlords oversaw sustained the military units that protected their estates , and the people who worked and lived on them . the wealth generated by these feudal estates powered the crusades , and , following the black death and the peasant revolt , would begin to concentrate in the peasant class . this would lead to artisan specialization , the growth of cities , and a desire for goods from far-off places . those factors together would lead to the rise of guild economies , the renaissance , and the colonial voyages of discovery . what was the relationship between serfs and lords , broadly ? why did lords need serfs ?
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those factors together would lead to the rise of guild economies , the renaissance , and the colonial voyages of discovery . what was the relationship between serfs and lords , broadly ? why did lords need serfs ?
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was all serfs black as in the slaves in the 1960s ?
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overview the late roman empire led big farms to convert themselves into self-sufficient estates , due to a trade crisis and labor shortage . tenant farmer status became hereditary , as the result of changes in roman labor law that tried to freeze existing social structures in place . as the western roman empire collapsed , landholders gradually transitioned from outright slavery to serfdom , a system in which unfree laborers were tied to the land . in the absence of powerful regional authorities after the collapse of the carolingian empire in 888 , local manorial lords held sway in western europe , collecting rents and labor from unfree serfs and tenant farmers . what is feudalism ? let 's imagine that you 're a poor european farmer in the middle ages . here 's the political situation : you do n't own the land you live on . it 's rented from a baron or a duke . you and your neighbors share a plow between you , and you combine your oxen into teams to till the soil together . there 's not much social mobility : your parents and grandparents before you worked this same land . you do n't even have the legal right to leave the property , without the permission of your landlord . you 're a serf , in a feudal economy . the term feudal is a tricky one , because few scholars can quite agree on what it means these days . seventeenth-century historians and lawyers who studied the middle ages decided to give a common name to the diverse landowner-tenant arrangements that existed in northwest europe during the middle ages , starting with the collapse of charlemagne 's empire in the late ninth century and declining after the black plague and the peasant revolt in the fourteenth century . though these arrangements could range widely in style , they were lumped together under the label of feudalism , from the medieval latin term feudum referring to a landed estate . medieval economies were largely based around the operations of those landed estates . modern historians dispute whether or not it 's useful to lump together the management of these estates in that way . rather than diving into the arguments of how to organize this history , let 's discuss some common threads about those estates . for our purposes , the important thing is that those lands were cultivated with a combination of free and unfree labor—let 's talk about how that came to be . the closest europe came to operating under one system of landowner agreements was in the late eighth and early ninth century ce . charlemagne established counties and appointed counts to rule regions of his domain . but , in the wake of his death , his empire dissolved . counts who had received lands from the court of charlemagne began to consolidate their own local power , exerting control over the people who lived on their lands . they owed allegiance to the church and to the kingdoms that guaranteed their claims of land ownership , but each medieval lord established their own particular set of rules . if you were to travel through early medieval europe , you would find yourself in a hundred petty kingdoms , each with its own manor or landed estate , each one with its manorial court . the land of these manors was tilled by unfree agricultural workers , or serfs . to discover exactly what a serf is , we 'll need to move back in history a bit and visit late imperial rome . the origins of serfdom in rome slavery was foundational to the roman economy : enslaved people tilled the fields , cleaned homes , quarried—extracted—rocks and salt , and sometimes served as accountants for wealthy romans . enormous estates grew valuable crops like olives and grapes ; these estates required many enslaved people to run . the nearly fifty-year imperial crisis in the third century ce led to civil war , economic collapse , and a breakdown of trade across the roman empire . this meant a temporary end to long-distance trade of wine and olive oil . as imperial expansion slowed , fewer prisoners of war and kidnapped children were enslaved , and the elites who ran estate farms had to search elsewhere for low-cost labor . without a centralized economy to lean on , the estates had to become self-sufficient , producing food and crafts without outside aid . as city economies crumbled , lower-class plebeians from the city immigrated to the countryside and entered into a new kind of labor agreement with the landholders . neither entirely enslaved nor truly free , these former city-dwellers were called coloni . coloni were sharecropper farmers . they didn ’ t own their land ; they rented it from a landowner in exchange for a portion of the harvest produced in their fields . as this labor system emerged , roman emperors created laws that bound the coloni to the land and made their status hereditary—it passed from parent to child . coloni could marry , but they could n't marry non-coloni . they could not leave the land to which they were assigned . they could not file suit against their landlords . this system , and these restrictions , would eventually become known as serfdom . similar systems emerged independently throughout several different societies . what factors led to roman plebeians moving from the city to the countryside ? slavery and serfdom there are important distinctions between slavery and serfdom . slavery describes a system in which a person can be bought and sold as property ; enslaved people were not considered human beings with rights . take a look at a translation of this early medieval law from bavaria , a region now part of germany : “ a sale once completed should not be altered , unless a defect is found which the vendor has concealed , in the slave or horse or any other livestock sold ... : for animals have defects which a vendor can sometimes conceal. ” classifying enslaved people as livestock was typical at the time this law was written ; enslaved people were not deemed to be people . serfs , however , were legally people—though they had far fewer rights than free peasants ( poor farmers of low social status ) . serfs ' movements were constrained , their property rights were limited , and they owed rents of all sorts to their landlords . serfdom in western europe as germanic peoples overtook the western roman empire in the fifth century and beyond , many imperial institutions began to crumble . competing powers and interests destroyed traditional trade routes between parts of the roman empire . elites , whether through skill in combat or other political power , controlled the land and the people who lived on it . the roman estate farms did not disappear , but the land changed hands and purposes . landowners switched from growing grapes and olives for export to producing grain and animals for survival . like the roman coloni before them , medieval peasants or serfs could own property and marry , but there were restrictions on their rights . under a rule known as merchet or formariage , a serf had to pay a fee in order to marry outside their lord 's domain , as they were depriving him of a labor source by leaving . `` if [ a serf ] died childless '' , writes historian barbara tuchman , `` his house , tools , and any possessions reverted to the lord under the right of morte-main [ from dead hands ] , on theory that they had only been lent to the serf for his labor in life . '' although serfs could technically own property , what were some restrictions on this rule ? tenant farmers—that is , people who did n't own the land they worked—owed some kind of payment to their landlords . this could be a portion of the harvest , days of labor in the lord 's own fields—called the demesne—or money . the amount and type of payment was not influenced by market forces ; it was coercive , or forced . there was no standard rent in the middle ages , and tenant farmers had few ways to contest the rent demanded of them . the lord of the manor—who set the terms of the rent agreement—was also usually the local legal authority . a moral economy—where cultural or political intervention limits market prices or freedom of contract—was enforced by the teachings of the church . this system ensured that the lord had the right to rule and that the poor farmers were entitled to his protection . prices were established by a sense of what was just . there were , for example , biblical prohibitions against charging interest that were enforced during this period . when the shared values of the community were broken , the peasants rejected the system and revolted . as will durant writes in the story of civilization , `` the community itself was therefore the chief source of law . the baron or king might give commands , but these were not laws ; and if he exacted more than custom sanctioned he would be frustrated by universal resistance . '' lords of the manor were not always nobility . many estates in england were monasteries , for example . in an accounting from a thirteenth-century english abbey , a serf named hugh miller paid three kinds of rent : monetary , labor , and rent in the form of food . each year , miller paid three shillings and a penny—approximately \ $ 266 today . he worked the abbot 's land three days a week , except for one week at christmas , one at easter , and one at a summer festival . in addition to money and labor , miller owed the abbot one bushel of wheat , 18 sheaves of oats , three hens , and a rooster each year , with an additional five eggs owed for easter . why serfdom ? given all this , what benefit was there in serfdom ? why would a serf tolerate these practices ? without the peace guaranteed by charlemagne 's unified rule , the serfs needed a lord 's protection . in the absence of a strong centralized government , the threat of violence lurked everywhere : from bandits and the armed bands of other warlords . in exchange for tending a lord 's demesne , a serf could expect the lord 's private army to protect them . the lords needed the serfs , too ; labor shortages caused by war and disease limited the available workforce in western europe . this is part of why the terms of serfdom constrained a peasant 's rights to resettle—it maintained a labor pool for the lordly class . while the terms of these agreements could vary widely , as they were derived from a variety of sources— '' barbarian '' codes of the germanic kingdoms , church law , and roman property ordinances—some labor practices were relatively standard . the unfree farming that elite landlords oversaw sustained the military units that protected their estates , and the people who worked and lived on them . the wealth generated by these feudal estates powered the crusades , and , following the black death and the peasant revolt , would begin to concentrate in the peasant class . this would lead to artisan specialization , the growth of cities , and a desire for goods from far-off places . those factors together would lead to the rise of guild economies , the renaissance , and the colonial voyages of discovery . what was the relationship between serfs and lords , broadly ? why did lords need serfs ?
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similar systems emerged independently throughout several different societies . what factors led to roman plebeians moving from the city to the countryside ? slavery and serfdom there are important distinctions between slavery and serfdom .
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what factors led to roman plebeians moving from the city to the countryside ?
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gian lorenzo bernini ; view to cathedra petri ( chair of st. peter ) , gilded bronze , gold , wood , stained glass ; 1647-53 ( apse of saint peter 's basilica , vatican city , rome ) . image credit : steven zucker , cc by-nc-sa 2.0 rome : from the whore of babylon to the resplendent bride of christ when martin luther tacked his 95 theses to the doors of wittenberg cathedral in 1517 protesting the catholic church ’ s corruption , he initiated a movement that would transform the religious , political , and artistic landscape of europe . for the next century , europe would be in turmoil as new political and religious boundaries were determined , often through bloody military conflicts . only in 1648 , with the signing of the treaty of westphalia , did the conflicts between protestants and catholics subside in continental europe . martin luther focused his critique on what he saw as the church ’ s greed and abuse of power . he called rome , the seat of papal power , “ the whore of babylon ” decked out in finery of expensive art , grand architecture , and sumptuous banquets . the church responded to the crisis in two ways : by internally addressing issues of corruption and by defending the doctrines rejected by the protestants . thus , while the first two decades of the 16th century were a period of lavish spending for the papacy , the middle decades were a period of austerity . as one visitor to rome noted in the 1560s , the entire city had become a convent . piety and asceticism ruled the day . by the end of the 16th century , the catholic church was once again feeling optimistic , even triumphant . it had emerged from the crisis with renewed vigor and clarity of purpose . shepherding the faithful—instructing them on catholic doctrines and inspiring virtuous behavior—took center stage . keen to rebuild rome ’ s reputation as a holy city , the papacy embarked on extensive building and decoration campaigns aimed at highlighting its ancient origins , its beliefs , and its divinely-sanctioned authority . in the eyes of faithful catholics , rome was not an unfaithful whore , but a pure bride , beautifully adorned for her union with her divine spouse . the art of persuasion : instruct , delight , move while the protestants harshly criticized the cult of images , the catholic church ardently embraced the religious power of art . the visual arts , the church argued , played a key role in guiding the faithful . they were certainly as important as the written and spoken word , and perhaps even more important since they were accessible to the learned and the unlearned alike . in order to be effective in its pastoral role , religious art had to be clear , persuasive , and powerful . not only did it have to instruct , it had to inspire . it had to move the faithful to feel the reality of christ ’ s sacrifice , the suffering of the martyrs , the visions of the saints . caravaggio , the crowning with thorns , 1602-04 , oil on canvas , 165.5 x 127 cm ( kunsthistorisches museum , vienna ) the church ’ s emphasis on art ’ s pastoral role prompted artists to experiment with new and more direct means of engaging the viewer . artists like caravaggio turned to a powerful and dramatic realism , accentuated by bold contrasts of light and dark , and tightly-cropped compositions that enhanced the physical and emotional immediacy of the depicted narrative . other artists , like annibale carracci—who also experimented with realism—ultimately settled on a more classical visual language , inspired by the vibrant palette , idealized forms , and balanced compositions of the high renaissance , see image above . still others , like giovanni battista gaulli , turned to daring feats of illusionism that blurred not only the boundaries between painting , sculpture , and architecture , but also those between the real and depicted worlds . in so doing , the divine was made physically present and palpable . whether through shocking realism , dynamic movement , or exuberant ornamentation , 17th-century art was meant to impress . it aimed to convince the viewer of the truth of its message by impacting the senses , awakening the emotions , and activating—even sharing—the viewer ’ s space . giovanni battista gaulli , also known as il baciccio , the triumph of the name of jesus , il , gesù ceiling fresco , 1672-1685 the catholic monarchs and their territories the monarchs of spain , portugal , and france also embraced the more ornate elements of 17th-century art to celebrate catholicism . in spain and its colonies , rulers invested vast resources on elaborate church facades , stunning , gold-covered chapels and tabernacles , and strikingly-realistic polychrome sculpture . in the spanish netherlands , where sacred art had suffered terribly as a result of the protestant iconoclasm—the destruction of art—civic and religious leaders prioritized the adornment of churches as the region reclaimed its catholic identity . refurnishing the altars of antwerp ’ s churches kept peter paul rubens ’ workshop busy for many years . europe ’ s monarchs also adopted this artistic vocabulary to proclaim their own power and status . louis xiv , for example , commissioned the splendid buildings and gardens of versailles as a visual expression of his divine right to rule . peter paul rubens , elevation of the cross , 1610 , oil on wood , 15 ft 1-7/8 in x 11 ft 1-1/2 in ( originally for saint walpurgis , antwerp [ destroyed ] , now in antwerp cathedral ) the protestant north in the protestant countries , and especially in the newly-independent dutch republic , modern-day holland , the artistic climate changed radically in the aftermath of the reformation . two of the wealthiest sources of patronage—the monarchy and the church—were now gone . in their stead arose an increasingly prosperous middle class eager to express its status and its new sense of national pride through the purchase of art . by the middle of the 17th century , a new market had emerged to meet the artistic tastes of this class . the demand was now for smaller-scale paintings suitable for display in private homes . these paintings included religious subjects for private contemplation , as seen in rembrandt ’ s poignant paintings and prints of biblical narratives , as well as portraits documenting individual likenesses . judith leyster , self-portrait , c. 1630 , oil on canvas , 651 x 746 cm ( national gallery of art , washington ) but , the greatest change in the market was the dramatic increase in the popularity of landscapes , still-lifes , and scenes of everyday life—known as genre painting . indeed , the proliferation of these subjects as independent artistic genres was one of the 17th century ’ s most significant contributions to the history of western art . in all of these genres , artists revealed a keen interest in replicating observed reality—whether it be the light on the dutch landscape , the momentary expression on a face , or the varied textures and materials of the objects the dutch collected as they reaped the benefits of their expanding mercantile empire . these works demonstrated as much artistic virtuosity and physical immediacy as the grand decorations of the palaces and churches of catholic europe . in the context of european history , the period from c. 1585 to c. 1700/1730 is often called the baroque era . the word baroque derives from the portuguese and spanish words for a large , irregularly-shaped pearl—barroco and barrueco , respectively . eighteenth-century critics were the first to apply the term to the art of the 17th century . it was not a term of praise . to the eyes of these critics , who favored the restraint and order of neoclassicism , the works of bernini , borromini , and pietro da cortona appeared bizarre , absurd , even diseased—in other words , misshapen , like an imperfect pearl . francisco de zurbarán , saint francis of assisi according to pope nicholas v 's vision , c. 1640 , oil on canvas , 110.5 x 180.5 cm ( museum nacional d'art de catalunya , barcelona ) baroque—the word , the style , the period by the middle of the 19th century , the word baroque had lost its pejorative implications and was used to describe the ornate and complex qualities present in many examples of 17th-century art , music , and literature . eventually , the term came to designate the historical period as a whole . in the context of painting , for example , the stark realism of zurbaran ’ s altarpieces , the quiet intimacy of vermeer ’ s domestic interiors , and the restrained classicism of poussin ’ s landscapes are all baroque—now with a capital b to indicate the historical period—regardless of the absence of the stylistic traits originally associated with the term . scholars continue to debate the validity of this label , admitting the usefulness of having a label for this distinct historical period , while also acknowledging its limitations in characterizing the variety of artistic styles present in the 17th century . essay by dr. esperança camara additional resources baroque rome on the metropolitan museum of art 's heilbrunn timeline of art history annibale carracci on the metropolitan museum of art 's heilbrunn timeline of art history
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scholars continue to debate the validity of this label , admitting the usefulness of having a label for this distinct historical period , while also acknowledging its limitations in characterizing the variety of artistic styles present in the 17th century . essay by dr. esperança camara additional resources baroque rome on the metropolitan museum of art 's heilbrunn timeline of art history annibale carracci on the metropolitan museum of art 's heilbrunn timeline of art history
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where any more pieces of art that were leaning towards protestantism ?
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gian lorenzo bernini ; view to cathedra petri ( chair of st. peter ) , gilded bronze , gold , wood , stained glass ; 1647-53 ( apse of saint peter 's basilica , vatican city , rome ) . image credit : steven zucker , cc by-nc-sa 2.0 rome : from the whore of babylon to the resplendent bride of christ when martin luther tacked his 95 theses to the doors of wittenberg cathedral in 1517 protesting the catholic church ’ s corruption , he initiated a movement that would transform the religious , political , and artistic landscape of europe . for the next century , europe would be in turmoil as new political and religious boundaries were determined , often through bloody military conflicts . only in 1648 , with the signing of the treaty of westphalia , did the conflicts between protestants and catholics subside in continental europe . martin luther focused his critique on what he saw as the church ’ s greed and abuse of power . he called rome , the seat of papal power , “ the whore of babylon ” decked out in finery of expensive art , grand architecture , and sumptuous banquets . the church responded to the crisis in two ways : by internally addressing issues of corruption and by defending the doctrines rejected by the protestants . thus , while the first two decades of the 16th century were a period of lavish spending for the papacy , the middle decades were a period of austerity . as one visitor to rome noted in the 1560s , the entire city had become a convent . piety and asceticism ruled the day . by the end of the 16th century , the catholic church was once again feeling optimistic , even triumphant . it had emerged from the crisis with renewed vigor and clarity of purpose . shepherding the faithful—instructing them on catholic doctrines and inspiring virtuous behavior—took center stage . keen to rebuild rome ’ s reputation as a holy city , the papacy embarked on extensive building and decoration campaigns aimed at highlighting its ancient origins , its beliefs , and its divinely-sanctioned authority . in the eyes of faithful catholics , rome was not an unfaithful whore , but a pure bride , beautifully adorned for her union with her divine spouse . the art of persuasion : instruct , delight , move while the protestants harshly criticized the cult of images , the catholic church ardently embraced the religious power of art . the visual arts , the church argued , played a key role in guiding the faithful . they were certainly as important as the written and spoken word , and perhaps even more important since they were accessible to the learned and the unlearned alike . in order to be effective in its pastoral role , religious art had to be clear , persuasive , and powerful . not only did it have to instruct , it had to inspire . it had to move the faithful to feel the reality of christ ’ s sacrifice , the suffering of the martyrs , the visions of the saints . caravaggio , the crowning with thorns , 1602-04 , oil on canvas , 165.5 x 127 cm ( kunsthistorisches museum , vienna ) the church ’ s emphasis on art ’ s pastoral role prompted artists to experiment with new and more direct means of engaging the viewer . artists like caravaggio turned to a powerful and dramatic realism , accentuated by bold contrasts of light and dark , and tightly-cropped compositions that enhanced the physical and emotional immediacy of the depicted narrative . other artists , like annibale carracci—who also experimented with realism—ultimately settled on a more classical visual language , inspired by the vibrant palette , idealized forms , and balanced compositions of the high renaissance , see image above . still others , like giovanni battista gaulli , turned to daring feats of illusionism that blurred not only the boundaries between painting , sculpture , and architecture , but also those between the real and depicted worlds . in so doing , the divine was made physically present and palpable . whether through shocking realism , dynamic movement , or exuberant ornamentation , 17th-century art was meant to impress . it aimed to convince the viewer of the truth of its message by impacting the senses , awakening the emotions , and activating—even sharing—the viewer ’ s space . giovanni battista gaulli , also known as il baciccio , the triumph of the name of jesus , il , gesù ceiling fresco , 1672-1685 the catholic monarchs and their territories the monarchs of spain , portugal , and france also embraced the more ornate elements of 17th-century art to celebrate catholicism . in spain and its colonies , rulers invested vast resources on elaborate church facades , stunning , gold-covered chapels and tabernacles , and strikingly-realistic polychrome sculpture . in the spanish netherlands , where sacred art had suffered terribly as a result of the protestant iconoclasm—the destruction of art—civic and religious leaders prioritized the adornment of churches as the region reclaimed its catholic identity . refurnishing the altars of antwerp ’ s churches kept peter paul rubens ’ workshop busy for many years . europe ’ s monarchs also adopted this artistic vocabulary to proclaim their own power and status . louis xiv , for example , commissioned the splendid buildings and gardens of versailles as a visual expression of his divine right to rule . peter paul rubens , elevation of the cross , 1610 , oil on wood , 15 ft 1-7/8 in x 11 ft 1-1/2 in ( originally for saint walpurgis , antwerp [ destroyed ] , now in antwerp cathedral ) the protestant north in the protestant countries , and especially in the newly-independent dutch republic , modern-day holland , the artistic climate changed radically in the aftermath of the reformation . two of the wealthiest sources of patronage—the monarchy and the church—were now gone . in their stead arose an increasingly prosperous middle class eager to express its status and its new sense of national pride through the purchase of art . by the middle of the 17th century , a new market had emerged to meet the artistic tastes of this class . the demand was now for smaller-scale paintings suitable for display in private homes . these paintings included religious subjects for private contemplation , as seen in rembrandt ’ s poignant paintings and prints of biblical narratives , as well as portraits documenting individual likenesses . judith leyster , self-portrait , c. 1630 , oil on canvas , 651 x 746 cm ( national gallery of art , washington ) but , the greatest change in the market was the dramatic increase in the popularity of landscapes , still-lifes , and scenes of everyday life—known as genre painting . indeed , the proliferation of these subjects as independent artistic genres was one of the 17th century ’ s most significant contributions to the history of western art . in all of these genres , artists revealed a keen interest in replicating observed reality—whether it be the light on the dutch landscape , the momentary expression on a face , or the varied textures and materials of the objects the dutch collected as they reaped the benefits of their expanding mercantile empire . these works demonstrated as much artistic virtuosity and physical immediacy as the grand decorations of the palaces and churches of catholic europe . in the context of european history , the period from c. 1585 to c. 1700/1730 is often called the baroque era . the word baroque derives from the portuguese and spanish words for a large , irregularly-shaped pearl—barroco and barrueco , respectively . eighteenth-century critics were the first to apply the term to the art of the 17th century . it was not a term of praise . to the eyes of these critics , who favored the restraint and order of neoclassicism , the works of bernini , borromini , and pietro da cortona appeared bizarre , absurd , even diseased—in other words , misshapen , like an imperfect pearl . francisco de zurbarán , saint francis of assisi according to pope nicholas v 's vision , c. 1640 , oil on canvas , 110.5 x 180.5 cm ( museum nacional d'art de catalunya , barcelona ) baroque—the word , the style , the period by the middle of the 19th century , the word baroque had lost its pejorative implications and was used to describe the ornate and complex qualities present in many examples of 17th-century art , music , and literature . eventually , the term came to designate the historical period as a whole . in the context of painting , for example , the stark realism of zurbaran ’ s altarpieces , the quiet intimacy of vermeer ’ s domestic interiors , and the restrained classicism of poussin ’ s landscapes are all baroque—now with a capital b to indicate the historical period—regardless of the absence of the stylistic traits originally associated with the term . scholars continue to debate the validity of this label , admitting the usefulness of having a label for this distinct historical period , while also acknowledging its limitations in characterizing the variety of artistic styles present in the 17th century . essay by dr. esperança camara additional resources baroque rome on the metropolitan museum of art 's heilbrunn timeline of art history annibale carracci on the metropolitan museum of art 's heilbrunn timeline of art history
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scholars continue to debate the validity of this label , admitting the usefulness of having a label for this distinct historical period , while also acknowledging its limitations in characterizing the variety of artistic styles present in the 17th century . essay by dr. esperança camara additional resources baroque rome on the metropolitan museum of art 's heilbrunn timeline of art history annibale carracci on the metropolitan museum of art 's heilbrunn timeline of art history
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did the baroque era of painting have any significantly different technical styles ( paintingwise ) from the art of the renaissance ?
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gian lorenzo bernini ; view to cathedra petri ( chair of st. peter ) , gilded bronze , gold , wood , stained glass ; 1647-53 ( apse of saint peter 's basilica , vatican city , rome ) . image credit : steven zucker , cc by-nc-sa 2.0 rome : from the whore of babylon to the resplendent bride of christ when martin luther tacked his 95 theses to the doors of wittenberg cathedral in 1517 protesting the catholic church ’ s corruption , he initiated a movement that would transform the religious , political , and artistic landscape of europe . for the next century , europe would be in turmoil as new political and religious boundaries were determined , often through bloody military conflicts . only in 1648 , with the signing of the treaty of westphalia , did the conflicts between protestants and catholics subside in continental europe . martin luther focused his critique on what he saw as the church ’ s greed and abuse of power . he called rome , the seat of papal power , “ the whore of babylon ” decked out in finery of expensive art , grand architecture , and sumptuous banquets . the church responded to the crisis in two ways : by internally addressing issues of corruption and by defending the doctrines rejected by the protestants . thus , while the first two decades of the 16th century were a period of lavish spending for the papacy , the middle decades were a period of austerity . as one visitor to rome noted in the 1560s , the entire city had become a convent . piety and asceticism ruled the day . by the end of the 16th century , the catholic church was once again feeling optimistic , even triumphant . it had emerged from the crisis with renewed vigor and clarity of purpose . shepherding the faithful—instructing them on catholic doctrines and inspiring virtuous behavior—took center stage . keen to rebuild rome ’ s reputation as a holy city , the papacy embarked on extensive building and decoration campaigns aimed at highlighting its ancient origins , its beliefs , and its divinely-sanctioned authority . in the eyes of faithful catholics , rome was not an unfaithful whore , but a pure bride , beautifully adorned for her union with her divine spouse . the art of persuasion : instruct , delight , move while the protestants harshly criticized the cult of images , the catholic church ardently embraced the religious power of art . the visual arts , the church argued , played a key role in guiding the faithful . they were certainly as important as the written and spoken word , and perhaps even more important since they were accessible to the learned and the unlearned alike . in order to be effective in its pastoral role , religious art had to be clear , persuasive , and powerful . not only did it have to instruct , it had to inspire . it had to move the faithful to feel the reality of christ ’ s sacrifice , the suffering of the martyrs , the visions of the saints . caravaggio , the crowning with thorns , 1602-04 , oil on canvas , 165.5 x 127 cm ( kunsthistorisches museum , vienna ) the church ’ s emphasis on art ’ s pastoral role prompted artists to experiment with new and more direct means of engaging the viewer . artists like caravaggio turned to a powerful and dramatic realism , accentuated by bold contrasts of light and dark , and tightly-cropped compositions that enhanced the physical and emotional immediacy of the depicted narrative . other artists , like annibale carracci—who also experimented with realism—ultimately settled on a more classical visual language , inspired by the vibrant palette , idealized forms , and balanced compositions of the high renaissance , see image above . still others , like giovanni battista gaulli , turned to daring feats of illusionism that blurred not only the boundaries between painting , sculpture , and architecture , but also those between the real and depicted worlds . in so doing , the divine was made physically present and palpable . whether through shocking realism , dynamic movement , or exuberant ornamentation , 17th-century art was meant to impress . it aimed to convince the viewer of the truth of its message by impacting the senses , awakening the emotions , and activating—even sharing—the viewer ’ s space . giovanni battista gaulli , also known as il baciccio , the triumph of the name of jesus , il , gesù ceiling fresco , 1672-1685 the catholic monarchs and their territories the monarchs of spain , portugal , and france also embraced the more ornate elements of 17th-century art to celebrate catholicism . in spain and its colonies , rulers invested vast resources on elaborate church facades , stunning , gold-covered chapels and tabernacles , and strikingly-realistic polychrome sculpture . in the spanish netherlands , where sacred art had suffered terribly as a result of the protestant iconoclasm—the destruction of art—civic and religious leaders prioritized the adornment of churches as the region reclaimed its catholic identity . refurnishing the altars of antwerp ’ s churches kept peter paul rubens ’ workshop busy for many years . europe ’ s monarchs also adopted this artistic vocabulary to proclaim their own power and status . louis xiv , for example , commissioned the splendid buildings and gardens of versailles as a visual expression of his divine right to rule . peter paul rubens , elevation of the cross , 1610 , oil on wood , 15 ft 1-7/8 in x 11 ft 1-1/2 in ( originally for saint walpurgis , antwerp [ destroyed ] , now in antwerp cathedral ) the protestant north in the protestant countries , and especially in the newly-independent dutch republic , modern-day holland , the artistic climate changed radically in the aftermath of the reformation . two of the wealthiest sources of patronage—the monarchy and the church—were now gone . in their stead arose an increasingly prosperous middle class eager to express its status and its new sense of national pride through the purchase of art . by the middle of the 17th century , a new market had emerged to meet the artistic tastes of this class . the demand was now for smaller-scale paintings suitable for display in private homes . these paintings included religious subjects for private contemplation , as seen in rembrandt ’ s poignant paintings and prints of biblical narratives , as well as portraits documenting individual likenesses . judith leyster , self-portrait , c. 1630 , oil on canvas , 651 x 746 cm ( national gallery of art , washington ) but , the greatest change in the market was the dramatic increase in the popularity of landscapes , still-lifes , and scenes of everyday life—known as genre painting . indeed , the proliferation of these subjects as independent artistic genres was one of the 17th century ’ s most significant contributions to the history of western art . in all of these genres , artists revealed a keen interest in replicating observed reality—whether it be the light on the dutch landscape , the momentary expression on a face , or the varied textures and materials of the objects the dutch collected as they reaped the benefits of their expanding mercantile empire . these works demonstrated as much artistic virtuosity and physical immediacy as the grand decorations of the palaces and churches of catholic europe . in the context of european history , the period from c. 1585 to c. 1700/1730 is often called the baroque era . the word baroque derives from the portuguese and spanish words for a large , irregularly-shaped pearl—barroco and barrueco , respectively . eighteenth-century critics were the first to apply the term to the art of the 17th century . it was not a term of praise . to the eyes of these critics , who favored the restraint and order of neoclassicism , the works of bernini , borromini , and pietro da cortona appeared bizarre , absurd , even diseased—in other words , misshapen , like an imperfect pearl . francisco de zurbarán , saint francis of assisi according to pope nicholas v 's vision , c. 1640 , oil on canvas , 110.5 x 180.5 cm ( museum nacional d'art de catalunya , barcelona ) baroque—the word , the style , the period by the middle of the 19th century , the word baroque had lost its pejorative implications and was used to describe the ornate and complex qualities present in many examples of 17th-century art , music , and literature . eventually , the term came to designate the historical period as a whole . in the context of painting , for example , the stark realism of zurbaran ’ s altarpieces , the quiet intimacy of vermeer ’ s domestic interiors , and the restrained classicism of poussin ’ s landscapes are all baroque—now with a capital b to indicate the historical period—regardless of the absence of the stylistic traits originally associated with the term . scholars continue to debate the validity of this label , admitting the usefulness of having a label for this distinct historical period , while also acknowledging its limitations in characterizing the variety of artistic styles present in the 17th century . essay by dr. esperança camara additional resources baroque rome on the metropolitan museum of art 's heilbrunn timeline of art history annibale carracci on the metropolitan museum of art 's heilbrunn timeline of art history
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europe ’ s monarchs also adopted this artistic vocabulary to proclaim their own power and status . louis xiv , for example , commissioned the splendid buildings and gardens of versailles as a visual expression of his divine right to rule . peter paul rubens , elevation of the cross , 1610 , oil on wood , 15 ft 1-7/8 in x 11 ft 1-1/2 in ( originally for saint walpurgis , antwerp [ destroyed ] , now in antwerp cathedral ) the protestant north in the protestant countries , and especially in the newly-independent dutch republic , modern-day holland , the artistic climate changed radically in the aftermath of the reformation .
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aside from artists , were there other types of people working on these buildings , such as mathematicians , and architects ?
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gian lorenzo bernini ; view to cathedra petri ( chair of st. peter ) , gilded bronze , gold , wood , stained glass ; 1647-53 ( apse of saint peter 's basilica , vatican city , rome ) . image credit : steven zucker , cc by-nc-sa 2.0 rome : from the whore of babylon to the resplendent bride of christ when martin luther tacked his 95 theses to the doors of wittenberg cathedral in 1517 protesting the catholic church ’ s corruption , he initiated a movement that would transform the religious , political , and artistic landscape of europe . for the next century , europe would be in turmoil as new political and religious boundaries were determined , often through bloody military conflicts . only in 1648 , with the signing of the treaty of westphalia , did the conflicts between protestants and catholics subside in continental europe . martin luther focused his critique on what he saw as the church ’ s greed and abuse of power . he called rome , the seat of papal power , “ the whore of babylon ” decked out in finery of expensive art , grand architecture , and sumptuous banquets . the church responded to the crisis in two ways : by internally addressing issues of corruption and by defending the doctrines rejected by the protestants . thus , while the first two decades of the 16th century were a period of lavish spending for the papacy , the middle decades were a period of austerity . as one visitor to rome noted in the 1560s , the entire city had become a convent . piety and asceticism ruled the day . by the end of the 16th century , the catholic church was once again feeling optimistic , even triumphant . it had emerged from the crisis with renewed vigor and clarity of purpose . shepherding the faithful—instructing them on catholic doctrines and inspiring virtuous behavior—took center stage . keen to rebuild rome ’ s reputation as a holy city , the papacy embarked on extensive building and decoration campaigns aimed at highlighting its ancient origins , its beliefs , and its divinely-sanctioned authority . in the eyes of faithful catholics , rome was not an unfaithful whore , but a pure bride , beautifully adorned for her union with her divine spouse . the art of persuasion : instruct , delight , move while the protestants harshly criticized the cult of images , the catholic church ardently embraced the religious power of art . the visual arts , the church argued , played a key role in guiding the faithful . they were certainly as important as the written and spoken word , and perhaps even more important since they were accessible to the learned and the unlearned alike . in order to be effective in its pastoral role , religious art had to be clear , persuasive , and powerful . not only did it have to instruct , it had to inspire . it had to move the faithful to feel the reality of christ ’ s sacrifice , the suffering of the martyrs , the visions of the saints . caravaggio , the crowning with thorns , 1602-04 , oil on canvas , 165.5 x 127 cm ( kunsthistorisches museum , vienna ) the church ’ s emphasis on art ’ s pastoral role prompted artists to experiment with new and more direct means of engaging the viewer . artists like caravaggio turned to a powerful and dramatic realism , accentuated by bold contrasts of light and dark , and tightly-cropped compositions that enhanced the physical and emotional immediacy of the depicted narrative . other artists , like annibale carracci—who also experimented with realism—ultimately settled on a more classical visual language , inspired by the vibrant palette , idealized forms , and balanced compositions of the high renaissance , see image above . still others , like giovanni battista gaulli , turned to daring feats of illusionism that blurred not only the boundaries between painting , sculpture , and architecture , but also those between the real and depicted worlds . in so doing , the divine was made physically present and palpable . whether through shocking realism , dynamic movement , or exuberant ornamentation , 17th-century art was meant to impress . it aimed to convince the viewer of the truth of its message by impacting the senses , awakening the emotions , and activating—even sharing—the viewer ’ s space . giovanni battista gaulli , also known as il baciccio , the triumph of the name of jesus , il , gesù ceiling fresco , 1672-1685 the catholic monarchs and their territories the monarchs of spain , portugal , and france also embraced the more ornate elements of 17th-century art to celebrate catholicism . in spain and its colonies , rulers invested vast resources on elaborate church facades , stunning , gold-covered chapels and tabernacles , and strikingly-realistic polychrome sculpture . in the spanish netherlands , where sacred art had suffered terribly as a result of the protestant iconoclasm—the destruction of art—civic and religious leaders prioritized the adornment of churches as the region reclaimed its catholic identity . refurnishing the altars of antwerp ’ s churches kept peter paul rubens ’ workshop busy for many years . europe ’ s monarchs also adopted this artistic vocabulary to proclaim their own power and status . louis xiv , for example , commissioned the splendid buildings and gardens of versailles as a visual expression of his divine right to rule . peter paul rubens , elevation of the cross , 1610 , oil on wood , 15 ft 1-7/8 in x 11 ft 1-1/2 in ( originally for saint walpurgis , antwerp [ destroyed ] , now in antwerp cathedral ) the protestant north in the protestant countries , and especially in the newly-independent dutch republic , modern-day holland , the artistic climate changed radically in the aftermath of the reformation . two of the wealthiest sources of patronage—the monarchy and the church—were now gone . in their stead arose an increasingly prosperous middle class eager to express its status and its new sense of national pride through the purchase of art . by the middle of the 17th century , a new market had emerged to meet the artistic tastes of this class . the demand was now for smaller-scale paintings suitable for display in private homes . these paintings included religious subjects for private contemplation , as seen in rembrandt ’ s poignant paintings and prints of biblical narratives , as well as portraits documenting individual likenesses . judith leyster , self-portrait , c. 1630 , oil on canvas , 651 x 746 cm ( national gallery of art , washington ) but , the greatest change in the market was the dramatic increase in the popularity of landscapes , still-lifes , and scenes of everyday life—known as genre painting . indeed , the proliferation of these subjects as independent artistic genres was one of the 17th century ’ s most significant contributions to the history of western art . in all of these genres , artists revealed a keen interest in replicating observed reality—whether it be the light on the dutch landscape , the momentary expression on a face , or the varied textures and materials of the objects the dutch collected as they reaped the benefits of their expanding mercantile empire . these works demonstrated as much artistic virtuosity and physical immediacy as the grand decorations of the palaces and churches of catholic europe . in the context of european history , the period from c. 1585 to c. 1700/1730 is often called the baroque era . the word baroque derives from the portuguese and spanish words for a large , irregularly-shaped pearl—barroco and barrueco , respectively . eighteenth-century critics were the first to apply the term to the art of the 17th century . it was not a term of praise . to the eyes of these critics , who favored the restraint and order of neoclassicism , the works of bernini , borromini , and pietro da cortona appeared bizarre , absurd , even diseased—in other words , misshapen , like an imperfect pearl . francisco de zurbarán , saint francis of assisi according to pope nicholas v 's vision , c. 1640 , oil on canvas , 110.5 x 180.5 cm ( museum nacional d'art de catalunya , barcelona ) baroque—the word , the style , the period by the middle of the 19th century , the word baroque had lost its pejorative implications and was used to describe the ornate and complex qualities present in many examples of 17th-century art , music , and literature . eventually , the term came to designate the historical period as a whole . in the context of painting , for example , the stark realism of zurbaran ’ s altarpieces , the quiet intimacy of vermeer ’ s domestic interiors , and the restrained classicism of poussin ’ s landscapes are all baroque—now with a capital b to indicate the historical period—regardless of the absence of the stylistic traits originally associated with the term . scholars continue to debate the validity of this label , admitting the usefulness of having a label for this distinct historical period , while also acknowledging its limitations in characterizing the variety of artistic styles present in the 17th century . essay by dr. esperança camara additional resources baroque rome on the metropolitan museum of art 's heilbrunn timeline of art history annibale carracci on the metropolitan museum of art 's heilbrunn timeline of art history
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europe ’ s monarchs also adopted this artistic vocabulary to proclaim their own power and status . louis xiv , for example , commissioned the splendid buildings and gardens of versailles as a visual expression of his divine right to rule . peter paul rubens , elevation of the cross , 1610 , oil on wood , 15 ft 1-7/8 in x 11 ft 1-1/2 in ( originally for saint walpurgis , antwerp [ destroyed ] , now in antwerp cathedral ) the protestant north in the protestant countries , and especially in the newly-independent dutch republic , modern-day holland , the artistic climate changed radically in the aftermath of the reformation .
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and what cultures did the design inspiration come from for these buildings ?
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gian lorenzo bernini ; view to cathedra petri ( chair of st. peter ) , gilded bronze , gold , wood , stained glass ; 1647-53 ( apse of saint peter 's basilica , vatican city , rome ) . image credit : steven zucker , cc by-nc-sa 2.0 rome : from the whore of babylon to the resplendent bride of christ when martin luther tacked his 95 theses to the doors of wittenberg cathedral in 1517 protesting the catholic church ’ s corruption , he initiated a movement that would transform the religious , political , and artistic landscape of europe . for the next century , europe would be in turmoil as new political and religious boundaries were determined , often through bloody military conflicts . only in 1648 , with the signing of the treaty of westphalia , did the conflicts between protestants and catholics subside in continental europe . martin luther focused his critique on what he saw as the church ’ s greed and abuse of power . he called rome , the seat of papal power , “ the whore of babylon ” decked out in finery of expensive art , grand architecture , and sumptuous banquets . the church responded to the crisis in two ways : by internally addressing issues of corruption and by defending the doctrines rejected by the protestants . thus , while the first two decades of the 16th century were a period of lavish spending for the papacy , the middle decades were a period of austerity . as one visitor to rome noted in the 1560s , the entire city had become a convent . piety and asceticism ruled the day . by the end of the 16th century , the catholic church was once again feeling optimistic , even triumphant . it had emerged from the crisis with renewed vigor and clarity of purpose . shepherding the faithful—instructing them on catholic doctrines and inspiring virtuous behavior—took center stage . keen to rebuild rome ’ s reputation as a holy city , the papacy embarked on extensive building and decoration campaigns aimed at highlighting its ancient origins , its beliefs , and its divinely-sanctioned authority . in the eyes of faithful catholics , rome was not an unfaithful whore , but a pure bride , beautifully adorned for her union with her divine spouse . the art of persuasion : instruct , delight , move while the protestants harshly criticized the cult of images , the catholic church ardently embraced the religious power of art . the visual arts , the church argued , played a key role in guiding the faithful . they were certainly as important as the written and spoken word , and perhaps even more important since they were accessible to the learned and the unlearned alike . in order to be effective in its pastoral role , religious art had to be clear , persuasive , and powerful . not only did it have to instruct , it had to inspire . it had to move the faithful to feel the reality of christ ’ s sacrifice , the suffering of the martyrs , the visions of the saints . caravaggio , the crowning with thorns , 1602-04 , oil on canvas , 165.5 x 127 cm ( kunsthistorisches museum , vienna ) the church ’ s emphasis on art ’ s pastoral role prompted artists to experiment with new and more direct means of engaging the viewer . artists like caravaggio turned to a powerful and dramatic realism , accentuated by bold contrasts of light and dark , and tightly-cropped compositions that enhanced the physical and emotional immediacy of the depicted narrative . other artists , like annibale carracci—who also experimented with realism—ultimately settled on a more classical visual language , inspired by the vibrant palette , idealized forms , and balanced compositions of the high renaissance , see image above . still others , like giovanni battista gaulli , turned to daring feats of illusionism that blurred not only the boundaries between painting , sculpture , and architecture , but also those between the real and depicted worlds . in so doing , the divine was made physically present and palpable . whether through shocking realism , dynamic movement , or exuberant ornamentation , 17th-century art was meant to impress . it aimed to convince the viewer of the truth of its message by impacting the senses , awakening the emotions , and activating—even sharing—the viewer ’ s space . giovanni battista gaulli , also known as il baciccio , the triumph of the name of jesus , il , gesù ceiling fresco , 1672-1685 the catholic monarchs and their territories the monarchs of spain , portugal , and france also embraced the more ornate elements of 17th-century art to celebrate catholicism . in spain and its colonies , rulers invested vast resources on elaborate church facades , stunning , gold-covered chapels and tabernacles , and strikingly-realistic polychrome sculpture . in the spanish netherlands , where sacred art had suffered terribly as a result of the protestant iconoclasm—the destruction of art—civic and religious leaders prioritized the adornment of churches as the region reclaimed its catholic identity . refurnishing the altars of antwerp ’ s churches kept peter paul rubens ’ workshop busy for many years . europe ’ s monarchs also adopted this artistic vocabulary to proclaim their own power and status . louis xiv , for example , commissioned the splendid buildings and gardens of versailles as a visual expression of his divine right to rule . peter paul rubens , elevation of the cross , 1610 , oil on wood , 15 ft 1-7/8 in x 11 ft 1-1/2 in ( originally for saint walpurgis , antwerp [ destroyed ] , now in antwerp cathedral ) the protestant north in the protestant countries , and especially in the newly-independent dutch republic , modern-day holland , the artistic climate changed radically in the aftermath of the reformation . two of the wealthiest sources of patronage—the monarchy and the church—were now gone . in their stead arose an increasingly prosperous middle class eager to express its status and its new sense of national pride through the purchase of art . by the middle of the 17th century , a new market had emerged to meet the artistic tastes of this class . the demand was now for smaller-scale paintings suitable for display in private homes . these paintings included religious subjects for private contemplation , as seen in rembrandt ’ s poignant paintings and prints of biblical narratives , as well as portraits documenting individual likenesses . judith leyster , self-portrait , c. 1630 , oil on canvas , 651 x 746 cm ( national gallery of art , washington ) but , the greatest change in the market was the dramatic increase in the popularity of landscapes , still-lifes , and scenes of everyday life—known as genre painting . indeed , the proliferation of these subjects as independent artistic genres was one of the 17th century ’ s most significant contributions to the history of western art . in all of these genres , artists revealed a keen interest in replicating observed reality—whether it be the light on the dutch landscape , the momentary expression on a face , or the varied textures and materials of the objects the dutch collected as they reaped the benefits of their expanding mercantile empire . these works demonstrated as much artistic virtuosity and physical immediacy as the grand decorations of the palaces and churches of catholic europe . in the context of european history , the period from c. 1585 to c. 1700/1730 is often called the baroque era . the word baroque derives from the portuguese and spanish words for a large , irregularly-shaped pearl—barroco and barrueco , respectively . eighteenth-century critics were the first to apply the term to the art of the 17th century . it was not a term of praise . to the eyes of these critics , who favored the restraint and order of neoclassicism , the works of bernini , borromini , and pietro da cortona appeared bizarre , absurd , even diseased—in other words , misshapen , like an imperfect pearl . francisco de zurbarán , saint francis of assisi according to pope nicholas v 's vision , c. 1640 , oil on canvas , 110.5 x 180.5 cm ( museum nacional d'art de catalunya , barcelona ) baroque—the word , the style , the period by the middle of the 19th century , the word baroque had lost its pejorative implications and was used to describe the ornate and complex qualities present in many examples of 17th-century art , music , and literature . eventually , the term came to designate the historical period as a whole . in the context of painting , for example , the stark realism of zurbaran ’ s altarpieces , the quiet intimacy of vermeer ’ s domestic interiors , and the restrained classicism of poussin ’ s landscapes are all baroque—now with a capital b to indicate the historical period—regardless of the absence of the stylistic traits originally associated with the term . scholars continue to debate the validity of this label , admitting the usefulness of having a label for this distinct historical period , while also acknowledging its limitations in characterizing the variety of artistic styles present in the 17th century . essay by dr. esperança camara additional resources baroque rome on the metropolitan museum of art 's heilbrunn timeline of art history annibale carracci on the metropolitan museum of art 's heilbrunn timeline of art history
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it had to move the faithful to feel the reality of christ ’ s sacrifice , the suffering of the martyrs , the visions of the saints . caravaggio , the crowning with thorns , 1602-04 , oil on canvas , 165.5 x 127 cm ( kunsthistorisches museum , vienna ) the church ’ s emphasis on art ’ s pastoral role prompted artists to experiment with new and more direct means of engaging the viewer . artists like caravaggio turned to a powerful and dramatic realism , accentuated by bold contrasts of light and dark , and tightly-cropped compositions that enhanced the physical and emotional immediacy of the depicted narrative . other artists , like annibale carracci—who also experimented with realism—ultimately settled on a more classical visual language , inspired by the vibrant palette , idealized forms , and balanced compositions of the high renaissance , see image above . still others , like giovanni battista gaulli , turned to daring feats of illusionism that blurred not only the boundaries between painting , sculpture , and architecture , but also those between the real and depicted worlds .
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how common were these sorts of artists at the time ?
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gian lorenzo bernini ; view to cathedra petri ( chair of st. peter ) , gilded bronze , gold , wood , stained glass ; 1647-53 ( apse of saint peter 's basilica , vatican city , rome ) . image credit : steven zucker , cc by-nc-sa 2.0 rome : from the whore of babylon to the resplendent bride of christ when martin luther tacked his 95 theses to the doors of wittenberg cathedral in 1517 protesting the catholic church ’ s corruption , he initiated a movement that would transform the religious , political , and artistic landscape of europe . for the next century , europe would be in turmoil as new political and religious boundaries were determined , often through bloody military conflicts . only in 1648 , with the signing of the treaty of westphalia , did the conflicts between protestants and catholics subside in continental europe . martin luther focused his critique on what he saw as the church ’ s greed and abuse of power . he called rome , the seat of papal power , “ the whore of babylon ” decked out in finery of expensive art , grand architecture , and sumptuous banquets . the church responded to the crisis in two ways : by internally addressing issues of corruption and by defending the doctrines rejected by the protestants . thus , while the first two decades of the 16th century were a period of lavish spending for the papacy , the middle decades were a period of austerity . as one visitor to rome noted in the 1560s , the entire city had become a convent . piety and asceticism ruled the day . by the end of the 16th century , the catholic church was once again feeling optimistic , even triumphant . it had emerged from the crisis with renewed vigor and clarity of purpose . shepherding the faithful—instructing them on catholic doctrines and inspiring virtuous behavior—took center stage . keen to rebuild rome ’ s reputation as a holy city , the papacy embarked on extensive building and decoration campaigns aimed at highlighting its ancient origins , its beliefs , and its divinely-sanctioned authority . in the eyes of faithful catholics , rome was not an unfaithful whore , but a pure bride , beautifully adorned for her union with her divine spouse . the art of persuasion : instruct , delight , move while the protestants harshly criticized the cult of images , the catholic church ardently embraced the religious power of art . the visual arts , the church argued , played a key role in guiding the faithful . they were certainly as important as the written and spoken word , and perhaps even more important since they were accessible to the learned and the unlearned alike . in order to be effective in its pastoral role , religious art had to be clear , persuasive , and powerful . not only did it have to instruct , it had to inspire . it had to move the faithful to feel the reality of christ ’ s sacrifice , the suffering of the martyrs , the visions of the saints . caravaggio , the crowning with thorns , 1602-04 , oil on canvas , 165.5 x 127 cm ( kunsthistorisches museum , vienna ) the church ’ s emphasis on art ’ s pastoral role prompted artists to experiment with new and more direct means of engaging the viewer . artists like caravaggio turned to a powerful and dramatic realism , accentuated by bold contrasts of light and dark , and tightly-cropped compositions that enhanced the physical and emotional immediacy of the depicted narrative . other artists , like annibale carracci—who also experimented with realism—ultimately settled on a more classical visual language , inspired by the vibrant palette , idealized forms , and balanced compositions of the high renaissance , see image above . still others , like giovanni battista gaulli , turned to daring feats of illusionism that blurred not only the boundaries between painting , sculpture , and architecture , but also those between the real and depicted worlds . in so doing , the divine was made physically present and palpable . whether through shocking realism , dynamic movement , or exuberant ornamentation , 17th-century art was meant to impress . it aimed to convince the viewer of the truth of its message by impacting the senses , awakening the emotions , and activating—even sharing—the viewer ’ s space . giovanni battista gaulli , also known as il baciccio , the triumph of the name of jesus , il , gesù ceiling fresco , 1672-1685 the catholic monarchs and their territories the monarchs of spain , portugal , and france also embraced the more ornate elements of 17th-century art to celebrate catholicism . in spain and its colonies , rulers invested vast resources on elaborate church facades , stunning , gold-covered chapels and tabernacles , and strikingly-realistic polychrome sculpture . in the spanish netherlands , where sacred art had suffered terribly as a result of the protestant iconoclasm—the destruction of art—civic and religious leaders prioritized the adornment of churches as the region reclaimed its catholic identity . refurnishing the altars of antwerp ’ s churches kept peter paul rubens ’ workshop busy for many years . europe ’ s monarchs also adopted this artistic vocabulary to proclaim their own power and status . louis xiv , for example , commissioned the splendid buildings and gardens of versailles as a visual expression of his divine right to rule . peter paul rubens , elevation of the cross , 1610 , oil on wood , 15 ft 1-7/8 in x 11 ft 1-1/2 in ( originally for saint walpurgis , antwerp [ destroyed ] , now in antwerp cathedral ) the protestant north in the protestant countries , and especially in the newly-independent dutch republic , modern-day holland , the artistic climate changed radically in the aftermath of the reformation . two of the wealthiest sources of patronage—the monarchy and the church—were now gone . in their stead arose an increasingly prosperous middle class eager to express its status and its new sense of national pride through the purchase of art . by the middle of the 17th century , a new market had emerged to meet the artistic tastes of this class . the demand was now for smaller-scale paintings suitable for display in private homes . these paintings included religious subjects for private contemplation , as seen in rembrandt ’ s poignant paintings and prints of biblical narratives , as well as portraits documenting individual likenesses . judith leyster , self-portrait , c. 1630 , oil on canvas , 651 x 746 cm ( national gallery of art , washington ) but , the greatest change in the market was the dramatic increase in the popularity of landscapes , still-lifes , and scenes of everyday life—known as genre painting . indeed , the proliferation of these subjects as independent artistic genres was one of the 17th century ’ s most significant contributions to the history of western art . in all of these genres , artists revealed a keen interest in replicating observed reality—whether it be the light on the dutch landscape , the momentary expression on a face , or the varied textures and materials of the objects the dutch collected as they reaped the benefits of their expanding mercantile empire . these works demonstrated as much artistic virtuosity and physical immediacy as the grand decorations of the palaces and churches of catholic europe . in the context of european history , the period from c. 1585 to c. 1700/1730 is often called the baroque era . the word baroque derives from the portuguese and spanish words for a large , irregularly-shaped pearl—barroco and barrueco , respectively . eighteenth-century critics were the first to apply the term to the art of the 17th century . it was not a term of praise . to the eyes of these critics , who favored the restraint and order of neoclassicism , the works of bernini , borromini , and pietro da cortona appeared bizarre , absurd , even diseased—in other words , misshapen , like an imperfect pearl . francisco de zurbarán , saint francis of assisi according to pope nicholas v 's vision , c. 1640 , oil on canvas , 110.5 x 180.5 cm ( museum nacional d'art de catalunya , barcelona ) baroque—the word , the style , the period by the middle of the 19th century , the word baroque had lost its pejorative implications and was used to describe the ornate and complex qualities present in many examples of 17th-century art , music , and literature . eventually , the term came to designate the historical period as a whole . in the context of painting , for example , the stark realism of zurbaran ’ s altarpieces , the quiet intimacy of vermeer ’ s domestic interiors , and the restrained classicism of poussin ’ s landscapes are all baroque—now with a capital b to indicate the historical period—regardless of the absence of the stylistic traits originally associated with the term . scholars continue to debate the validity of this label , admitting the usefulness of having a label for this distinct historical period , while also acknowledging its limitations in characterizing the variety of artistic styles present in the 17th century . essay by dr. esperança camara additional resources baroque rome on the metropolitan museum of art 's heilbrunn timeline of art history annibale carracci on the metropolitan museum of art 's heilbrunn timeline of art history
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scholars continue to debate the validity of this label , admitting the usefulness of having a label for this distinct historical period , while also acknowledging its limitations in characterizing the variety of artistic styles present in the 17th century . essay by dr. esperança camara additional resources baroque rome on the metropolitan museum of art 's heilbrunn timeline of art history annibale carracci on the metropolitan museum of art 's heilbrunn timeline of art history
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is the barroque art movement part of the rennaissance or is it alright to say that the renaissance was strictly chatolic art and the barroque was on the side of protestantism ?
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gian lorenzo bernini ; view to cathedra petri ( chair of st. peter ) , gilded bronze , gold , wood , stained glass ; 1647-53 ( apse of saint peter 's basilica , vatican city , rome ) . image credit : steven zucker , cc by-nc-sa 2.0 rome : from the whore of babylon to the resplendent bride of christ when martin luther tacked his 95 theses to the doors of wittenberg cathedral in 1517 protesting the catholic church ’ s corruption , he initiated a movement that would transform the religious , political , and artistic landscape of europe . for the next century , europe would be in turmoil as new political and religious boundaries were determined , often through bloody military conflicts . only in 1648 , with the signing of the treaty of westphalia , did the conflicts between protestants and catholics subside in continental europe . martin luther focused his critique on what he saw as the church ’ s greed and abuse of power . he called rome , the seat of papal power , “ the whore of babylon ” decked out in finery of expensive art , grand architecture , and sumptuous banquets . the church responded to the crisis in two ways : by internally addressing issues of corruption and by defending the doctrines rejected by the protestants . thus , while the first two decades of the 16th century were a period of lavish spending for the papacy , the middle decades were a period of austerity . as one visitor to rome noted in the 1560s , the entire city had become a convent . piety and asceticism ruled the day . by the end of the 16th century , the catholic church was once again feeling optimistic , even triumphant . it had emerged from the crisis with renewed vigor and clarity of purpose . shepherding the faithful—instructing them on catholic doctrines and inspiring virtuous behavior—took center stage . keen to rebuild rome ’ s reputation as a holy city , the papacy embarked on extensive building and decoration campaigns aimed at highlighting its ancient origins , its beliefs , and its divinely-sanctioned authority . in the eyes of faithful catholics , rome was not an unfaithful whore , but a pure bride , beautifully adorned for her union with her divine spouse . the art of persuasion : instruct , delight , move while the protestants harshly criticized the cult of images , the catholic church ardently embraced the religious power of art . the visual arts , the church argued , played a key role in guiding the faithful . they were certainly as important as the written and spoken word , and perhaps even more important since they were accessible to the learned and the unlearned alike . in order to be effective in its pastoral role , religious art had to be clear , persuasive , and powerful . not only did it have to instruct , it had to inspire . it had to move the faithful to feel the reality of christ ’ s sacrifice , the suffering of the martyrs , the visions of the saints . caravaggio , the crowning with thorns , 1602-04 , oil on canvas , 165.5 x 127 cm ( kunsthistorisches museum , vienna ) the church ’ s emphasis on art ’ s pastoral role prompted artists to experiment with new and more direct means of engaging the viewer . artists like caravaggio turned to a powerful and dramatic realism , accentuated by bold contrasts of light and dark , and tightly-cropped compositions that enhanced the physical and emotional immediacy of the depicted narrative . other artists , like annibale carracci—who also experimented with realism—ultimately settled on a more classical visual language , inspired by the vibrant palette , idealized forms , and balanced compositions of the high renaissance , see image above . still others , like giovanni battista gaulli , turned to daring feats of illusionism that blurred not only the boundaries between painting , sculpture , and architecture , but also those between the real and depicted worlds . in so doing , the divine was made physically present and palpable . whether through shocking realism , dynamic movement , or exuberant ornamentation , 17th-century art was meant to impress . it aimed to convince the viewer of the truth of its message by impacting the senses , awakening the emotions , and activating—even sharing—the viewer ’ s space . giovanni battista gaulli , also known as il baciccio , the triumph of the name of jesus , il , gesù ceiling fresco , 1672-1685 the catholic monarchs and their territories the monarchs of spain , portugal , and france also embraced the more ornate elements of 17th-century art to celebrate catholicism . in spain and its colonies , rulers invested vast resources on elaborate church facades , stunning , gold-covered chapels and tabernacles , and strikingly-realistic polychrome sculpture . in the spanish netherlands , where sacred art had suffered terribly as a result of the protestant iconoclasm—the destruction of art—civic and religious leaders prioritized the adornment of churches as the region reclaimed its catholic identity . refurnishing the altars of antwerp ’ s churches kept peter paul rubens ’ workshop busy for many years . europe ’ s monarchs also adopted this artistic vocabulary to proclaim their own power and status . louis xiv , for example , commissioned the splendid buildings and gardens of versailles as a visual expression of his divine right to rule . peter paul rubens , elevation of the cross , 1610 , oil on wood , 15 ft 1-7/8 in x 11 ft 1-1/2 in ( originally for saint walpurgis , antwerp [ destroyed ] , now in antwerp cathedral ) the protestant north in the protestant countries , and especially in the newly-independent dutch republic , modern-day holland , the artistic climate changed radically in the aftermath of the reformation . two of the wealthiest sources of patronage—the monarchy and the church—were now gone . in their stead arose an increasingly prosperous middle class eager to express its status and its new sense of national pride through the purchase of art . by the middle of the 17th century , a new market had emerged to meet the artistic tastes of this class . the demand was now for smaller-scale paintings suitable for display in private homes . these paintings included religious subjects for private contemplation , as seen in rembrandt ’ s poignant paintings and prints of biblical narratives , as well as portraits documenting individual likenesses . judith leyster , self-portrait , c. 1630 , oil on canvas , 651 x 746 cm ( national gallery of art , washington ) but , the greatest change in the market was the dramatic increase in the popularity of landscapes , still-lifes , and scenes of everyday life—known as genre painting . indeed , the proliferation of these subjects as independent artistic genres was one of the 17th century ’ s most significant contributions to the history of western art . in all of these genres , artists revealed a keen interest in replicating observed reality—whether it be the light on the dutch landscape , the momentary expression on a face , or the varied textures and materials of the objects the dutch collected as they reaped the benefits of their expanding mercantile empire . these works demonstrated as much artistic virtuosity and physical immediacy as the grand decorations of the palaces and churches of catholic europe . in the context of european history , the period from c. 1585 to c. 1700/1730 is often called the baroque era . the word baroque derives from the portuguese and spanish words for a large , irregularly-shaped pearl—barroco and barrueco , respectively . eighteenth-century critics were the first to apply the term to the art of the 17th century . it was not a term of praise . to the eyes of these critics , who favored the restraint and order of neoclassicism , the works of bernini , borromini , and pietro da cortona appeared bizarre , absurd , even diseased—in other words , misshapen , like an imperfect pearl . francisco de zurbarán , saint francis of assisi according to pope nicholas v 's vision , c. 1640 , oil on canvas , 110.5 x 180.5 cm ( museum nacional d'art de catalunya , barcelona ) baroque—the word , the style , the period by the middle of the 19th century , the word baroque had lost its pejorative implications and was used to describe the ornate and complex qualities present in many examples of 17th-century art , music , and literature . eventually , the term came to designate the historical period as a whole . in the context of painting , for example , the stark realism of zurbaran ’ s altarpieces , the quiet intimacy of vermeer ’ s domestic interiors , and the restrained classicism of poussin ’ s landscapes are all baroque—now with a capital b to indicate the historical period—regardless of the absence of the stylistic traits originally associated with the term . scholars continue to debate the validity of this label , admitting the usefulness of having a label for this distinct historical period , while also acknowledging its limitations in characterizing the variety of artistic styles present in the 17th century . essay by dr. esperança camara additional resources baroque rome on the metropolitan museum of art 's heilbrunn timeline of art history annibale carracci on the metropolitan museum of art 's heilbrunn timeline of art history
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the art of persuasion : instruct , delight , move while the protestants harshly criticized the cult of images , the catholic church ardently embraced the religious power of art . the visual arts , the church argued , played a key role in guiding the faithful . they were certainly as important as the written and spoken word , and perhaps even more important since they were accessible to the learned and the unlearned alike .
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can you expand the visual presentation by including a print of the artist ?
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gian lorenzo bernini ; view to cathedra petri ( chair of st. peter ) , gilded bronze , gold , wood , stained glass ; 1647-53 ( apse of saint peter 's basilica , vatican city , rome ) . image credit : steven zucker , cc by-nc-sa 2.0 rome : from the whore of babylon to the resplendent bride of christ when martin luther tacked his 95 theses to the doors of wittenberg cathedral in 1517 protesting the catholic church ’ s corruption , he initiated a movement that would transform the religious , political , and artistic landscape of europe . for the next century , europe would be in turmoil as new political and religious boundaries were determined , often through bloody military conflicts . only in 1648 , with the signing of the treaty of westphalia , did the conflicts between protestants and catholics subside in continental europe . martin luther focused his critique on what he saw as the church ’ s greed and abuse of power . he called rome , the seat of papal power , “ the whore of babylon ” decked out in finery of expensive art , grand architecture , and sumptuous banquets . the church responded to the crisis in two ways : by internally addressing issues of corruption and by defending the doctrines rejected by the protestants . thus , while the first two decades of the 16th century were a period of lavish spending for the papacy , the middle decades were a period of austerity . as one visitor to rome noted in the 1560s , the entire city had become a convent . piety and asceticism ruled the day . by the end of the 16th century , the catholic church was once again feeling optimistic , even triumphant . it had emerged from the crisis with renewed vigor and clarity of purpose . shepherding the faithful—instructing them on catholic doctrines and inspiring virtuous behavior—took center stage . keen to rebuild rome ’ s reputation as a holy city , the papacy embarked on extensive building and decoration campaigns aimed at highlighting its ancient origins , its beliefs , and its divinely-sanctioned authority . in the eyes of faithful catholics , rome was not an unfaithful whore , but a pure bride , beautifully adorned for her union with her divine spouse . the art of persuasion : instruct , delight , move while the protestants harshly criticized the cult of images , the catholic church ardently embraced the religious power of art . the visual arts , the church argued , played a key role in guiding the faithful . they were certainly as important as the written and spoken word , and perhaps even more important since they were accessible to the learned and the unlearned alike . in order to be effective in its pastoral role , religious art had to be clear , persuasive , and powerful . not only did it have to instruct , it had to inspire . it had to move the faithful to feel the reality of christ ’ s sacrifice , the suffering of the martyrs , the visions of the saints . caravaggio , the crowning with thorns , 1602-04 , oil on canvas , 165.5 x 127 cm ( kunsthistorisches museum , vienna ) the church ’ s emphasis on art ’ s pastoral role prompted artists to experiment with new and more direct means of engaging the viewer . artists like caravaggio turned to a powerful and dramatic realism , accentuated by bold contrasts of light and dark , and tightly-cropped compositions that enhanced the physical and emotional immediacy of the depicted narrative . other artists , like annibale carracci—who also experimented with realism—ultimately settled on a more classical visual language , inspired by the vibrant palette , idealized forms , and balanced compositions of the high renaissance , see image above . still others , like giovanni battista gaulli , turned to daring feats of illusionism that blurred not only the boundaries between painting , sculpture , and architecture , but also those between the real and depicted worlds . in so doing , the divine was made physically present and palpable . whether through shocking realism , dynamic movement , or exuberant ornamentation , 17th-century art was meant to impress . it aimed to convince the viewer of the truth of its message by impacting the senses , awakening the emotions , and activating—even sharing—the viewer ’ s space . giovanni battista gaulli , also known as il baciccio , the triumph of the name of jesus , il , gesù ceiling fresco , 1672-1685 the catholic monarchs and their territories the monarchs of spain , portugal , and france also embraced the more ornate elements of 17th-century art to celebrate catholicism . in spain and its colonies , rulers invested vast resources on elaborate church facades , stunning , gold-covered chapels and tabernacles , and strikingly-realistic polychrome sculpture . in the spanish netherlands , where sacred art had suffered terribly as a result of the protestant iconoclasm—the destruction of art—civic and religious leaders prioritized the adornment of churches as the region reclaimed its catholic identity . refurnishing the altars of antwerp ’ s churches kept peter paul rubens ’ workshop busy for many years . europe ’ s monarchs also adopted this artistic vocabulary to proclaim their own power and status . louis xiv , for example , commissioned the splendid buildings and gardens of versailles as a visual expression of his divine right to rule . peter paul rubens , elevation of the cross , 1610 , oil on wood , 15 ft 1-7/8 in x 11 ft 1-1/2 in ( originally for saint walpurgis , antwerp [ destroyed ] , now in antwerp cathedral ) the protestant north in the protestant countries , and especially in the newly-independent dutch republic , modern-day holland , the artistic climate changed radically in the aftermath of the reformation . two of the wealthiest sources of patronage—the monarchy and the church—were now gone . in their stead arose an increasingly prosperous middle class eager to express its status and its new sense of national pride through the purchase of art . by the middle of the 17th century , a new market had emerged to meet the artistic tastes of this class . the demand was now for smaller-scale paintings suitable for display in private homes . these paintings included religious subjects for private contemplation , as seen in rembrandt ’ s poignant paintings and prints of biblical narratives , as well as portraits documenting individual likenesses . judith leyster , self-portrait , c. 1630 , oil on canvas , 651 x 746 cm ( national gallery of art , washington ) but , the greatest change in the market was the dramatic increase in the popularity of landscapes , still-lifes , and scenes of everyday life—known as genre painting . indeed , the proliferation of these subjects as independent artistic genres was one of the 17th century ’ s most significant contributions to the history of western art . in all of these genres , artists revealed a keen interest in replicating observed reality—whether it be the light on the dutch landscape , the momentary expression on a face , or the varied textures and materials of the objects the dutch collected as they reaped the benefits of their expanding mercantile empire . these works demonstrated as much artistic virtuosity and physical immediacy as the grand decorations of the palaces and churches of catholic europe . in the context of european history , the period from c. 1585 to c. 1700/1730 is often called the baroque era . the word baroque derives from the portuguese and spanish words for a large , irregularly-shaped pearl—barroco and barrueco , respectively . eighteenth-century critics were the first to apply the term to the art of the 17th century . it was not a term of praise . to the eyes of these critics , who favored the restraint and order of neoclassicism , the works of bernini , borromini , and pietro da cortona appeared bizarre , absurd , even diseased—in other words , misshapen , like an imperfect pearl . francisco de zurbarán , saint francis of assisi according to pope nicholas v 's vision , c. 1640 , oil on canvas , 110.5 x 180.5 cm ( museum nacional d'art de catalunya , barcelona ) baroque—the word , the style , the period by the middle of the 19th century , the word baroque had lost its pejorative implications and was used to describe the ornate and complex qualities present in many examples of 17th-century art , music , and literature . eventually , the term came to designate the historical period as a whole . in the context of painting , for example , the stark realism of zurbaran ’ s altarpieces , the quiet intimacy of vermeer ’ s domestic interiors , and the restrained classicism of poussin ’ s landscapes are all baroque—now with a capital b to indicate the historical period—regardless of the absence of the stylistic traits originally associated with the term . scholars continue to debate the validity of this label , admitting the usefulness of having a label for this distinct historical period , while also acknowledging its limitations in characterizing the variety of artistic styles present in the 17th century . essay by dr. esperança camara additional resources baroque rome on the metropolitan museum of art 's heilbrunn timeline of art history annibale carracci on the metropolitan museum of art 's heilbrunn timeline of art history
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these paintings included religious subjects for private contemplation , as seen in rembrandt ’ s poignant paintings and prints of biblical narratives , as well as portraits documenting individual likenesses . judith leyster , self-portrait , c. 1630 , oil on canvas , 651 x 746 cm ( national gallery of art , washington ) but , the greatest change in the market was the dramatic increase in the popularity of landscapes , still-lifes , and scenes of everyday life—known as genre painting . indeed , the proliferation of these subjects as independent artistic genres was one of the 17th century ’ s most significant contributions to the history of western art .
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i was just looking at judith leyster 's self-portrait , and was wondering if it would have been frowned upon for her to paint , or if it was something that was acceptable and normal ?
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gian lorenzo bernini ; view to cathedra petri ( chair of st. peter ) , gilded bronze , gold , wood , stained glass ; 1647-53 ( apse of saint peter 's basilica , vatican city , rome ) . image credit : steven zucker , cc by-nc-sa 2.0 rome : from the whore of babylon to the resplendent bride of christ when martin luther tacked his 95 theses to the doors of wittenberg cathedral in 1517 protesting the catholic church ’ s corruption , he initiated a movement that would transform the religious , political , and artistic landscape of europe . for the next century , europe would be in turmoil as new political and religious boundaries were determined , often through bloody military conflicts . only in 1648 , with the signing of the treaty of westphalia , did the conflicts between protestants and catholics subside in continental europe . martin luther focused his critique on what he saw as the church ’ s greed and abuse of power . he called rome , the seat of papal power , “ the whore of babylon ” decked out in finery of expensive art , grand architecture , and sumptuous banquets . the church responded to the crisis in two ways : by internally addressing issues of corruption and by defending the doctrines rejected by the protestants . thus , while the first two decades of the 16th century were a period of lavish spending for the papacy , the middle decades were a period of austerity . as one visitor to rome noted in the 1560s , the entire city had become a convent . piety and asceticism ruled the day . by the end of the 16th century , the catholic church was once again feeling optimistic , even triumphant . it had emerged from the crisis with renewed vigor and clarity of purpose . shepherding the faithful—instructing them on catholic doctrines and inspiring virtuous behavior—took center stage . keen to rebuild rome ’ s reputation as a holy city , the papacy embarked on extensive building and decoration campaigns aimed at highlighting its ancient origins , its beliefs , and its divinely-sanctioned authority . in the eyes of faithful catholics , rome was not an unfaithful whore , but a pure bride , beautifully adorned for her union with her divine spouse . the art of persuasion : instruct , delight , move while the protestants harshly criticized the cult of images , the catholic church ardently embraced the religious power of art . the visual arts , the church argued , played a key role in guiding the faithful . they were certainly as important as the written and spoken word , and perhaps even more important since they were accessible to the learned and the unlearned alike . in order to be effective in its pastoral role , religious art had to be clear , persuasive , and powerful . not only did it have to instruct , it had to inspire . it had to move the faithful to feel the reality of christ ’ s sacrifice , the suffering of the martyrs , the visions of the saints . caravaggio , the crowning with thorns , 1602-04 , oil on canvas , 165.5 x 127 cm ( kunsthistorisches museum , vienna ) the church ’ s emphasis on art ’ s pastoral role prompted artists to experiment with new and more direct means of engaging the viewer . artists like caravaggio turned to a powerful and dramatic realism , accentuated by bold contrasts of light and dark , and tightly-cropped compositions that enhanced the physical and emotional immediacy of the depicted narrative . other artists , like annibale carracci—who also experimented with realism—ultimately settled on a more classical visual language , inspired by the vibrant palette , idealized forms , and balanced compositions of the high renaissance , see image above . still others , like giovanni battista gaulli , turned to daring feats of illusionism that blurred not only the boundaries between painting , sculpture , and architecture , but also those between the real and depicted worlds . in so doing , the divine was made physically present and palpable . whether through shocking realism , dynamic movement , or exuberant ornamentation , 17th-century art was meant to impress . it aimed to convince the viewer of the truth of its message by impacting the senses , awakening the emotions , and activating—even sharing—the viewer ’ s space . giovanni battista gaulli , also known as il baciccio , the triumph of the name of jesus , il , gesù ceiling fresco , 1672-1685 the catholic monarchs and their territories the monarchs of spain , portugal , and france also embraced the more ornate elements of 17th-century art to celebrate catholicism . in spain and its colonies , rulers invested vast resources on elaborate church facades , stunning , gold-covered chapels and tabernacles , and strikingly-realistic polychrome sculpture . in the spanish netherlands , where sacred art had suffered terribly as a result of the protestant iconoclasm—the destruction of art—civic and religious leaders prioritized the adornment of churches as the region reclaimed its catholic identity . refurnishing the altars of antwerp ’ s churches kept peter paul rubens ’ workshop busy for many years . europe ’ s monarchs also adopted this artistic vocabulary to proclaim their own power and status . louis xiv , for example , commissioned the splendid buildings and gardens of versailles as a visual expression of his divine right to rule . peter paul rubens , elevation of the cross , 1610 , oil on wood , 15 ft 1-7/8 in x 11 ft 1-1/2 in ( originally for saint walpurgis , antwerp [ destroyed ] , now in antwerp cathedral ) the protestant north in the protestant countries , and especially in the newly-independent dutch republic , modern-day holland , the artistic climate changed radically in the aftermath of the reformation . two of the wealthiest sources of patronage—the monarchy and the church—were now gone . in their stead arose an increasingly prosperous middle class eager to express its status and its new sense of national pride through the purchase of art . by the middle of the 17th century , a new market had emerged to meet the artistic tastes of this class . the demand was now for smaller-scale paintings suitable for display in private homes . these paintings included religious subjects for private contemplation , as seen in rembrandt ’ s poignant paintings and prints of biblical narratives , as well as portraits documenting individual likenesses . judith leyster , self-portrait , c. 1630 , oil on canvas , 651 x 746 cm ( national gallery of art , washington ) but , the greatest change in the market was the dramatic increase in the popularity of landscapes , still-lifes , and scenes of everyday life—known as genre painting . indeed , the proliferation of these subjects as independent artistic genres was one of the 17th century ’ s most significant contributions to the history of western art . in all of these genres , artists revealed a keen interest in replicating observed reality—whether it be the light on the dutch landscape , the momentary expression on a face , or the varied textures and materials of the objects the dutch collected as they reaped the benefits of their expanding mercantile empire . these works demonstrated as much artistic virtuosity and physical immediacy as the grand decorations of the palaces and churches of catholic europe . in the context of european history , the period from c. 1585 to c. 1700/1730 is often called the baroque era . the word baroque derives from the portuguese and spanish words for a large , irregularly-shaped pearl—barroco and barrueco , respectively . eighteenth-century critics were the first to apply the term to the art of the 17th century . it was not a term of praise . to the eyes of these critics , who favored the restraint and order of neoclassicism , the works of bernini , borromini , and pietro da cortona appeared bizarre , absurd , even diseased—in other words , misshapen , like an imperfect pearl . francisco de zurbarán , saint francis of assisi according to pope nicholas v 's vision , c. 1640 , oil on canvas , 110.5 x 180.5 cm ( museum nacional d'art de catalunya , barcelona ) baroque—the word , the style , the period by the middle of the 19th century , the word baroque had lost its pejorative implications and was used to describe the ornate and complex qualities present in many examples of 17th-century art , music , and literature . eventually , the term came to designate the historical period as a whole . in the context of painting , for example , the stark realism of zurbaran ’ s altarpieces , the quiet intimacy of vermeer ’ s domestic interiors , and the restrained classicism of poussin ’ s landscapes are all baroque—now with a capital b to indicate the historical period—regardless of the absence of the stylistic traits originally associated with the term . scholars continue to debate the validity of this label , admitting the usefulness of having a label for this distinct historical period , while also acknowledging its limitations in characterizing the variety of artistic styles present in the 17th century . essay by dr. esperança camara additional resources baroque rome on the metropolitan museum of art 's heilbrunn timeline of art history annibale carracci on the metropolitan museum of art 's heilbrunn timeline of art history
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scholars continue to debate the validity of this label , admitting the usefulness of having a label for this distinct historical period , while also acknowledging its limitations in characterizing the variety of artistic styles present in the 17th century . essay by dr. esperança camara additional resources baroque rome on the metropolitan museum of art 's heilbrunn timeline of art history annibale carracci on the metropolitan museum of art 's heilbrunn timeline of art history
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in the twelfth paragraph under the protestant north if neoclassical artists thought baroque era art was like a '' imperfect pearl '' then why is it still around today ?
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gian lorenzo bernini ; view to cathedra petri ( chair of st. peter ) , gilded bronze , gold , wood , stained glass ; 1647-53 ( apse of saint peter 's basilica , vatican city , rome ) . image credit : steven zucker , cc by-nc-sa 2.0 rome : from the whore of babylon to the resplendent bride of christ when martin luther tacked his 95 theses to the doors of wittenberg cathedral in 1517 protesting the catholic church ’ s corruption , he initiated a movement that would transform the religious , political , and artistic landscape of europe . for the next century , europe would be in turmoil as new political and religious boundaries were determined , often through bloody military conflicts . only in 1648 , with the signing of the treaty of westphalia , did the conflicts between protestants and catholics subside in continental europe . martin luther focused his critique on what he saw as the church ’ s greed and abuse of power . he called rome , the seat of papal power , “ the whore of babylon ” decked out in finery of expensive art , grand architecture , and sumptuous banquets . the church responded to the crisis in two ways : by internally addressing issues of corruption and by defending the doctrines rejected by the protestants . thus , while the first two decades of the 16th century were a period of lavish spending for the papacy , the middle decades were a period of austerity . as one visitor to rome noted in the 1560s , the entire city had become a convent . piety and asceticism ruled the day . by the end of the 16th century , the catholic church was once again feeling optimistic , even triumphant . it had emerged from the crisis with renewed vigor and clarity of purpose . shepherding the faithful—instructing them on catholic doctrines and inspiring virtuous behavior—took center stage . keen to rebuild rome ’ s reputation as a holy city , the papacy embarked on extensive building and decoration campaigns aimed at highlighting its ancient origins , its beliefs , and its divinely-sanctioned authority . in the eyes of faithful catholics , rome was not an unfaithful whore , but a pure bride , beautifully adorned for her union with her divine spouse . the art of persuasion : instruct , delight , move while the protestants harshly criticized the cult of images , the catholic church ardently embraced the religious power of art . the visual arts , the church argued , played a key role in guiding the faithful . they were certainly as important as the written and spoken word , and perhaps even more important since they were accessible to the learned and the unlearned alike . in order to be effective in its pastoral role , religious art had to be clear , persuasive , and powerful . not only did it have to instruct , it had to inspire . it had to move the faithful to feel the reality of christ ’ s sacrifice , the suffering of the martyrs , the visions of the saints . caravaggio , the crowning with thorns , 1602-04 , oil on canvas , 165.5 x 127 cm ( kunsthistorisches museum , vienna ) the church ’ s emphasis on art ’ s pastoral role prompted artists to experiment with new and more direct means of engaging the viewer . artists like caravaggio turned to a powerful and dramatic realism , accentuated by bold contrasts of light and dark , and tightly-cropped compositions that enhanced the physical and emotional immediacy of the depicted narrative . other artists , like annibale carracci—who also experimented with realism—ultimately settled on a more classical visual language , inspired by the vibrant palette , idealized forms , and balanced compositions of the high renaissance , see image above . still others , like giovanni battista gaulli , turned to daring feats of illusionism that blurred not only the boundaries between painting , sculpture , and architecture , but also those between the real and depicted worlds . in so doing , the divine was made physically present and palpable . whether through shocking realism , dynamic movement , or exuberant ornamentation , 17th-century art was meant to impress . it aimed to convince the viewer of the truth of its message by impacting the senses , awakening the emotions , and activating—even sharing—the viewer ’ s space . giovanni battista gaulli , also known as il baciccio , the triumph of the name of jesus , il , gesù ceiling fresco , 1672-1685 the catholic monarchs and their territories the monarchs of spain , portugal , and france also embraced the more ornate elements of 17th-century art to celebrate catholicism . in spain and its colonies , rulers invested vast resources on elaborate church facades , stunning , gold-covered chapels and tabernacles , and strikingly-realistic polychrome sculpture . in the spanish netherlands , where sacred art had suffered terribly as a result of the protestant iconoclasm—the destruction of art—civic and religious leaders prioritized the adornment of churches as the region reclaimed its catholic identity . refurnishing the altars of antwerp ’ s churches kept peter paul rubens ’ workshop busy for many years . europe ’ s monarchs also adopted this artistic vocabulary to proclaim their own power and status . louis xiv , for example , commissioned the splendid buildings and gardens of versailles as a visual expression of his divine right to rule . peter paul rubens , elevation of the cross , 1610 , oil on wood , 15 ft 1-7/8 in x 11 ft 1-1/2 in ( originally for saint walpurgis , antwerp [ destroyed ] , now in antwerp cathedral ) the protestant north in the protestant countries , and especially in the newly-independent dutch republic , modern-day holland , the artistic climate changed radically in the aftermath of the reformation . two of the wealthiest sources of patronage—the monarchy and the church—were now gone . in their stead arose an increasingly prosperous middle class eager to express its status and its new sense of national pride through the purchase of art . by the middle of the 17th century , a new market had emerged to meet the artistic tastes of this class . the demand was now for smaller-scale paintings suitable for display in private homes . these paintings included religious subjects for private contemplation , as seen in rembrandt ’ s poignant paintings and prints of biblical narratives , as well as portraits documenting individual likenesses . judith leyster , self-portrait , c. 1630 , oil on canvas , 651 x 746 cm ( national gallery of art , washington ) but , the greatest change in the market was the dramatic increase in the popularity of landscapes , still-lifes , and scenes of everyday life—known as genre painting . indeed , the proliferation of these subjects as independent artistic genres was one of the 17th century ’ s most significant contributions to the history of western art . in all of these genres , artists revealed a keen interest in replicating observed reality—whether it be the light on the dutch landscape , the momentary expression on a face , or the varied textures and materials of the objects the dutch collected as they reaped the benefits of their expanding mercantile empire . these works demonstrated as much artistic virtuosity and physical immediacy as the grand decorations of the palaces and churches of catholic europe . in the context of european history , the period from c. 1585 to c. 1700/1730 is often called the baroque era . the word baroque derives from the portuguese and spanish words for a large , irregularly-shaped pearl—barroco and barrueco , respectively . eighteenth-century critics were the first to apply the term to the art of the 17th century . it was not a term of praise . to the eyes of these critics , who favored the restraint and order of neoclassicism , the works of bernini , borromini , and pietro da cortona appeared bizarre , absurd , even diseased—in other words , misshapen , like an imperfect pearl . francisco de zurbarán , saint francis of assisi according to pope nicholas v 's vision , c. 1640 , oil on canvas , 110.5 x 180.5 cm ( museum nacional d'art de catalunya , barcelona ) baroque—the word , the style , the period by the middle of the 19th century , the word baroque had lost its pejorative implications and was used to describe the ornate and complex qualities present in many examples of 17th-century art , music , and literature . eventually , the term came to designate the historical period as a whole . in the context of painting , for example , the stark realism of zurbaran ’ s altarpieces , the quiet intimacy of vermeer ’ s domestic interiors , and the restrained classicism of poussin ’ s landscapes are all baroque—now with a capital b to indicate the historical period—regardless of the absence of the stylistic traits originally associated with the term . scholars continue to debate the validity of this label , admitting the usefulness of having a label for this distinct historical period , while also acknowledging its limitations in characterizing the variety of artistic styles present in the 17th century . essay by dr. esperança camara additional resources baroque rome on the metropolitan museum of art 's heilbrunn timeline of art history annibale carracci on the metropolitan museum of art 's heilbrunn timeline of art history
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these works demonstrated as much artistic virtuosity and physical immediacy as the grand decorations of the palaces and churches of catholic europe . in the context of european history , the period from c. 1585 to c. 1700/1730 is often called the baroque era . the word baroque derives from the portuguese and spanish words for a large , irregularly-shaped pearl—barroco and barrueco , respectively .
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can someone explain the social context of baroque period ?
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gian lorenzo bernini ; view to cathedra petri ( chair of st. peter ) , gilded bronze , gold , wood , stained glass ; 1647-53 ( apse of saint peter 's basilica , vatican city , rome ) . image credit : steven zucker , cc by-nc-sa 2.0 rome : from the whore of babylon to the resplendent bride of christ when martin luther tacked his 95 theses to the doors of wittenberg cathedral in 1517 protesting the catholic church ’ s corruption , he initiated a movement that would transform the religious , political , and artistic landscape of europe . for the next century , europe would be in turmoil as new political and religious boundaries were determined , often through bloody military conflicts . only in 1648 , with the signing of the treaty of westphalia , did the conflicts between protestants and catholics subside in continental europe . martin luther focused his critique on what he saw as the church ’ s greed and abuse of power . he called rome , the seat of papal power , “ the whore of babylon ” decked out in finery of expensive art , grand architecture , and sumptuous banquets . the church responded to the crisis in two ways : by internally addressing issues of corruption and by defending the doctrines rejected by the protestants . thus , while the first two decades of the 16th century were a period of lavish spending for the papacy , the middle decades were a period of austerity . as one visitor to rome noted in the 1560s , the entire city had become a convent . piety and asceticism ruled the day . by the end of the 16th century , the catholic church was once again feeling optimistic , even triumphant . it had emerged from the crisis with renewed vigor and clarity of purpose . shepherding the faithful—instructing them on catholic doctrines and inspiring virtuous behavior—took center stage . keen to rebuild rome ’ s reputation as a holy city , the papacy embarked on extensive building and decoration campaigns aimed at highlighting its ancient origins , its beliefs , and its divinely-sanctioned authority . in the eyes of faithful catholics , rome was not an unfaithful whore , but a pure bride , beautifully adorned for her union with her divine spouse . the art of persuasion : instruct , delight , move while the protestants harshly criticized the cult of images , the catholic church ardently embraced the religious power of art . the visual arts , the church argued , played a key role in guiding the faithful . they were certainly as important as the written and spoken word , and perhaps even more important since they were accessible to the learned and the unlearned alike . in order to be effective in its pastoral role , religious art had to be clear , persuasive , and powerful . not only did it have to instruct , it had to inspire . it had to move the faithful to feel the reality of christ ’ s sacrifice , the suffering of the martyrs , the visions of the saints . caravaggio , the crowning with thorns , 1602-04 , oil on canvas , 165.5 x 127 cm ( kunsthistorisches museum , vienna ) the church ’ s emphasis on art ’ s pastoral role prompted artists to experiment with new and more direct means of engaging the viewer . artists like caravaggio turned to a powerful and dramatic realism , accentuated by bold contrasts of light and dark , and tightly-cropped compositions that enhanced the physical and emotional immediacy of the depicted narrative . other artists , like annibale carracci—who also experimented with realism—ultimately settled on a more classical visual language , inspired by the vibrant palette , idealized forms , and balanced compositions of the high renaissance , see image above . still others , like giovanni battista gaulli , turned to daring feats of illusionism that blurred not only the boundaries between painting , sculpture , and architecture , but also those between the real and depicted worlds . in so doing , the divine was made physically present and palpable . whether through shocking realism , dynamic movement , or exuberant ornamentation , 17th-century art was meant to impress . it aimed to convince the viewer of the truth of its message by impacting the senses , awakening the emotions , and activating—even sharing—the viewer ’ s space . giovanni battista gaulli , also known as il baciccio , the triumph of the name of jesus , il , gesù ceiling fresco , 1672-1685 the catholic monarchs and their territories the monarchs of spain , portugal , and france also embraced the more ornate elements of 17th-century art to celebrate catholicism . in spain and its colonies , rulers invested vast resources on elaborate church facades , stunning , gold-covered chapels and tabernacles , and strikingly-realistic polychrome sculpture . in the spanish netherlands , where sacred art had suffered terribly as a result of the protestant iconoclasm—the destruction of art—civic and religious leaders prioritized the adornment of churches as the region reclaimed its catholic identity . refurnishing the altars of antwerp ’ s churches kept peter paul rubens ’ workshop busy for many years . europe ’ s monarchs also adopted this artistic vocabulary to proclaim their own power and status . louis xiv , for example , commissioned the splendid buildings and gardens of versailles as a visual expression of his divine right to rule . peter paul rubens , elevation of the cross , 1610 , oil on wood , 15 ft 1-7/8 in x 11 ft 1-1/2 in ( originally for saint walpurgis , antwerp [ destroyed ] , now in antwerp cathedral ) the protestant north in the protestant countries , and especially in the newly-independent dutch republic , modern-day holland , the artistic climate changed radically in the aftermath of the reformation . two of the wealthiest sources of patronage—the monarchy and the church—were now gone . in their stead arose an increasingly prosperous middle class eager to express its status and its new sense of national pride through the purchase of art . by the middle of the 17th century , a new market had emerged to meet the artistic tastes of this class . the demand was now for smaller-scale paintings suitable for display in private homes . these paintings included religious subjects for private contemplation , as seen in rembrandt ’ s poignant paintings and prints of biblical narratives , as well as portraits documenting individual likenesses . judith leyster , self-portrait , c. 1630 , oil on canvas , 651 x 746 cm ( national gallery of art , washington ) but , the greatest change in the market was the dramatic increase in the popularity of landscapes , still-lifes , and scenes of everyday life—known as genre painting . indeed , the proliferation of these subjects as independent artistic genres was one of the 17th century ’ s most significant contributions to the history of western art . in all of these genres , artists revealed a keen interest in replicating observed reality—whether it be the light on the dutch landscape , the momentary expression on a face , or the varied textures and materials of the objects the dutch collected as they reaped the benefits of their expanding mercantile empire . these works demonstrated as much artistic virtuosity and physical immediacy as the grand decorations of the palaces and churches of catholic europe . in the context of european history , the period from c. 1585 to c. 1700/1730 is often called the baroque era . the word baroque derives from the portuguese and spanish words for a large , irregularly-shaped pearl—barroco and barrueco , respectively . eighteenth-century critics were the first to apply the term to the art of the 17th century . it was not a term of praise . to the eyes of these critics , who favored the restraint and order of neoclassicism , the works of bernini , borromini , and pietro da cortona appeared bizarre , absurd , even diseased—in other words , misshapen , like an imperfect pearl . francisco de zurbarán , saint francis of assisi according to pope nicholas v 's vision , c. 1640 , oil on canvas , 110.5 x 180.5 cm ( museum nacional d'art de catalunya , barcelona ) baroque—the word , the style , the period by the middle of the 19th century , the word baroque had lost its pejorative implications and was used to describe the ornate and complex qualities present in many examples of 17th-century art , music , and literature . eventually , the term came to designate the historical period as a whole . in the context of painting , for example , the stark realism of zurbaran ’ s altarpieces , the quiet intimacy of vermeer ’ s domestic interiors , and the restrained classicism of poussin ’ s landscapes are all baroque—now with a capital b to indicate the historical period—regardless of the absence of the stylistic traits originally associated with the term . scholars continue to debate the validity of this label , admitting the usefulness of having a label for this distinct historical period , while also acknowledging its limitations in characterizing the variety of artistic styles present in the 17th century . essay by dr. esperança camara additional resources baroque rome on the metropolitan museum of art 's heilbrunn timeline of art history annibale carracci on the metropolitan museum of art 's heilbrunn timeline of art history
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scholars continue to debate the validity of this label , admitting the usefulness of having a label for this distinct historical period , while also acknowledging its limitations in characterizing the variety of artistic styles present in the 17th century . essay by dr. esperança camara additional resources baroque rome on the metropolitan museum of art 's heilbrunn timeline of art history annibale carracci on the metropolitan museum of art 's heilbrunn timeline of art history
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would the painting styles present in baroque works carry over as an influence towards art in the future ?
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gian lorenzo bernini ; view to cathedra petri ( chair of st. peter ) , gilded bronze , gold , wood , stained glass ; 1647-53 ( apse of saint peter 's basilica , vatican city , rome ) . image credit : steven zucker , cc by-nc-sa 2.0 rome : from the whore of babylon to the resplendent bride of christ when martin luther tacked his 95 theses to the doors of wittenberg cathedral in 1517 protesting the catholic church ’ s corruption , he initiated a movement that would transform the religious , political , and artistic landscape of europe . for the next century , europe would be in turmoil as new political and religious boundaries were determined , often through bloody military conflicts . only in 1648 , with the signing of the treaty of westphalia , did the conflicts between protestants and catholics subside in continental europe . martin luther focused his critique on what he saw as the church ’ s greed and abuse of power . he called rome , the seat of papal power , “ the whore of babylon ” decked out in finery of expensive art , grand architecture , and sumptuous banquets . the church responded to the crisis in two ways : by internally addressing issues of corruption and by defending the doctrines rejected by the protestants . thus , while the first two decades of the 16th century were a period of lavish spending for the papacy , the middle decades were a period of austerity . as one visitor to rome noted in the 1560s , the entire city had become a convent . piety and asceticism ruled the day . by the end of the 16th century , the catholic church was once again feeling optimistic , even triumphant . it had emerged from the crisis with renewed vigor and clarity of purpose . shepherding the faithful—instructing them on catholic doctrines and inspiring virtuous behavior—took center stage . keen to rebuild rome ’ s reputation as a holy city , the papacy embarked on extensive building and decoration campaigns aimed at highlighting its ancient origins , its beliefs , and its divinely-sanctioned authority . in the eyes of faithful catholics , rome was not an unfaithful whore , but a pure bride , beautifully adorned for her union with her divine spouse . the art of persuasion : instruct , delight , move while the protestants harshly criticized the cult of images , the catholic church ardently embraced the religious power of art . the visual arts , the church argued , played a key role in guiding the faithful . they were certainly as important as the written and spoken word , and perhaps even more important since they were accessible to the learned and the unlearned alike . in order to be effective in its pastoral role , religious art had to be clear , persuasive , and powerful . not only did it have to instruct , it had to inspire . it had to move the faithful to feel the reality of christ ’ s sacrifice , the suffering of the martyrs , the visions of the saints . caravaggio , the crowning with thorns , 1602-04 , oil on canvas , 165.5 x 127 cm ( kunsthistorisches museum , vienna ) the church ’ s emphasis on art ’ s pastoral role prompted artists to experiment with new and more direct means of engaging the viewer . artists like caravaggio turned to a powerful and dramatic realism , accentuated by bold contrasts of light and dark , and tightly-cropped compositions that enhanced the physical and emotional immediacy of the depicted narrative . other artists , like annibale carracci—who also experimented with realism—ultimately settled on a more classical visual language , inspired by the vibrant palette , idealized forms , and balanced compositions of the high renaissance , see image above . still others , like giovanni battista gaulli , turned to daring feats of illusionism that blurred not only the boundaries between painting , sculpture , and architecture , but also those between the real and depicted worlds . in so doing , the divine was made physically present and palpable . whether through shocking realism , dynamic movement , or exuberant ornamentation , 17th-century art was meant to impress . it aimed to convince the viewer of the truth of its message by impacting the senses , awakening the emotions , and activating—even sharing—the viewer ’ s space . giovanni battista gaulli , also known as il baciccio , the triumph of the name of jesus , il , gesù ceiling fresco , 1672-1685 the catholic monarchs and their territories the monarchs of spain , portugal , and france also embraced the more ornate elements of 17th-century art to celebrate catholicism . in spain and its colonies , rulers invested vast resources on elaborate church facades , stunning , gold-covered chapels and tabernacles , and strikingly-realistic polychrome sculpture . in the spanish netherlands , where sacred art had suffered terribly as a result of the protestant iconoclasm—the destruction of art—civic and religious leaders prioritized the adornment of churches as the region reclaimed its catholic identity . refurnishing the altars of antwerp ’ s churches kept peter paul rubens ’ workshop busy for many years . europe ’ s monarchs also adopted this artistic vocabulary to proclaim their own power and status . louis xiv , for example , commissioned the splendid buildings and gardens of versailles as a visual expression of his divine right to rule . peter paul rubens , elevation of the cross , 1610 , oil on wood , 15 ft 1-7/8 in x 11 ft 1-1/2 in ( originally for saint walpurgis , antwerp [ destroyed ] , now in antwerp cathedral ) the protestant north in the protestant countries , and especially in the newly-independent dutch republic , modern-day holland , the artistic climate changed radically in the aftermath of the reformation . two of the wealthiest sources of patronage—the monarchy and the church—were now gone . in their stead arose an increasingly prosperous middle class eager to express its status and its new sense of national pride through the purchase of art . by the middle of the 17th century , a new market had emerged to meet the artistic tastes of this class . the demand was now for smaller-scale paintings suitable for display in private homes . these paintings included religious subjects for private contemplation , as seen in rembrandt ’ s poignant paintings and prints of biblical narratives , as well as portraits documenting individual likenesses . judith leyster , self-portrait , c. 1630 , oil on canvas , 651 x 746 cm ( national gallery of art , washington ) but , the greatest change in the market was the dramatic increase in the popularity of landscapes , still-lifes , and scenes of everyday life—known as genre painting . indeed , the proliferation of these subjects as independent artistic genres was one of the 17th century ’ s most significant contributions to the history of western art . in all of these genres , artists revealed a keen interest in replicating observed reality—whether it be the light on the dutch landscape , the momentary expression on a face , or the varied textures and materials of the objects the dutch collected as they reaped the benefits of their expanding mercantile empire . these works demonstrated as much artistic virtuosity and physical immediacy as the grand decorations of the palaces and churches of catholic europe . in the context of european history , the period from c. 1585 to c. 1700/1730 is often called the baroque era . the word baroque derives from the portuguese and spanish words for a large , irregularly-shaped pearl—barroco and barrueco , respectively . eighteenth-century critics were the first to apply the term to the art of the 17th century . it was not a term of praise . to the eyes of these critics , who favored the restraint and order of neoclassicism , the works of bernini , borromini , and pietro da cortona appeared bizarre , absurd , even diseased—in other words , misshapen , like an imperfect pearl . francisco de zurbarán , saint francis of assisi according to pope nicholas v 's vision , c. 1640 , oil on canvas , 110.5 x 180.5 cm ( museum nacional d'art de catalunya , barcelona ) baroque—the word , the style , the period by the middle of the 19th century , the word baroque had lost its pejorative implications and was used to describe the ornate and complex qualities present in many examples of 17th-century art , music , and literature . eventually , the term came to designate the historical period as a whole . in the context of painting , for example , the stark realism of zurbaran ’ s altarpieces , the quiet intimacy of vermeer ’ s domestic interiors , and the restrained classicism of poussin ’ s landscapes are all baroque—now with a capital b to indicate the historical period—regardless of the absence of the stylistic traits originally associated with the term . scholars continue to debate the validity of this label , admitting the usefulness of having a label for this distinct historical period , while also acknowledging its limitations in characterizing the variety of artistic styles present in the 17th century . essay by dr. esperança camara additional resources baroque rome on the metropolitan museum of art 's heilbrunn timeline of art history annibale carracci on the metropolitan museum of art 's heilbrunn timeline of art history
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these works demonstrated as much artistic virtuosity and physical immediacy as the grand decorations of the palaces and churches of catholic europe . in the context of european history , the period from c. 1585 to c. 1700/1730 is often called the baroque era . the word baroque derives from the portuguese and spanish words for a large , irregularly-shaped pearl—barroco and barrueco , respectively .
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and can people today recreate those paintings in the baroque period , especially considering new-found technology and cgi ?
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gian lorenzo bernini ; view to cathedra petri ( chair of st. peter ) , gilded bronze , gold , wood , stained glass ; 1647-53 ( apse of saint peter 's basilica , vatican city , rome ) . image credit : steven zucker , cc by-nc-sa 2.0 rome : from the whore of babylon to the resplendent bride of christ when martin luther tacked his 95 theses to the doors of wittenberg cathedral in 1517 protesting the catholic church ’ s corruption , he initiated a movement that would transform the religious , political , and artistic landscape of europe . for the next century , europe would be in turmoil as new political and religious boundaries were determined , often through bloody military conflicts . only in 1648 , with the signing of the treaty of westphalia , did the conflicts between protestants and catholics subside in continental europe . martin luther focused his critique on what he saw as the church ’ s greed and abuse of power . he called rome , the seat of papal power , “ the whore of babylon ” decked out in finery of expensive art , grand architecture , and sumptuous banquets . the church responded to the crisis in two ways : by internally addressing issues of corruption and by defending the doctrines rejected by the protestants . thus , while the first two decades of the 16th century were a period of lavish spending for the papacy , the middle decades were a period of austerity . as one visitor to rome noted in the 1560s , the entire city had become a convent . piety and asceticism ruled the day . by the end of the 16th century , the catholic church was once again feeling optimistic , even triumphant . it had emerged from the crisis with renewed vigor and clarity of purpose . shepherding the faithful—instructing them on catholic doctrines and inspiring virtuous behavior—took center stage . keen to rebuild rome ’ s reputation as a holy city , the papacy embarked on extensive building and decoration campaigns aimed at highlighting its ancient origins , its beliefs , and its divinely-sanctioned authority . in the eyes of faithful catholics , rome was not an unfaithful whore , but a pure bride , beautifully adorned for her union with her divine spouse . the art of persuasion : instruct , delight , move while the protestants harshly criticized the cult of images , the catholic church ardently embraced the religious power of art . the visual arts , the church argued , played a key role in guiding the faithful . they were certainly as important as the written and spoken word , and perhaps even more important since they were accessible to the learned and the unlearned alike . in order to be effective in its pastoral role , religious art had to be clear , persuasive , and powerful . not only did it have to instruct , it had to inspire . it had to move the faithful to feel the reality of christ ’ s sacrifice , the suffering of the martyrs , the visions of the saints . caravaggio , the crowning with thorns , 1602-04 , oil on canvas , 165.5 x 127 cm ( kunsthistorisches museum , vienna ) the church ’ s emphasis on art ’ s pastoral role prompted artists to experiment with new and more direct means of engaging the viewer . artists like caravaggio turned to a powerful and dramatic realism , accentuated by bold contrasts of light and dark , and tightly-cropped compositions that enhanced the physical and emotional immediacy of the depicted narrative . other artists , like annibale carracci—who also experimented with realism—ultimately settled on a more classical visual language , inspired by the vibrant palette , idealized forms , and balanced compositions of the high renaissance , see image above . still others , like giovanni battista gaulli , turned to daring feats of illusionism that blurred not only the boundaries between painting , sculpture , and architecture , but also those between the real and depicted worlds . in so doing , the divine was made physically present and palpable . whether through shocking realism , dynamic movement , or exuberant ornamentation , 17th-century art was meant to impress . it aimed to convince the viewer of the truth of its message by impacting the senses , awakening the emotions , and activating—even sharing—the viewer ’ s space . giovanni battista gaulli , also known as il baciccio , the triumph of the name of jesus , il , gesù ceiling fresco , 1672-1685 the catholic monarchs and their territories the monarchs of spain , portugal , and france also embraced the more ornate elements of 17th-century art to celebrate catholicism . in spain and its colonies , rulers invested vast resources on elaborate church facades , stunning , gold-covered chapels and tabernacles , and strikingly-realistic polychrome sculpture . in the spanish netherlands , where sacred art had suffered terribly as a result of the protestant iconoclasm—the destruction of art—civic and religious leaders prioritized the adornment of churches as the region reclaimed its catholic identity . refurnishing the altars of antwerp ’ s churches kept peter paul rubens ’ workshop busy for many years . europe ’ s monarchs also adopted this artistic vocabulary to proclaim their own power and status . louis xiv , for example , commissioned the splendid buildings and gardens of versailles as a visual expression of his divine right to rule . peter paul rubens , elevation of the cross , 1610 , oil on wood , 15 ft 1-7/8 in x 11 ft 1-1/2 in ( originally for saint walpurgis , antwerp [ destroyed ] , now in antwerp cathedral ) the protestant north in the protestant countries , and especially in the newly-independent dutch republic , modern-day holland , the artistic climate changed radically in the aftermath of the reformation . two of the wealthiest sources of patronage—the monarchy and the church—were now gone . in their stead arose an increasingly prosperous middle class eager to express its status and its new sense of national pride through the purchase of art . by the middle of the 17th century , a new market had emerged to meet the artistic tastes of this class . the demand was now for smaller-scale paintings suitable for display in private homes . these paintings included religious subjects for private contemplation , as seen in rembrandt ’ s poignant paintings and prints of biblical narratives , as well as portraits documenting individual likenesses . judith leyster , self-portrait , c. 1630 , oil on canvas , 651 x 746 cm ( national gallery of art , washington ) but , the greatest change in the market was the dramatic increase in the popularity of landscapes , still-lifes , and scenes of everyday life—known as genre painting . indeed , the proliferation of these subjects as independent artistic genres was one of the 17th century ’ s most significant contributions to the history of western art . in all of these genres , artists revealed a keen interest in replicating observed reality—whether it be the light on the dutch landscape , the momentary expression on a face , or the varied textures and materials of the objects the dutch collected as they reaped the benefits of their expanding mercantile empire . these works demonstrated as much artistic virtuosity and physical immediacy as the grand decorations of the palaces and churches of catholic europe . in the context of european history , the period from c. 1585 to c. 1700/1730 is often called the baroque era . the word baroque derives from the portuguese and spanish words for a large , irregularly-shaped pearl—barroco and barrueco , respectively . eighteenth-century critics were the first to apply the term to the art of the 17th century . it was not a term of praise . to the eyes of these critics , who favored the restraint and order of neoclassicism , the works of bernini , borromini , and pietro da cortona appeared bizarre , absurd , even diseased—in other words , misshapen , like an imperfect pearl . francisco de zurbarán , saint francis of assisi according to pope nicholas v 's vision , c. 1640 , oil on canvas , 110.5 x 180.5 cm ( museum nacional d'art de catalunya , barcelona ) baroque—the word , the style , the period by the middle of the 19th century , the word baroque had lost its pejorative implications and was used to describe the ornate and complex qualities present in many examples of 17th-century art , music , and literature . eventually , the term came to designate the historical period as a whole . in the context of painting , for example , the stark realism of zurbaran ’ s altarpieces , the quiet intimacy of vermeer ’ s domestic interiors , and the restrained classicism of poussin ’ s landscapes are all baroque—now with a capital b to indicate the historical period—regardless of the absence of the stylistic traits originally associated with the term . scholars continue to debate the validity of this label , admitting the usefulness of having a label for this distinct historical period , while also acknowledging its limitations in characterizing the variety of artistic styles present in the 17th century . essay by dr. esperança camara additional resources baroque rome on the metropolitan museum of art 's heilbrunn timeline of art history annibale carracci on the metropolitan museum of art 's heilbrunn timeline of art history
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in the context of european history , the period from c. 1585 to c. 1700/1730 is often called the baroque era . the word baroque derives from the portuguese and spanish words for a large , irregularly-shaped pearl—barroco and barrueco , respectively . eighteenth-century critics were the first to apply the term to the art of the 17th century .
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i have three questions ( and after i get off ka tonight i 'll go google them up ) , but i think the essay missed something critical as an introduction : first , what does the word `` baroque '' mean ?
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gian lorenzo bernini ; view to cathedra petri ( chair of st. peter ) , gilded bronze , gold , wood , stained glass ; 1647-53 ( apse of saint peter 's basilica , vatican city , rome ) . image credit : steven zucker , cc by-nc-sa 2.0 rome : from the whore of babylon to the resplendent bride of christ when martin luther tacked his 95 theses to the doors of wittenberg cathedral in 1517 protesting the catholic church ’ s corruption , he initiated a movement that would transform the religious , political , and artistic landscape of europe . for the next century , europe would be in turmoil as new political and religious boundaries were determined , often through bloody military conflicts . only in 1648 , with the signing of the treaty of westphalia , did the conflicts between protestants and catholics subside in continental europe . martin luther focused his critique on what he saw as the church ’ s greed and abuse of power . he called rome , the seat of papal power , “ the whore of babylon ” decked out in finery of expensive art , grand architecture , and sumptuous banquets . the church responded to the crisis in two ways : by internally addressing issues of corruption and by defending the doctrines rejected by the protestants . thus , while the first two decades of the 16th century were a period of lavish spending for the papacy , the middle decades were a period of austerity . as one visitor to rome noted in the 1560s , the entire city had become a convent . piety and asceticism ruled the day . by the end of the 16th century , the catholic church was once again feeling optimistic , even triumphant . it had emerged from the crisis with renewed vigor and clarity of purpose . shepherding the faithful—instructing them on catholic doctrines and inspiring virtuous behavior—took center stage . keen to rebuild rome ’ s reputation as a holy city , the papacy embarked on extensive building and decoration campaigns aimed at highlighting its ancient origins , its beliefs , and its divinely-sanctioned authority . in the eyes of faithful catholics , rome was not an unfaithful whore , but a pure bride , beautifully adorned for her union with her divine spouse . the art of persuasion : instruct , delight , move while the protestants harshly criticized the cult of images , the catholic church ardently embraced the religious power of art . the visual arts , the church argued , played a key role in guiding the faithful . they were certainly as important as the written and spoken word , and perhaps even more important since they were accessible to the learned and the unlearned alike . in order to be effective in its pastoral role , religious art had to be clear , persuasive , and powerful . not only did it have to instruct , it had to inspire . it had to move the faithful to feel the reality of christ ’ s sacrifice , the suffering of the martyrs , the visions of the saints . caravaggio , the crowning with thorns , 1602-04 , oil on canvas , 165.5 x 127 cm ( kunsthistorisches museum , vienna ) the church ’ s emphasis on art ’ s pastoral role prompted artists to experiment with new and more direct means of engaging the viewer . artists like caravaggio turned to a powerful and dramatic realism , accentuated by bold contrasts of light and dark , and tightly-cropped compositions that enhanced the physical and emotional immediacy of the depicted narrative . other artists , like annibale carracci—who also experimented with realism—ultimately settled on a more classical visual language , inspired by the vibrant palette , idealized forms , and balanced compositions of the high renaissance , see image above . still others , like giovanni battista gaulli , turned to daring feats of illusionism that blurred not only the boundaries between painting , sculpture , and architecture , but also those between the real and depicted worlds . in so doing , the divine was made physically present and palpable . whether through shocking realism , dynamic movement , or exuberant ornamentation , 17th-century art was meant to impress . it aimed to convince the viewer of the truth of its message by impacting the senses , awakening the emotions , and activating—even sharing—the viewer ’ s space . giovanni battista gaulli , also known as il baciccio , the triumph of the name of jesus , il , gesù ceiling fresco , 1672-1685 the catholic monarchs and their territories the monarchs of spain , portugal , and france also embraced the more ornate elements of 17th-century art to celebrate catholicism . in spain and its colonies , rulers invested vast resources on elaborate church facades , stunning , gold-covered chapels and tabernacles , and strikingly-realistic polychrome sculpture . in the spanish netherlands , where sacred art had suffered terribly as a result of the protestant iconoclasm—the destruction of art—civic and religious leaders prioritized the adornment of churches as the region reclaimed its catholic identity . refurnishing the altars of antwerp ’ s churches kept peter paul rubens ’ workshop busy for many years . europe ’ s monarchs also adopted this artistic vocabulary to proclaim their own power and status . louis xiv , for example , commissioned the splendid buildings and gardens of versailles as a visual expression of his divine right to rule . peter paul rubens , elevation of the cross , 1610 , oil on wood , 15 ft 1-7/8 in x 11 ft 1-1/2 in ( originally for saint walpurgis , antwerp [ destroyed ] , now in antwerp cathedral ) the protestant north in the protestant countries , and especially in the newly-independent dutch republic , modern-day holland , the artistic climate changed radically in the aftermath of the reformation . two of the wealthiest sources of patronage—the monarchy and the church—were now gone . in their stead arose an increasingly prosperous middle class eager to express its status and its new sense of national pride through the purchase of art . by the middle of the 17th century , a new market had emerged to meet the artistic tastes of this class . the demand was now for smaller-scale paintings suitable for display in private homes . these paintings included religious subjects for private contemplation , as seen in rembrandt ’ s poignant paintings and prints of biblical narratives , as well as portraits documenting individual likenesses . judith leyster , self-portrait , c. 1630 , oil on canvas , 651 x 746 cm ( national gallery of art , washington ) but , the greatest change in the market was the dramatic increase in the popularity of landscapes , still-lifes , and scenes of everyday life—known as genre painting . indeed , the proliferation of these subjects as independent artistic genres was one of the 17th century ’ s most significant contributions to the history of western art . in all of these genres , artists revealed a keen interest in replicating observed reality—whether it be the light on the dutch landscape , the momentary expression on a face , or the varied textures and materials of the objects the dutch collected as they reaped the benefits of their expanding mercantile empire . these works demonstrated as much artistic virtuosity and physical immediacy as the grand decorations of the palaces and churches of catholic europe . in the context of european history , the period from c. 1585 to c. 1700/1730 is often called the baroque era . the word baroque derives from the portuguese and spanish words for a large , irregularly-shaped pearl—barroco and barrueco , respectively . eighteenth-century critics were the first to apply the term to the art of the 17th century . it was not a term of praise . to the eyes of these critics , who favored the restraint and order of neoclassicism , the works of bernini , borromini , and pietro da cortona appeared bizarre , absurd , even diseased—in other words , misshapen , like an imperfect pearl . francisco de zurbarán , saint francis of assisi according to pope nicholas v 's vision , c. 1640 , oil on canvas , 110.5 x 180.5 cm ( museum nacional d'art de catalunya , barcelona ) baroque—the word , the style , the period by the middle of the 19th century , the word baroque had lost its pejorative implications and was used to describe the ornate and complex qualities present in many examples of 17th-century art , music , and literature . eventually , the term came to designate the historical period as a whole . in the context of painting , for example , the stark realism of zurbaran ’ s altarpieces , the quiet intimacy of vermeer ’ s domestic interiors , and the restrained classicism of poussin ’ s landscapes are all baroque—now with a capital b to indicate the historical period—regardless of the absence of the stylistic traits originally associated with the term . scholars continue to debate the validity of this label , admitting the usefulness of having a label for this distinct historical period , while also acknowledging its limitations in characterizing the variety of artistic styles present in the 17th century . essay by dr. esperança camara additional resources baroque rome on the metropolitan museum of art 's heilbrunn timeline of art history annibale carracci on the metropolitan museum of art 's heilbrunn timeline of art history
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these works demonstrated as much artistic virtuosity and physical immediacy as the grand decorations of the palaces and churches of catholic europe . in the context of european history , the period from c. 1585 to c. 1700/1730 is often called the baroque era . the word baroque derives from the portuguese and spanish words for a large , irregularly-shaped pearl—barroco and barrueco , respectively . eighteenth-century critics were the first to apply the term to the art of the 17th century .
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secondly , what centuries are considered `` baroque '' and what was the dividing line between the renaissance and the baroque ?
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gian lorenzo bernini ; view to cathedra petri ( chair of st. peter ) , gilded bronze , gold , wood , stained glass ; 1647-53 ( apse of saint peter 's basilica , vatican city , rome ) . image credit : steven zucker , cc by-nc-sa 2.0 rome : from the whore of babylon to the resplendent bride of christ when martin luther tacked his 95 theses to the doors of wittenberg cathedral in 1517 protesting the catholic church ’ s corruption , he initiated a movement that would transform the religious , political , and artistic landscape of europe . for the next century , europe would be in turmoil as new political and religious boundaries were determined , often through bloody military conflicts . only in 1648 , with the signing of the treaty of westphalia , did the conflicts between protestants and catholics subside in continental europe . martin luther focused his critique on what he saw as the church ’ s greed and abuse of power . he called rome , the seat of papal power , “ the whore of babylon ” decked out in finery of expensive art , grand architecture , and sumptuous banquets . the church responded to the crisis in two ways : by internally addressing issues of corruption and by defending the doctrines rejected by the protestants . thus , while the first two decades of the 16th century were a period of lavish spending for the papacy , the middle decades were a period of austerity . as one visitor to rome noted in the 1560s , the entire city had become a convent . piety and asceticism ruled the day . by the end of the 16th century , the catholic church was once again feeling optimistic , even triumphant . it had emerged from the crisis with renewed vigor and clarity of purpose . shepherding the faithful—instructing them on catholic doctrines and inspiring virtuous behavior—took center stage . keen to rebuild rome ’ s reputation as a holy city , the papacy embarked on extensive building and decoration campaigns aimed at highlighting its ancient origins , its beliefs , and its divinely-sanctioned authority . in the eyes of faithful catholics , rome was not an unfaithful whore , but a pure bride , beautifully adorned for her union with her divine spouse . the art of persuasion : instruct , delight , move while the protestants harshly criticized the cult of images , the catholic church ardently embraced the religious power of art . the visual arts , the church argued , played a key role in guiding the faithful . they were certainly as important as the written and spoken word , and perhaps even more important since they were accessible to the learned and the unlearned alike . in order to be effective in its pastoral role , religious art had to be clear , persuasive , and powerful . not only did it have to instruct , it had to inspire . it had to move the faithful to feel the reality of christ ’ s sacrifice , the suffering of the martyrs , the visions of the saints . caravaggio , the crowning with thorns , 1602-04 , oil on canvas , 165.5 x 127 cm ( kunsthistorisches museum , vienna ) the church ’ s emphasis on art ’ s pastoral role prompted artists to experiment with new and more direct means of engaging the viewer . artists like caravaggio turned to a powerful and dramatic realism , accentuated by bold contrasts of light and dark , and tightly-cropped compositions that enhanced the physical and emotional immediacy of the depicted narrative . other artists , like annibale carracci—who also experimented with realism—ultimately settled on a more classical visual language , inspired by the vibrant palette , idealized forms , and balanced compositions of the high renaissance , see image above . still others , like giovanni battista gaulli , turned to daring feats of illusionism that blurred not only the boundaries between painting , sculpture , and architecture , but also those between the real and depicted worlds . in so doing , the divine was made physically present and palpable . whether through shocking realism , dynamic movement , or exuberant ornamentation , 17th-century art was meant to impress . it aimed to convince the viewer of the truth of its message by impacting the senses , awakening the emotions , and activating—even sharing—the viewer ’ s space . giovanni battista gaulli , also known as il baciccio , the triumph of the name of jesus , il , gesù ceiling fresco , 1672-1685 the catholic monarchs and their territories the monarchs of spain , portugal , and france also embraced the more ornate elements of 17th-century art to celebrate catholicism . in spain and its colonies , rulers invested vast resources on elaborate church facades , stunning , gold-covered chapels and tabernacles , and strikingly-realistic polychrome sculpture . in the spanish netherlands , where sacred art had suffered terribly as a result of the protestant iconoclasm—the destruction of art—civic and religious leaders prioritized the adornment of churches as the region reclaimed its catholic identity . refurnishing the altars of antwerp ’ s churches kept peter paul rubens ’ workshop busy for many years . europe ’ s monarchs also adopted this artistic vocabulary to proclaim their own power and status . louis xiv , for example , commissioned the splendid buildings and gardens of versailles as a visual expression of his divine right to rule . peter paul rubens , elevation of the cross , 1610 , oil on wood , 15 ft 1-7/8 in x 11 ft 1-1/2 in ( originally for saint walpurgis , antwerp [ destroyed ] , now in antwerp cathedral ) the protestant north in the protestant countries , and especially in the newly-independent dutch republic , modern-day holland , the artistic climate changed radically in the aftermath of the reformation . two of the wealthiest sources of patronage—the monarchy and the church—were now gone . in their stead arose an increasingly prosperous middle class eager to express its status and its new sense of national pride through the purchase of art . by the middle of the 17th century , a new market had emerged to meet the artistic tastes of this class . the demand was now for smaller-scale paintings suitable for display in private homes . these paintings included religious subjects for private contemplation , as seen in rembrandt ’ s poignant paintings and prints of biblical narratives , as well as portraits documenting individual likenesses . judith leyster , self-portrait , c. 1630 , oil on canvas , 651 x 746 cm ( national gallery of art , washington ) but , the greatest change in the market was the dramatic increase in the popularity of landscapes , still-lifes , and scenes of everyday life—known as genre painting . indeed , the proliferation of these subjects as independent artistic genres was one of the 17th century ’ s most significant contributions to the history of western art . in all of these genres , artists revealed a keen interest in replicating observed reality—whether it be the light on the dutch landscape , the momentary expression on a face , or the varied textures and materials of the objects the dutch collected as they reaped the benefits of their expanding mercantile empire . these works demonstrated as much artistic virtuosity and physical immediacy as the grand decorations of the palaces and churches of catholic europe . in the context of european history , the period from c. 1585 to c. 1700/1730 is often called the baroque era . the word baroque derives from the portuguese and spanish words for a large , irregularly-shaped pearl—barroco and barrueco , respectively . eighteenth-century critics were the first to apply the term to the art of the 17th century . it was not a term of praise . to the eyes of these critics , who favored the restraint and order of neoclassicism , the works of bernini , borromini , and pietro da cortona appeared bizarre , absurd , even diseased—in other words , misshapen , like an imperfect pearl . francisco de zurbarán , saint francis of assisi according to pope nicholas v 's vision , c. 1640 , oil on canvas , 110.5 x 180.5 cm ( museum nacional d'art de catalunya , barcelona ) baroque—the word , the style , the period by the middle of the 19th century , the word baroque had lost its pejorative implications and was used to describe the ornate and complex qualities present in many examples of 17th-century art , music , and literature . eventually , the term came to designate the historical period as a whole . in the context of painting , for example , the stark realism of zurbaran ’ s altarpieces , the quiet intimacy of vermeer ’ s domestic interiors , and the restrained classicism of poussin ’ s landscapes are all baroque—now with a capital b to indicate the historical period—regardless of the absence of the stylistic traits originally associated with the term . scholars continue to debate the validity of this label , admitting the usefulness of having a label for this distinct historical period , while also acknowledging its limitations in characterizing the variety of artistic styles present in the 17th century . essay by dr. esperança camara additional resources baroque rome on the metropolitan museum of art 's heilbrunn timeline of art history annibale carracci on the metropolitan museum of art 's heilbrunn timeline of art history
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scholars continue to debate the validity of this label , admitting the usefulness of having a label for this distinct historical period , while also acknowledging its limitations in characterizing the variety of artistic styles present in the 17th century . essay by dr. esperança camara additional resources baroque rome on the metropolitan museum of art 's heilbrunn timeline of art history annibale carracci on the metropolitan museum of art 's heilbrunn timeline of art history
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finally , when was the term `` baroque '' first used as a context for art ?
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gian lorenzo bernini ; view to cathedra petri ( chair of st. peter ) , gilded bronze , gold , wood , stained glass ; 1647-53 ( apse of saint peter 's basilica , vatican city , rome ) . image credit : steven zucker , cc by-nc-sa 2.0 rome : from the whore of babylon to the resplendent bride of christ when martin luther tacked his 95 theses to the doors of wittenberg cathedral in 1517 protesting the catholic church ’ s corruption , he initiated a movement that would transform the religious , political , and artistic landscape of europe . for the next century , europe would be in turmoil as new political and religious boundaries were determined , often through bloody military conflicts . only in 1648 , with the signing of the treaty of westphalia , did the conflicts between protestants and catholics subside in continental europe . martin luther focused his critique on what he saw as the church ’ s greed and abuse of power . he called rome , the seat of papal power , “ the whore of babylon ” decked out in finery of expensive art , grand architecture , and sumptuous banquets . the church responded to the crisis in two ways : by internally addressing issues of corruption and by defending the doctrines rejected by the protestants . thus , while the first two decades of the 16th century were a period of lavish spending for the papacy , the middle decades were a period of austerity . as one visitor to rome noted in the 1560s , the entire city had become a convent . piety and asceticism ruled the day . by the end of the 16th century , the catholic church was once again feeling optimistic , even triumphant . it had emerged from the crisis with renewed vigor and clarity of purpose . shepherding the faithful—instructing them on catholic doctrines and inspiring virtuous behavior—took center stage . keen to rebuild rome ’ s reputation as a holy city , the papacy embarked on extensive building and decoration campaigns aimed at highlighting its ancient origins , its beliefs , and its divinely-sanctioned authority . in the eyes of faithful catholics , rome was not an unfaithful whore , but a pure bride , beautifully adorned for her union with her divine spouse . the art of persuasion : instruct , delight , move while the protestants harshly criticized the cult of images , the catholic church ardently embraced the religious power of art . the visual arts , the church argued , played a key role in guiding the faithful . they were certainly as important as the written and spoken word , and perhaps even more important since they were accessible to the learned and the unlearned alike . in order to be effective in its pastoral role , religious art had to be clear , persuasive , and powerful . not only did it have to instruct , it had to inspire . it had to move the faithful to feel the reality of christ ’ s sacrifice , the suffering of the martyrs , the visions of the saints . caravaggio , the crowning with thorns , 1602-04 , oil on canvas , 165.5 x 127 cm ( kunsthistorisches museum , vienna ) the church ’ s emphasis on art ’ s pastoral role prompted artists to experiment with new and more direct means of engaging the viewer . artists like caravaggio turned to a powerful and dramatic realism , accentuated by bold contrasts of light and dark , and tightly-cropped compositions that enhanced the physical and emotional immediacy of the depicted narrative . other artists , like annibale carracci—who also experimented with realism—ultimately settled on a more classical visual language , inspired by the vibrant palette , idealized forms , and balanced compositions of the high renaissance , see image above . still others , like giovanni battista gaulli , turned to daring feats of illusionism that blurred not only the boundaries between painting , sculpture , and architecture , but also those between the real and depicted worlds . in so doing , the divine was made physically present and palpable . whether through shocking realism , dynamic movement , or exuberant ornamentation , 17th-century art was meant to impress . it aimed to convince the viewer of the truth of its message by impacting the senses , awakening the emotions , and activating—even sharing—the viewer ’ s space . giovanni battista gaulli , also known as il baciccio , the triumph of the name of jesus , il , gesù ceiling fresco , 1672-1685 the catholic monarchs and their territories the monarchs of spain , portugal , and france also embraced the more ornate elements of 17th-century art to celebrate catholicism . in spain and its colonies , rulers invested vast resources on elaborate church facades , stunning , gold-covered chapels and tabernacles , and strikingly-realistic polychrome sculpture . in the spanish netherlands , where sacred art had suffered terribly as a result of the protestant iconoclasm—the destruction of art—civic and religious leaders prioritized the adornment of churches as the region reclaimed its catholic identity . refurnishing the altars of antwerp ’ s churches kept peter paul rubens ’ workshop busy for many years . europe ’ s monarchs also adopted this artistic vocabulary to proclaim their own power and status . louis xiv , for example , commissioned the splendid buildings and gardens of versailles as a visual expression of his divine right to rule . peter paul rubens , elevation of the cross , 1610 , oil on wood , 15 ft 1-7/8 in x 11 ft 1-1/2 in ( originally for saint walpurgis , antwerp [ destroyed ] , now in antwerp cathedral ) the protestant north in the protestant countries , and especially in the newly-independent dutch republic , modern-day holland , the artistic climate changed radically in the aftermath of the reformation . two of the wealthiest sources of patronage—the monarchy and the church—were now gone . in their stead arose an increasingly prosperous middle class eager to express its status and its new sense of national pride through the purchase of art . by the middle of the 17th century , a new market had emerged to meet the artistic tastes of this class . the demand was now for smaller-scale paintings suitable for display in private homes . these paintings included religious subjects for private contemplation , as seen in rembrandt ’ s poignant paintings and prints of biblical narratives , as well as portraits documenting individual likenesses . judith leyster , self-portrait , c. 1630 , oil on canvas , 651 x 746 cm ( national gallery of art , washington ) but , the greatest change in the market was the dramatic increase in the popularity of landscapes , still-lifes , and scenes of everyday life—known as genre painting . indeed , the proliferation of these subjects as independent artistic genres was one of the 17th century ’ s most significant contributions to the history of western art . in all of these genres , artists revealed a keen interest in replicating observed reality—whether it be the light on the dutch landscape , the momentary expression on a face , or the varied textures and materials of the objects the dutch collected as they reaped the benefits of their expanding mercantile empire . these works demonstrated as much artistic virtuosity and physical immediacy as the grand decorations of the palaces and churches of catholic europe . in the context of european history , the period from c. 1585 to c. 1700/1730 is often called the baroque era . the word baroque derives from the portuguese and spanish words for a large , irregularly-shaped pearl—barroco and barrueco , respectively . eighteenth-century critics were the first to apply the term to the art of the 17th century . it was not a term of praise . to the eyes of these critics , who favored the restraint and order of neoclassicism , the works of bernini , borromini , and pietro da cortona appeared bizarre , absurd , even diseased—in other words , misshapen , like an imperfect pearl . francisco de zurbarán , saint francis of assisi according to pope nicholas v 's vision , c. 1640 , oil on canvas , 110.5 x 180.5 cm ( museum nacional d'art de catalunya , barcelona ) baroque—the word , the style , the period by the middle of the 19th century , the word baroque had lost its pejorative implications and was used to describe the ornate and complex qualities present in many examples of 17th-century art , music , and literature . eventually , the term came to designate the historical period as a whole . in the context of painting , for example , the stark realism of zurbaran ’ s altarpieces , the quiet intimacy of vermeer ’ s domestic interiors , and the restrained classicism of poussin ’ s landscapes are all baroque—now with a capital b to indicate the historical period—regardless of the absence of the stylistic traits originally associated with the term . scholars continue to debate the validity of this label , admitting the usefulness of having a label for this distinct historical period , while also acknowledging its limitations in characterizing the variety of artistic styles present in the 17th century . essay by dr. esperança camara additional resources baroque rome on the metropolitan museum of art 's heilbrunn timeline of art history annibale carracci on the metropolitan museum of art 's heilbrunn timeline of art history
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refurnishing the altars of antwerp ’ s churches kept peter paul rubens ’ workshop busy for many years . europe ’ s monarchs also adopted this artistic vocabulary to proclaim their own power and status . louis xiv , for example , commissioned the splendid buildings and gardens of versailles as a visual expression of his divine right to rule .
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what happened to the monarchy 's power after the reformation ?
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gian lorenzo bernini ; view to cathedra petri ( chair of st. peter ) , gilded bronze , gold , wood , stained glass ; 1647-53 ( apse of saint peter 's basilica , vatican city , rome ) . image credit : steven zucker , cc by-nc-sa 2.0 rome : from the whore of babylon to the resplendent bride of christ when martin luther tacked his 95 theses to the doors of wittenberg cathedral in 1517 protesting the catholic church ’ s corruption , he initiated a movement that would transform the religious , political , and artistic landscape of europe . for the next century , europe would be in turmoil as new political and religious boundaries were determined , often through bloody military conflicts . only in 1648 , with the signing of the treaty of westphalia , did the conflicts between protestants and catholics subside in continental europe . martin luther focused his critique on what he saw as the church ’ s greed and abuse of power . he called rome , the seat of papal power , “ the whore of babylon ” decked out in finery of expensive art , grand architecture , and sumptuous banquets . the church responded to the crisis in two ways : by internally addressing issues of corruption and by defending the doctrines rejected by the protestants . thus , while the first two decades of the 16th century were a period of lavish spending for the papacy , the middle decades were a period of austerity . as one visitor to rome noted in the 1560s , the entire city had become a convent . piety and asceticism ruled the day . by the end of the 16th century , the catholic church was once again feeling optimistic , even triumphant . it had emerged from the crisis with renewed vigor and clarity of purpose . shepherding the faithful—instructing them on catholic doctrines and inspiring virtuous behavior—took center stage . keen to rebuild rome ’ s reputation as a holy city , the papacy embarked on extensive building and decoration campaigns aimed at highlighting its ancient origins , its beliefs , and its divinely-sanctioned authority . in the eyes of faithful catholics , rome was not an unfaithful whore , but a pure bride , beautifully adorned for her union with her divine spouse . the art of persuasion : instruct , delight , move while the protestants harshly criticized the cult of images , the catholic church ardently embraced the religious power of art . the visual arts , the church argued , played a key role in guiding the faithful . they were certainly as important as the written and spoken word , and perhaps even more important since they were accessible to the learned and the unlearned alike . in order to be effective in its pastoral role , religious art had to be clear , persuasive , and powerful . not only did it have to instruct , it had to inspire . it had to move the faithful to feel the reality of christ ’ s sacrifice , the suffering of the martyrs , the visions of the saints . caravaggio , the crowning with thorns , 1602-04 , oil on canvas , 165.5 x 127 cm ( kunsthistorisches museum , vienna ) the church ’ s emphasis on art ’ s pastoral role prompted artists to experiment with new and more direct means of engaging the viewer . artists like caravaggio turned to a powerful and dramatic realism , accentuated by bold contrasts of light and dark , and tightly-cropped compositions that enhanced the physical and emotional immediacy of the depicted narrative . other artists , like annibale carracci—who also experimented with realism—ultimately settled on a more classical visual language , inspired by the vibrant palette , idealized forms , and balanced compositions of the high renaissance , see image above . still others , like giovanni battista gaulli , turned to daring feats of illusionism that blurred not only the boundaries between painting , sculpture , and architecture , but also those between the real and depicted worlds . in so doing , the divine was made physically present and palpable . whether through shocking realism , dynamic movement , or exuberant ornamentation , 17th-century art was meant to impress . it aimed to convince the viewer of the truth of its message by impacting the senses , awakening the emotions , and activating—even sharing—the viewer ’ s space . giovanni battista gaulli , also known as il baciccio , the triumph of the name of jesus , il , gesù ceiling fresco , 1672-1685 the catholic monarchs and their territories the monarchs of spain , portugal , and france also embraced the more ornate elements of 17th-century art to celebrate catholicism . in spain and its colonies , rulers invested vast resources on elaborate church facades , stunning , gold-covered chapels and tabernacles , and strikingly-realistic polychrome sculpture . in the spanish netherlands , where sacred art had suffered terribly as a result of the protestant iconoclasm—the destruction of art—civic and religious leaders prioritized the adornment of churches as the region reclaimed its catholic identity . refurnishing the altars of antwerp ’ s churches kept peter paul rubens ’ workshop busy for many years . europe ’ s monarchs also adopted this artistic vocabulary to proclaim their own power and status . louis xiv , for example , commissioned the splendid buildings and gardens of versailles as a visual expression of his divine right to rule . peter paul rubens , elevation of the cross , 1610 , oil on wood , 15 ft 1-7/8 in x 11 ft 1-1/2 in ( originally for saint walpurgis , antwerp [ destroyed ] , now in antwerp cathedral ) the protestant north in the protestant countries , and especially in the newly-independent dutch republic , modern-day holland , the artistic climate changed radically in the aftermath of the reformation . two of the wealthiest sources of patronage—the monarchy and the church—were now gone . in their stead arose an increasingly prosperous middle class eager to express its status and its new sense of national pride through the purchase of art . by the middle of the 17th century , a new market had emerged to meet the artistic tastes of this class . the demand was now for smaller-scale paintings suitable for display in private homes . these paintings included religious subjects for private contemplation , as seen in rembrandt ’ s poignant paintings and prints of biblical narratives , as well as portraits documenting individual likenesses . judith leyster , self-portrait , c. 1630 , oil on canvas , 651 x 746 cm ( national gallery of art , washington ) but , the greatest change in the market was the dramatic increase in the popularity of landscapes , still-lifes , and scenes of everyday life—known as genre painting . indeed , the proliferation of these subjects as independent artistic genres was one of the 17th century ’ s most significant contributions to the history of western art . in all of these genres , artists revealed a keen interest in replicating observed reality—whether it be the light on the dutch landscape , the momentary expression on a face , or the varied textures and materials of the objects the dutch collected as they reaped the benefits of their expanding mercantile empire . these works demonstrated as much artistic virtuosity and physical immediacy as the grand decorations of the palaces and churches of catholic europe . in the context of european history , the period from c. 1585 to c. 1700/1730 is often called the baroque era . the word baroque derives from the portuguese and spanish words for a large , irregularly-shaped pearl—barroco and barrueco , respectively . eighteenth-century critics were the first to apply the term to the art of the 17th century . it was not a term of praise . to the eyes of these critics , who favored the restraint and order of neoclassicism , the works of bernini , borromini , and pietro da cortona appeared bizarre , absurd , even diseased—in other words , misshapen , like an imperfect pearl . francisco de zurbarán , saint francis of assisi according to pope nicholas v 's vision , c. 1640 , oil on canvas , 110.5 x 180.5 cm ( museum nacional d'art de catalunya , barcelona ) baroque—the word , the style , the period by the middle of the 19th century , the word baroque had lost its pejorative implications and was used to describe the ornate and complex qualities present in many examples of 17th-century art , music , and literature . eventually , the term came to designate the historical period as a whole . in the context of painting , for example , the stark realism of zurbaran ’ s altarpieces , the quiet intimacy of vermeer ’ s domestic interiors , and the restrained classicism of poussin ’ s landscapes are all baroque—now with a capital b to indicate the historical period—regardless of the absence of the stylistic traits originally associated with the term . scholars continue to debate the validity of this label , admitting the usefulness of having a label for this distinct historical period , while also acknowledging its limitations in characterizing the variety of artistic styles present in the 17th century . essay by dr. esperança camara additional resources baroque rome on the metropolitan museum of art 's heilbrunn timeline of art history annibale carracci on the metropolitan museum of art 's heilbrunn timeline of art history
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these works demonstrated as much artistic virtuosity and physical immediacy as the grand decorations of the palaces and churches of catholic europe . in the context of european history , the period from c. 1585 to c. 1700/1730 is often called the baroque era . the word baroque derives from the portuguese and spanish words for a large , irregularly-shaped pearl—barroco and barrueco , respectively .
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how many countries had changed in the baroque era ?
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death . but have you ever wondered why that ’ s the case , or what exactly your body does with all that oxygen ? as it turns out , the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation , the final stage of cellular respiration . oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp . so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis . without enough atp , cells can ’ t carry out the reactions they need to function , and , after a long enough period of time , may even die . in this article , we 'll examine oxidative phosphorylation in depth , seeing how it provides most of the ready chemical energy ( atp ) used by the cells in your body . overview : oxidative phosphorylation the electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria . electrons are passed from one member of the transport chain to another in a series of redox reactions . energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ . reduced electron carriers ( nadh and fadh $ _2 $ ) from other steps of cellular respiration transfer their electrons to molecules near the beginning of the transport chain . in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy . some of the energy is used to pump h $ ^+ $ ions , moving them out of the matrix and into the intermembrane space . this pumping establishes an electrochemical gradient . splitting of oxygen to form water . at the end of the electron transport chain , electrons are transferred to molecular oxygen , which splits in half and takes up h $ ^+ $ to form water . gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane . as the electrons travel through the chain , they go from a higher to a lower energy level , moving from less electron-hungry to more electron-hungry molecules . energy is released in these “ downhill ” electron transfers , and several of the protein complexes use the released energy to pump protons from the mitochondrial matrix to the intermembrane space , forming a proton gradient . all of the electrons that enter the transport chain come from nadh and fadh $ _2 $ molecules produced during earlier stages of cellular respiration : glycolysis , pyruvate oxidation , and the citric acid cycle . nadh is very good at donating electrons in redox reactions ( that is , its electrons are at a high energy level ) , so it can transfer its electrons directly to complex i , turning back into nad $ ^+ $ . as electrons move through complex i in a series of redox reactions , energy is released , and the complex uses this energy to pump protons from the matrix into the intermembrane space . fadh $ _2 $ is not as good at donating electrons as nadh ( that is , its electrons are at a lower energy level ) , so it can not transfer its electrons to complex i . instead , it feeds them into the transport chain through complex ii , which does not pump protons across the membrane . because of this `` bypass , '' each fadh $ _2 $ molecule causes fewer protons to be pumped ( and contributes less to the proton gradient ) than an nadh . beyond the first two complexes , electrons from nadh and fadh $ _2 $ travel exactly the same route . both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water . four electrons are required to reduce each molecule of o $ _2 $ , and two water molecules are formed in the process . overall , what does the electron transport chain do for the cell ? it has two important functions : regenerates electron carriers . nadh and fadh $ _2 $ pass their electrons to the electron transport chain , turning back into nad $ ^+ $ and fad . this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix . this gradient represents a stored form of energy , and , as we ’ ll see , it can be used to make atp . chemiosmosis complexes i , iii , and iv of the electron transport chain are proton pumps . as electrons move energetically downhill , the complexes capture the released energy and use it to pump h $ ^+ $ ions from the matrix to the intermembrane space . this pumping forms an electrochemical gradient across the inner mitochondrial membrane . the gradient is sometimes called the proton-motive force , and you can think of it as a form of stored energy , kind of like a battery . like many other ions , protons ca n't pass directly through the phospholipid bilayer of the membrane because its core is too hydrophobic . instead , h $ ^+ $ ions can move down their concentration gradient only with the help of channel proteins that form hydrophilic tunnels across the membrane . in the inner mitochondrial membrane , h $ ^+ $ ions have just one channel available : a membrane-spanning protein known as atp synthase . conceptually , atp synthase is a lot like a turbine in a hydroelectric power plant . instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis . more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis . what would happen to the energy stored in the proton gradient if it were n't used to synthesize atp or do other cellular work ? it would be released as heat , and interestingly enough , some types of cells deliberately use the proton gradient for heat generation rather than atp synthesis . this might seem wasteful , but it 's an important strategy for animals that need to keep warm . for instance , hibernating mammals ( such as bears ) have specialized cells known as brown fat cells . in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers . however , most current sources estimate that the maximum atp yield for a molecule of glucose is around 30-32 atp $ ^ { 2,3,4 } $ . this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation . based on a lot of experimental work , it appears that four h $ ^+ $ ions must flow back into the matrix through atp synthase to power the synthesis of one atp molecule . when electrons from nadh move through the transport chain , about 10 h $ ^+ $ ions are pumped from the matrix to the intermembrane space , so each nadh yields about 2.5 atp . electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i . instead , it must hand its electrons off to a molecular “ shuttle system ” that delivers them , through a series of steps , to the electron transport chain . some cells of your body have a shuttle system that delivers electrons to the transport chain via fadh $ _2 $ . in this case , only 3 atp are produced for the two nadh of glycolysis . other cells of your body have a shuttle system that delivers the electrons via nadh , resulting in the production of 5 atp . in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced . cellular respiration is a nexus for many different metabolic pathways in the cell , forming a network that ’ s larger than the glucose breakdown pathways alone . self-check questions
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oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp .
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how does the nadh from glycolisys gets into the matrix so its electron could be used ?
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death . but have you ever wondered why that ’ s the case , or what exactly your body does with all that oxygen ? as it turns out , the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation , the final stage of cellular respiration . oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp . so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis . without enough atp , cells can ’ t carry out the reactions they need to function , and , after a long enough period of time , may even die . in this article , we 'll examine oxidative phosphorylation in depth , seeing how it provides most of the ready chemical energy ( atp ) used by the cells in your body . overview : oxidative phosphorylation the electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria . electrons are passed from one member of the transport chain to another in a series of redox reactions . energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ . reduced electron carriers ( nadh and fadh $ _2 $ ) from other steps of cellular respiration transfer their electrons to molecules near the beginning of the transport chain . in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy . some of the energy is used to pump h $ ^+ $ ions , moving them out of the matrix and into the intermembrane space . this pumping establishes an electrochemical gradient . splitting of oxygen to form water . at the end of the electron transport chain , electrons are transferred to molecular oxygen , which splits in half and takes up h $ ^+ $ to form water . gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane . as the electrons travel through the chain , they go from a higher to a lower energy level , moving from less electron-hungry to more electron-hungry molecules . energy is released in these “ downhill ” electron transfers , and several of the protein complexes use the released energy to pump protons from the mitochondrial matrix to the intermembrane space , forming a proton gradient . all of the electrons that enter the transport chain come from nadh and fadh $ _2 $ molecules produced during earlier stages of cellular respiration : glycolysis , pyruvate oxidation , and the citric acid cycle . nadh is very good at donating electrons in redox reactions ( that is , its electrons are at a high energy level ) , so it can transfer its electrons directly to complex i , turning back into nad $ ^+ $ . as electrons move through complex i in a series of redox reactions , energy is released , and the complex uses this energy to pump protons from the matrix into the intermembrane space . fadh $ _2 $ is not as good at donating electrons as nadh ( that is , its electrons are at a lower energy level ) , so it can not transfer its electrons to complex i . instead , it feeds them into the transport chain through complex ii , which does not pump protons across the membrane . because of this `` bypass , '' each fadh $ _2 $ molecule causes fewer protons to be pumped ( and contributes less to the proton gradient ) than an nadh . beyond the first two complexes , electrons from nadh and fadh $ _2 $ travel exactly the same route . both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water . four electrons are required to reduce each molecule of o $ _2 $ , and two water molecules are formed in the process . overall , what does the electron transport chain do for the cell ? it has two important functions : regenerates electron carriers . nadh and fadh $ _2 $ pass their electrons to the electron transport chain , turning back into nad $ ^+ $ and fad . this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix . this gradient represents a stored form of energy , and , as we ’ ll see , it can be used to make atp . chemiosmosis complexes i , iii , and iv of the electron transport chain are proton pumps . as electrons move energetically downhill , the complexes capture the released energy and use it to pump h $ ^+ $ ions from the matrix to the intermembrane space . this pumping forms an electrochemical gradient across the inner mitochondrial membrane . the gradient is sometimes called the proton-motive force , and you can think of it as a form of stored energy , kind of like a battery . like many other ions , protons ca n't pass directly through the phospholipid bilayer of the membrane because its core is too hydrophobic . instead , h $ ^+ $ ions can move down their concentration gradient only with the help of channel proteins that form hydrophilic tunnels across the membrane . in the inner mitochondrial membrane , h $ ^+ $ ions have just one channel available : a membrane-spanning protein known as atp synthase . conceptually , atp synthase is a lot like a turbine in a hydroelectric power plant . instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis . more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis . what would happen to the energy stored in the proton gradient if it were n't used to synthesize atp or do other cellular work ? it would be released as heat , and interestingly enough , some types of cells deliberately use the proton gradient for heat generation rather than atp synthesis . this might seem wasteful , but it 's an important strategy for animals that need to keep warm . for instance , hibernating mammals ( such as bears ) have specialized cells known as brown fat cells . in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers . however , most current sources estimate that the maximum atp yield for a molecule of glucose is around 30-32 atp $ ^ { 2,3,4 } $ . this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation . based on a lot of experimental work , it appears that four h $ ^+ $ ions must flow back into the matrix through atp synthase to power the synthesis of one atp molecule . when electrons from nadh move through the transport chain , about 10 h $ ^+ $ ions are pumped from the matrix to the intermembrane space , so each nadh yields about 2.5 atp . electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i . instead , it must hand its electrons off to a molecular “ shuttle system ” that delivers them , through a series of steps , to the electron transport chain . some cells of your body have a shuttle system that delivers electrons to the transport chain via fadh $ _2 $ . in this case , only 3 atp are produced for the two nadh of glycolysis . other cells of your body have a shuttle system that delivers the electrons via nadh , resulting in the production of 5 atp . in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced . cellular respiration is a nexus for many different metabolic pathways in the cell , forming a network that ’ s larger than the glucose breakdown pathways alone . self-check questions
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in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced .
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what does this mean for your table on the 'breakdown of one molecule of glucose ' ?
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death . but have you ever wondered why that ’ s the case , or what exactly your body does with all that oxygen ? as it turns out , the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation , the final stage of cellular respiration . oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp . so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis . without enough atp , cells can ’ t carry out the reactions they need to function , and , after a long enough period of time , may even die . in this article , we 'll examine oxidative phosphorylation in depth , seeing how it provides most of the ready chemical energy ( atp ) used by the cells in your body . overview : oxidative phosphorylation the electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria . electrons are passed from one member of the transport chain to another in a series of redox reactions . energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ . reduced electron carriers ( nadh and fadh $ _2 $ ) from other steps of cellular respiration transfer their electrons to molecules near the beginning of the transport chain . in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy . some of the energy is used to pump h $ ^+ $ ions , moving them out of the matrix and into the intermembrane space . this pumping establishes an electrochemical gradient . splitting of oxygen to form water . at the end of the electron transport chain , electrons are transferred to molecular oxygen , which splits in half and takes up h $ ^+ $ to form water . gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane . as the electrons travel through the chain , they go from a higher to a lower energy level , moving from less electron-hungry to more electron-hungry molecules . energy is released in these “ downhill ” electron transfers , and several of the protein complexes use the released energy to pump protons from the mitochondrial matrix to the intermembrane space , forming a proton gradient . all of the electrons that enter the transport chain come from nadh and fadh $ _2 $ molecules produced during earlier stages of cellular respiration : glycolysis , pyruvate oxidation , and the citric acid cycle . nadh is very good at donating electrons in redox reactions ( that is , its electrons are at a high energy level ) , so it can transfer its electrons directly to complex i , turning back into nad $ ^+ $ . as electrons move through complex i in a series of redox reactions , energy is released , and the complex uses this energy to pump protons from the matrix into the intermembrane space . fadh $ _2 $ is not as good at donating electrons as nadh ( that is , its electrons are at a lower energy level ) , so it can not transfer its electrons to complex i . instead , it feeds them into the transport chain through complex ii , which does not pump protons across the membrane . because of this `` bypass , '' each fadh $ _2 $ molecule causes fewer protons to be pumped ( and contributes less to the proton gradient ) than an nadh . beyond the first two complexes , electrons from nadh and fadh $ _2 $ travel exactly the same route . both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water . four electrons are required to reduce each molecule of o $ _2 $ , and two water molecules are formed in the process . overall , what does the electron transport chain do for the cell ? it has two important functions : regenerates electron carriers . nadh and fadh $ _2 $ pass their electrons to the electron transport chain , turning back into nad $ ^+ $ and fad . this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix . this gradient represents a stored form of energy , and , as we ’ ll see , it can be used to make atp . chemiosmosis complexes i , iii , and iv of the electron transport chain are proton pumps . as electrons move energetically downhill , the complexes capture the released energy and use it to pump h $ ^+ $ ions from the matrix to the intermembrane space . this pumping forms an electrochemical gradient across the inner mitochondrial membrane . the gradient is sometimes called the proton-motive force , and you can think of it as a form of stored energy , kind of like a battery . like many other ions , protons ca n't pass directly through the phospholipid bilayer of the membrane because its core is too hydrophobic . instead , h $ ^+ $ ions can move down their concentration gradient only with the help of channel proteins that form hydrophilic tunnels across the membrane . in the inner mitochondrial membrane , h $ ^+ $ ions have just one channel available : a membrane-spanning protein known as atp synthase . conceptually , atp synthase is a lot like a turbine in a hydroelectric power plant . instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis . more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis . what would happen to the energy stored in the proton gradient if it were n't used to synthesize atp or do other cellular work ? it would be released as heat , and interestingly enough , some types of cells deliberately use the proton gradient for heat generation rather than atp synthesis . this might seem wasteful , but it 's an important strategy for animals that need to keep warm . for instance , hibernating mammals ( such as bears ) have specialized cells known as brown fat cells . in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers . however , most current sources estimate that the maximum atp yield for a molecule of glucose is around 30-32 atp $ ^ { 2,3,4 } $ . this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation . based on a lot of experimental work , it appears that four h $ ^+ $ ions must flow back into the matrix through atp synthase to power the synthesis of one atp molecule . when electrons from nadh move through the transport chain , about 10 h $ ^+ $ ions are pumped from the matrix to the intermembrane space , so each nadh yields about 2.5 atp . electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i . instead , it must hand its electrons off to a molecular “ shuttle system ” that delivers them , through a series of steps , to the electron transport chain . some cells of your body have a shuttle system that delivers electrons to the transport chain via fadh $ _2 $ . in this case , only 3 atp are produced for the two nadh of glycolysis . other cells of your body have a shuttle system that delivers the electrons via nadh , resulting in the production of 5 atp . in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced . cellular respiration is a nexus for many different metabolic pathways in the cell , forming a network that ’ s larger than the glucose breakdown pathways alone . self-check questions
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by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers .
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where did the net yield go down ?
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death . but have you ever wondered why that ’ s the case , or what exactly your body does with all that oxygen ? as it turns out , the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation , the final stage of cellular respiration . oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp . so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis . without enough atp , cells can ’ t carry out the reactions they need to function , and , after a long enough period of time , may even die . in this article , we 'll examine oxidative phosphorylation in depth , seeing how it provides most of the ready chemical energy ( atp ) used by the cells in your body . overview : oxidative phosphorylation the electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria . electrons are passed from one member of the transport chain to another in a series of redox reactions . energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ . reduced electron carriers ( nadh and fadh $ _2 $ ) from other steps of cellular respiration transfer their electrons to molecules near the beginning of the transport chain . in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy . some of the energy is used to pump h $ ^+ $ ions , moving them out of the matrix and into the intermembrane space . this pumping establishes an electrochemical gradient . splitting of oxygen to form water . at the end of the electron transport chain , electrons are transferred to molecular oxygen , which splits in half and takes up h $ ^+ $ to form water . gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane . as the electrons travel through the chain , they go from a higher to a lower energy level , moving from less electron-hungry to more electron-hungry molecules . energy is released in these “ downhill ” electron transfers , and several of the protein complexes use the released energy to pump protons from the mitochondrial matrix to the intermembrane space , forming a proton gradient . all of the electrons that enter the transport chain come from nadh and fadh $ _2 $ molecules produced during earlier stages of cellular respiration : glycolysis , pyruvate oxidation , and the citric acid cycle . nadh is very good at donating electrons in redox reactions ( that is , its electrons are at a high energy level ) , so it can transfer its electrons directly to complex i , turning back into nad $ ^+ $ . as electrons move through complex i in a series of redox reactions , energy is released , and the complex uses this energy to pump protons from the matrix into the intermembrane space . fadh $ _2 $ is not as good at donating electrons as nadh ( that is , its electrons are at a lower energy level ) , so it can not transfer its electrons to complex i . instead , it feeds them into the transport chain through complex ii , which does not pump protons across the membrane . because of this `` bypass , '' each fadh $ _2 $ molecule causes fewer protons to be pumped ( and contributes less to the proton gradient ) than an nadh . beyond the first two complexes , electrons from nadh and fadh $ _2 $ travel exactly the same route . both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water . four electrons are required to reduce each molecule of o $ _2 $ , and two water molecules are formed in the process . overall , what does the electron transport chain do for the cell ? it has two important functions : regenerates electron carriers . nadh and fadh $ _2 $ pass their electrons to the electron transport chain , turning back into nad $ ^+ $ and fad . this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix . this gradient represents a stored form of energy , and , as we ’ ll see , it can be used to make atp . chemiosmosis complexes i , iii , and iv of the electron transport chain are proton pumps . as electrons move energetically downhill , the complexes capture the released energy and use it to pump h $ ^+ $ ions from the matrix to the intermembrane space . this pumping forms an electrochemical gradient across the inner mitochondrial membrane . the gradient is sometimes called the proton-motive force , and you can think of it as a form of stored energy , kind of like a battery . like many other ions , protons ca n't pass directly through the phospholipid bilayer of the membrane because its core is too hydrophobic . instead , h $ ^+ $ ions can move down their concentration gradient only with the help of channel proteins that form hydrophilic tunnels across the membrane . in the inner mitochondrial membrane , h $ ^+ $ ions have just one channel available : a membrane-spanning protein known as atp synthase . conceptually , atp synthase is a lot like a turbine in a hydroelectric power plant . instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis . more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis . what would happen to the energy stored in the proton gradient if it were n't used to synthesize atp or do other cellular work ? it would be released as heat , and interestingly enough , some types of cells deliberately use the proton gradient for heat generation rather than atp synthesis . this might seem wasteful , but it 's an important strategy for animals that need to keep warm . for instance , hibernating mammals ( such as bears ) have specialized cells known as brown fat cells . in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers . however , most current sources estimate that the maximum atp yield for a molecule of glucose is around 30-32 atp $ ^ { 2,3,4 } $ . this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation . based on a lot of experimental work , it appears that four h $ ^+ $ ions must flow back into the matrix through atp synthase to power the synthesis of one atp molecule . when electrons from nadh move through the transport chain , about 10 h $ ^+ $ ions are pumped from the matrix to the intermembrane space , so each nadh yields about 2.5 atp . electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i . instead , it must hand its electrons off to a molecular “ shuttle system ” that delivers them , through a series of steps , to the electron transport chain . some cells of your body have a shuttle system that delivers electrons to the transport chain via fadh $ _2 $ . in this case , only 3 atp are produced for the two nadh of glycolysis . other cells of your body have a shuttle system that delivers the electrons via nadh , resulting in the production of 5 atp . in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced . cellular respiration is a nexus for many different metabolic pathways in the cell , forming a network that ’ s larger than the glucose breakdown pathways alone . self-check questions
|
energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ .
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what does substrate level phosphorylation means ?
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death . but have you ever wondered why that ’ s the case , or what exactly your body does with all that oxygen ? as it turns out , the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation , the final stage of cellular respiration . oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp . so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis . without enough atp , cells can ’ t carry out the reactions they need to function , and , after a long enough period of time , may even die . in this article , we 'll examine oxidative phosphorylation in depth , seeing how it provides most of the ready chemical energy ( atp ) used by the cells in your body . overview : oxidative phosphorylation the electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria . electrons are passed from one member of the transport chain to another in a series of redox reactions . energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ . reduced electron carriers ( nadh and fadh $ _2 $ ) from other steps of cellular respiration transfer their electrons to molecules near the beginning of the transport chain . in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy . some of the energy is used to pump h $ ^+ $ ions , moving them out of the matrix and into the intermembrane space . this pumping establishes an electrochemical gradient . splitting of oxygen to form water . at the end of the electron transport chain , electrons are transferred to molecular oxygen , which splits in half and takes up h $ ^+ $ to form water . gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane . as the electrons travel through the chain , they go from a higher to a lower energy level , moving from less electron-hungry to more electron-hungry molecules . energy is released in these “ downhill ” electron transfers , and several of the protein complexes use the released energy to pump protons from the mitochondrial matrix to the intermembrane space , forming a proton gradient . all of the electrons that enter the transport chain come from nadh and fadh $ _2 $ molecules produced during earlier stages of cellular respiration : glycolysis , pyruvate oxidation , and the citric acid cycle . nadh is very good at donating electrons in redox reactions ( that is , its electrons are at a high energy level ) , so it can transfer its electrons directly to complex i , turning back into nad $ ^+ $ . as electrons move through complex i in a series of redox reactions , energy is released , and the complex uses this energy to pump protons from the matrix into the intermembrane space . fadh $ _2 $ is not as good at donating electrons as nadh ( that is , its electrons are at a lower energy level ) , so it can not transfer its electrons to complex i . instead , it feeds them into the transport chain through complex ii , which does not pump protons across the membrane . because of this `` bypass , '' each fadh $ _2 $ molecule causes fewer protons to be pumped ( and contributes less to the proton gradient ) than an nadh . beyond the first two complexes , electrons from nadh and fadh $ _2 $ travel exactly the same route . both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water . four electrons are required to reduce each molecule of o $ _2 $ , and two water molecules are formed in the process . overall , what does the electron transport chain do for the cell ? it has two important functions : regenerates electron carriers . nadh and fadh $ _2 $ pass their electrons to the electron transport chain , turning back into nad $ ^+ $ and fad . this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix . this gradient represents a stored form of energy , and , as we ’ ll see , it can be used to make atp . chemiosmosis complexes i , iii , and iv of the electron transport chain are proton pumps . as electrons move energetically downhill , the complexes capture the released energy and use it to pump h $ ^+ $ ions from the matrix to the intermembrane space . this pumping forms an electrochemical gradient across the inner mitochondrial membrane . the gradient is sometimes called the proton-motive force , and you can think of it as a form of stored energy , kind of like a battery . like many other ions , protons ca n't pass directly through the phospholipid bilayer of the membrane because its core is too hydrophobic . instead , h $ ^+ $ ions can move down their concentration gradient only with the help of channel proteins that form hydrophilic tunnels across the membrane . in the inner mitochondrial membrane , h $ ^+ $ ions have just one channel available : a membrane-spanning protein known as atp synthase . conceptually , atp synthase is a lot like a turbine in a hydroelectric power plant . instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis . more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis . what would happen to the energy stored in the proton gradient if it were n't used to synthesize atp or do other cellular work ? it would be released as heat , and interestingly enough , some types of cells deliberately use the proton gradient for heat generation rather than atp synthesis . this might seem wasteful , but it 's an important strategy for animals that need to keep warm . for instance , hibernating mammals ( such as bears ) have specialized cells known as brown fat cells . in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers . however , most current sources estimate that the maximum atp yield for a molecule of glucose is around 30-32 atp $ ^ { 2,3,4 } $ . this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation . based on a lot of experimental work , it appears that four h $ ^+ $ ions must flow back into the matrix through atp synthase to power the synthesis of one atp molecule . when electrons from nadh move through the transport chain , about 10 h $ ^+ $ ions are pumped from the matrix to the intermembrane space , so each nadh yields about 2.5 atp . electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i . instead , it must hand its electrons off to a molecular “ shuttle system ” that delivers them , through a series of steps , to the electron transport chain . some cells of your body have a shuttle system that delivers electrons to the transport chain via fadh $ _2 $ . in this case , only 3 atp are produced for the two nadh of glycolysis . other cells of your body have a shuttle system that delivers the electrons via nadh , resulting in the production of 5 atp . in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced . cellular respiration is a nexus for many different metabolic pathways in the cell , forming a network that ’ s larger than the glucose breakdown pathways alone . self-check questions
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in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat .
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if the volume of the intermembrane space was increased , what effect would this have on the function of a mitochondrion ?
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death . but have you ever wondered why that ’ s the case , or what exactly your body does with all that oxygen ? as it turns out , the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation , the final stage of cellular respiration . oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp . so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis . without enough atp , cells can ’ t carry out the reactions they need to function , and , after a long enough period of time , may even die . in this article , we 'll examine oxidative phosphorylation in depth , seeing how it provides most of the ready chemical energy ( atp ) used by the cells in your body . overview : oxidative phosphorylation the electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria . electrons are passed from one member of the transport chain to another in a series of redox reactions . energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ . reduced electron carriers ( nadh and fadh $ _2 $ ) from other steps of cellular respiration transfer their electrons to molecules near the beginning of the transport chain . in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy . some of the energy is used to pump h $ ^+ $ ions , moving them out of the matrix and into the intermembrane space . this pumping establishes an electrochemical gradient . splitting of oxygen to form water . at the end of the electron transport chain , electrons are transferred to molecular oxygen , which splits in half and takes up h $ ^+ $ to form water . gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane . as the electrons travel through the chain , they go from a higher to a lower energy level , moving from less electron-hungry to more electron-hungry molecules . energy is released in these “ downhill ” electron transfers , and several of the protein complexes use the released energy to pump protons from the mitochondrial matrix to the intermembrane space , forming a proton gradient . all of the electrons that enter the transport chain come from nadh and fadh $ _2 $ molecules produced during earlier stages of cellular respiration : glycolysis , pyruvate oxidation , and the citric acid cycle . nadh is very good at donating electrons in redox reactions ( that is , its electrons are at a high energy level ) , so it can transfer its electrons directly to complex i , turning back into nad $ ^+ $ . as electrons move through complex i in a series of redox reactions , energy is released , and the complex uses this energy to pump protons from the matrix into the intermembrane space . fadh $ _2 $ is not as good at donating electrons as nadh ( that is , its electrons are at a lower energy level ) , so it can not transfer its electrons to complex i . instead , it feeds them into the transport chain through complex ii , which does not pump protons across the membrane . because of this `` bypass , '' each fadh $ _2 $ molecule causes fewer protons to be pumped ( and contributes less to the proton gradient ) than an nadh . beyond the first two complexes , electrons from nadh and fadh $ _2 $ travel exactly the same route . both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water . four electrons are required to reduce each molecule of o $ _2 $ , and two water molecules are formed in the process . overall , what does the electron transport chain do for the cell ? it has two important functions : regenerates electron carriers . nadh and fadh $ _2 $ pass their electrons to the electron transport chain , turning back into nad $ ^+ $ and fad . this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix . this gradient represents a stored form of energy , and , as we ’ ll see , it can be used to make atp . chemiosmosis complexes i , iii , and iv of the electron transport chain are proton pumps . as electrons move energetically downhill , the complexes capture the released energy and use it to pump h $ ^+ $ ions from the matrix to the intermembrane space . this pumping forms an electrochemical gradient across the inner mitochondrial membrane . the gradient is sometimes called the proton-motive force , and you can think of it as a form of stored energy , kind of like a battery . like many other ions , protons ca n't pass directly through the phospholipid bilayer of the membrane because its core is too hydrophobic . instead , h $ ^+ $ ions can move down their concentration gradient only with the help of channel proteins that form hydrophilic tunnels across the membrane . in the inner mitochondrial membrane , h $ ^+ $ ions have just one channel available : a membrane-spanning protein known as atp synthase . conceptually , atp synthase is a lot like a turbine in a hydroelectric power plant . instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis . more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis . what would happen to the energy stored in the proton gradient if it were n't used to synthesize atp or do other cellular work ? it would be released as heat , and interestingly enough , some types of cells deliberately use the proton gradient for heat generation rather than atp synthesis . this might seem wasteful , but it 's an important strategy for animals that need to keep warm . for instance , hibernating mammals ( such as bears ) have specialized cells known as brown fat cells . in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers . however , most current sources estimate that the maximum atp yield for a molecule of glucose is around 30-32 atp $ ^ { 2,3,4 } $ . this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation . based on a lot of experimental work , it appears that four h $ ^+ $ ions must flow back into the matrix through atp synthase to power the synthesis of one atp molecule . when electrons from nadh move through the transport chain , about 10 h $ ^+ $ ions are pumped from the matrix to the intermembrane space , so each nadh yields about 2.5 atp . electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i . instead , it must hand its electrons off to a molecular “ shuttle system ” that delivers them , through a series of steps , to the electron transport chain . some cells of your body have a shuttle system that delivers electrons to the transport chain via fadh $ _2 $ . in this case , only 3 atp are produced for the two nadh of glycolysis . other cells of your body have a shuttle system that delivers the electrons via nadh , resulting in the production of 5 atp . in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced . cellular respiration is a nexus for many different metabolic pathways in the cell , forming a network that ’ s larger than the glucose breakdown pathways alone . self-check questions
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as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane .
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how much h2o is produced is the electron transport chain ?
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death . but have you ever wondered why that ’ s the case , or what exactly your body does with all that oxygen ? as it turns out , the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation , the final stage of cellular respiration . oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp . so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis . without enough atp , cells can ’ t carry out the reactions they need to function , and , after a long enough period of time , may even die . in this article , we 'll examine oxidative phosphorylation in depth , seeing how it provides most of the ready chemical energy ( atp ) used by the cells in your body . overview : oxidative phosphorylation the electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria . electrons are passed from one member of the transport chain to another in a series of redox reactions . energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ . reduced electron carriers ( nadh and fadh $ _2 $ ) from other steps of cellular respiration transfer their electrons to molecules near the beginning of the transport chain . in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy . some of the energy is used to pump h $ ^+ $ ions , moving them out of the matrix and into the intermembrane space . this pumping establishes an electrochemical gradient . splitting of oxygen to form water . at the end of the electron transport chain , electrons are transferred to molecular oxygen , which splits in half and takes up h $ ^+ $ to form water . gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane . as the electrons travel through the chain , they go from a higher to a lower energy level , moving from less electron-hungry to more electron-hungry molecules . energy is released in these “ downhill ” electron transfers , and several of the protein complexes use the released energy to pump protons from the mitochondrial matrix to the intermembrane space , forming a proton gradient . all of the electrons that enter the transport chain come from nadh and fadh $ _2 $ molecules produced during earlier stages of cellular respiration : glycolysis , pyruvate oxidation , and the citric acid cycle . nadh is very good at donating electrons in redox reactions ( that is , its electrons are at a high energy level ) , so it can transfer its electrons directly to complex i , turning back into nad $ ^+ $ . as electrons move through complex i in a series of redox reactions , energy is released , and the complex uses this energy to pump protons from the matrix into the intermembrane space . fadh $ _2 $ is not as good at donating electrons as nadh ( that is , its electrons are at a lower energy level ) , so it can not transfer its electrons to complex i . instead , it feeds them into the transport chain through complex ii , which does not pump protons across the membrane . because of this `` bypass , '' each fadh $ _2 $ molecule causes fewer protons to be pumped ( and contributes less to the proton gradient ) than an nadh . beyond the first two complexes , electrons from nadh and fadh $ _2 $ travel exactly the same route . both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water . four electrons are required to reduce each molecule of o $ _2 $ , and two water molecules are formed in the process . overall , what does the electron transport chain do for the cell ? it has two important functions : regenerates electron carriers . nadh and fadh $ _2 $ pass their electrons to the electron transport chain , turning back into nad $ ^+ $ and fad . this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix . this gradient represents a stored form of energy , and , as we ’ ll see , it can be used to make atp . chemiosmosis complexes i , iii , and iv of the electron transport chain are proton pumps . as electrons move energetically downhill , the complexes capture the released energy and use it to pump h $ ^+ $ ions from the matrix to the intermembrane space . this pumping forms an electrochemical gradient across the inner mitochondrial membrane . the gradient is sometimes called the proton-motive force , and you can think of it as a form of stored energy , kind of like a battery . like many other ions , protons ca n't pass directly through the phospholipid bilayer of the membrane because its core is too hydrophobic . instead , h $ ^+ $ ions can move down their concentration gradient only with the help of channel proteins that form hydrophilic tunnels across the membrane . in the inner mitochondrial membrane , h $ ^+ $ ions have just one channel available : a membrane-spanning protein known as atp synthase . conceptually , atp synthase is a lot like a turbine in a hydroelectric power plant . instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis . more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis . what would happen to the energy stored in the proton gradient if it were n't used to synthesize atp or do other cellular work ? it would be released as heat , and interestingly enough , some types of cells deliberately use the proton gradient for heat generation rather than atp synthesis . this might seem wasteful , but it 's an important strategy for animals that need to keep warm . for instance , hibernating mammals ( such as bears ) have specialized cells known as brown fat cells . in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers . however , most current sources estimate that the maximum atp yield for a molecule of glucose is around 30-32 atp $ ^ { 2,3,4 } $ . this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation . based on a lot of experimental work , it appears that four h $ ^+ $ ions must flow back into the matrix through atp synthase to power the synthesis of one atp molecule . when electrons from nadh move through the transport chain , about 10 h $ ^+ $ ions are pumped from the matrix to the intermembrane space , so each nadh yields about 2.5 atp . electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i . instead , it must hand its electrons off to a molecular “ shuttle system ” that delivers them , through a series of steps , to the electron transport chain . some cells of your body have a shuttle system that delivers electrons to the transport chain via fadh $ _2 $ . in this case , only 3 atp are produced for the two nadh of glycolysis . other cells of your body have a shuttle system that delivers the electrons via nadh , resulting in the production of 5 atp . in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced . cellular respiration is a nexus for many different metabolic pathways in the cell , forming a network that ’ s larger than the glucose breakdown pathways alone . self-check questions
|
gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below .
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so is it possible that some electrons move from , lets say , enzyme 1 to enzyme 4 whithout getting to enzyme 3 ?
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death . but have you ever wondered why that ’ s the case , or what exactly your body does with all that oxygen ? as it turns out , the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation , the final stage of cellular respiration . oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp . so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis . without enough atp , cells can ’ t carry out the reactions they need to function , and , after a long enough period of time , may even die . in this article , we 'll examine oxidative phosphorylation in depth , seeing how it provides most of the ready chemical energy ( atp ) used by the cells in your body . overview : oxidative phosphorylation the electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria . electrons are passed from one member of the transport chain to another in a series of redox reactions . energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ . reduced electron carriers ( nadh and fadh $ _2 $ ) from other steps of cellular respiration transfer their electrons to molecules near the beginning of the transport chain . in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy . some of the energy is used to pump h $ ^+ $ ions , moving them out of the matrix and into the intermembrane space . this pumping establishes an electrochemical gradient . splitting of oxygen to form water . at the end of the electron transport chain , electrons are transferred to molecular oxygen , which splits in half and takes up h $ ^+ $ to form water . gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane . as the electrons travel through the chain , they go from a higher to a lower energy level , moving from less electron-hungry to more electron-hungry molecules . energy is released in these “ downhill ” electron transfers , and several of the protein complexes use the released energy to pump protons from the mitochondrial matrix to the intermembrane space , forming a proton gradient . all of the electrons that enter the transport chain come from nadh and fadh $ _2 $ molecules produced during earlier stages of cellular respiration : glycolysis , pyruvate oxidation , and the citric acid cycle . nadh is very good at donating electrons in redox reactions ( that is , its electrons are at a high energy level ) , so it can transfer its electrons directly to complex i , turning back into nad $ ^+ $ . as electrons move through complex i in a series of redox reactions , energy is released , and the complex uses this energy to pump protons from the matrix into the intermembrane space . fadh $ _2 $ is not as good at donating electrons as nadh ( that is , its electrons are at a lower energy level ) , so it can not transfer its electrons to complex i . instead , it feeds them into the transport chain through complex ii , which does not pump protons across the membrane . because of this `` bypass , '' each fadh $ _2 $ molecule causes fewer protons to be pumped ( and contributes less to the proton gradient ) than an nadh . beyond the first two complexes , electrons from nadh and fadh $ _2 $ travel exactly the same route . both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water . four electrons are required to reduce each molecule of o $ _2 $ , and two water molecules are formed in the process . overall , what does the electron transport chain do for the cell ? it has two important functions : regenerates electron carriers . nadh and fadh $ _2 $ pass their electrons to the electron transport chain , turning back into nad $ ^+ $ and fad . this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix . this gradient represents a stored form of energy , and , as we ’ ll see , it can be used to make atp . chemiosmosis complexes i , iii , and iv of the electron transport chain are proton pumps . as electrons move energetically downhill , the complexes capture the released energy and use it to pump h $ ^+ $ ions from the matrix to the intermembrane space . this pumping forms an electrochemical gradient across the inner mitochondrial membrane . the gradient is sometimes called the proton-motive force , and you can think of it as a form of stored energy , kind of like a battery . like many other ions , protons ca n't pass directly through the phospholipid bilayer of the membrane because its core is too hydrophobic . instead , h $ ^+ $ ions can move down their concentration gradient only with the help of channel proteins that form hydrophilic tunnels across the membrane . in the inner mitochondrial membrane , h $ ^+ $ ions have just one channel available : a membrane-spanning protein known as atp synthase . conceptually , atp synthase is a lot like a turbine in a hydroelectric power plant . instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis . more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis . what would happen to the energy stored in the proton gradient if it were n't used to synthesize atp or do other cellular work ? it would be released as heat , and interestingly enough , some types of cells deliberately use the proton gradient for heat generation rather than atp synthesis . this might seem wasteful , but it 's an important strategy for animals that need to keep warm . for instance , hibernating mammals ( such as bears ) have specialized cells known as brown fat cells . in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers . however , most current sources estimate that the maximum atp yield for a molecule of glucose is around 30-32 atp $ ^ { 2,3,4 } $ . this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation . based on a lot of experimental work , it appears that four h $ ^+ $ ions must flow back into the matrix through atp synthase to power the synthesis of one atp molecule . when electrons from nadh move through the transport chain , about 10 h $ ^+ $ ions are pumped from the matrix to the intermembrane space , so each nadh yields about 2.5 atp . electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i . instead , it must hand its electrons off to a molecular “ shuttle system ” that delivers them , through a series of steps , to the electron transport chain . some cells of your body have a shuttle system that delivers electrons to the transport chain via fadh $ _2 $ . in this case , only 3 atp are produced for the two nadh of glycolysis . other cells of your body have a shuttle system that delivers the electrons via nadh , resulting in the production of 5 atp . in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced . cellular respiration is a nexus for many different metabolic pathways in the cell , forming a network that ’ s larger than the glucose breakdown pathways alone . self-check questions
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more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis .
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why is cellular respiration considered exergonic ?
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death . but have you ever wondered why that ’ s the case , or what exactly your body does with all that oxygen ? as it turns out , the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation , the final stage of cellular respiration . oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp . so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis . without enough atp , cells can ’ t carry out the reactions they need to function , and , after a long enough period of time , may even die . in this article , we 'll examine oxidative phosphorylation in depth , seeing how it provides most of the ready chemical energy ( atp ) used by the cells in your body . overview : oxidative phosphorylation the electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria . electrons are passed from one member of the transport chain to another in a series of redox reactions . energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ . reduced electron carriers ( nadh and fadh $ _2 $ ) from other steps of cellular respiration transfer their electrons to molecules near the beginning of the transport chain . in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy . some of the energy is used to pump h $ ^+ $ ions , moving them out of the matrix and into the intermembrane space . this pumping establishes an electrochemical gradient . splitting of oxygen to form water . at the end of the electron transport chain , electrons are transferred to molecular oxygen , which splits in half and takes up h $ ^+ $ to form water . gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane . as the electrons travel through the chain , they go from a higher to a lower energy level , moving from less electron-hungry to more electron-hungry molecules . energy is released in these “ downhill ” electron transfers , and several of the protein complexes use the released energy to pump protons from the mitochondrial matrix to the intermembrane space , forming a proton gradient . all of the electrons that enter the transport chain come from nadh and fadh $ _2 $ molecules produced during earlier stages of cellular respiration : glycolysis , pyruvate oxidation , and the citric acid cycle . nadh is very good at donating electrons in redox reactions ( that is , its electrons are at a high energy level ) , so it can transfer its electrons directly to complex i , turning back into nad $ ^+ $ . as electrons move through complex i in a series of redox reactions , energy is released , and the complex uses this energy to pump protons from the matrix into the intermembrane space . fadh $ _2 $ is not as good at donating electrons as nadh ( that is , its electrons are at a lower energy level ) , so it can not transfer its electrons to complex i . instead , it feeds them into the transport chain through complex ii , which does not pump protons across the membrane . because of this `` bypass , '' each fadh $ _2 $ molecule causes fewer protons to be pumped ( and contributes less to the proton gradient ) than an nadh . beyond the first two complexes , electrons from nadh and fadh $ _2 $ travel exactly the same route . both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water . four electrons are required to reduce each molecule of o $ _2 $ , and two water molecules are formed in the process . overall , what does the electron transport chain do for the cell ? it has two important functions : regenerates electron carriers . nadh and fadh $ _2 $ pass their electrons to the electron transport chain , turning back into nad $ ^+ $ and fad . this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix . this gradient represents a stored form of energy , and , as we ’ ll see , it can be used to make atp . chemiosmosis complexes i , iii , and iv of the electron transport chain are proton pumps . as electrons move energetically downhill , the complexes capture the released energy and use it to pump h $ ^+ $ ions from the matrix to the intermembrane space . this pumping forms an electrochemical gradient across the inner mitochondrial membrane . the gradient is sometimes called the proton-motive force , and you can think of it as a form of stored energy , kind of like a battery . like many other ions , protons ca n't pass directly through the phospholipid bilayer of the membrane because its core is too hydrophobic . instead , h $ ^+ $ ions can move down their concentration gradient only with the help of channel proteins that form hydrophilic tunnels across the membrane . in the inner mitochondrial membrane , h $ ^+ $ ions have just one channel available : a membrane-spanning protein known as atp synthase . conceptually , atp synthase is a lot like a turbine in a hydroelectric power plant . instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis . more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis . what would happen to the energy stored in the proton gradient if it were n't used to synthesize atp or do other cellular work ? it would be released as heat , and interestingly enough , some types of cells deliberately use the proton gradient for heat generation rather than atp synthesis . this might seem wasteful , but it 's an important strategy for animals that need to keep warm . for instance , hibernating mammals ( such as bears ) have specialized cells known as brown fat cells . in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers . however , most current sources estimate that the maximum atp yield for a molecule of glucose is around 30-32 atp $ ^ { 2,3,4 } $ . this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation . based on a lot of experimental work , it appears that four h $ ^+ $ ions must flow back into the matrix through atp synthase to power the synthesis of one atp molecule . when electrons from nadh move through the transport chain , about 10 h $ ^+ $ ions are pumped from the matrix to the intermembrane space , so each nadh yields about 2.5 atp . electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i . instead , it must hand its electrons off to a molecular “ shuttle system ” that delivers them , through a series of steps , to the electron transport chain . some cells of your body have a shuttle system that delivers electrons to the transport chain via fadh $ _2 $ . in this case , only 3 atp are produced for the two nadh of glycolysis . other cells of your body have a shuttle system that delivers the electrons via nadh , resulting in the production of 5 atp . in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced . cellular respiration is a nexus for many different metabolic pathways in the cell , forming a network that ’ s larger than the glucose breakdown pathways alone . self-check questions
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by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers .
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i get that it releases energy in certain steps ( like oxidative phosphorylation ) but overall , is n't the main point of cellular respiration to generate atp ?
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death . but have you ever wondered why that ’ s the case , or what exactly your body does with all that oxygen ? as it turns out , the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation , the final stage of cellular respiration . oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp . so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis . without enough atp , cells can ’ t carry out the reactions they need to function , and , after a long enough period of time , may even die . in this article , we 'll examine oxidative phosphorylation in depth , seeing how it provides most of the ready chemical energy ( atp ) used by the cells in your body . overview : oxidative phosphorylation the electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria . electrons are passed from one member of the transport chain to another in a series of redox reactions . energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ . reduced electron carriers ( nadh and fadh $ _2 $ ) from other steps of cellular respiration transfer their electrons to molecules near the beginning of the transport chain . in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy . some of the energy is used to pump h $ ^+ $ ions , moving them out of the matrix and into the intermembrane space . this pumping establishes an electrochemical gradient . splitting of oxygen to form water . at the end of the electron transport chain , electrons are transferred to molecular oxygen , which splits in half and takes up h $ ^+ $ to form water . gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane . as the electrons travel through the chain , they go from a higher to a lower energy level , moving from less electron-hungry to more electron-hungry molecules . energy is released in these “ downhill ” electron transfers , and several of the protein complexes use the released energy to pump protons from the mitochondrial matrix to the intermembrane space , forming a proton gradient . all of the electrons that enter the transport chain come from nadh and fadh $ _2 $ molecules produced during earlier stages of cellular respiration : glycolysis , pyruvate oxidation , and the citric acid cycle . nadh is very good at donating electrons in redox reactions ( that is , its electrons are at a high energy level ) , so it can transfer its electrons directly to complex i , turning back into nad $ ^+ $ . as electrons move through complex i in a series of redox reactions , energy is released , and the complex uses this energy to pump protons from the matrix into the intermembrane space . fadh $ _2 $ is not as good at donating electrons as nadh ( that is , its electrons are at a lower energy level ) , so it can not transfer its electrons to complex i . instead , it feeds them into the transport chain through complex ii , which does not pump protons across the membrane . because of this `` bypass , '' each fadh $ _2 $ molecule causes fewer protons to be pumped ( and contributes less to the proton gradient ) than an nadh . beyond the first two complexes , electrons from nadh and fadh $ _2 $ travel exactly the same route . both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water . four electrons are required to reduce each molecule of o $ _2 $ , and two water molecules are formed in the process . overall , what does the electron transport chain do for the cell ? it has two important functions : regenerates electron carriers . nadh and fadh $ _2 $ pass their electrons to the electron transport chain , turning back into nad $ ^+ $ and fad . this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix . this gradient represents a stored form of energy , and , as we ’ ll see , it can be used to make atp . chemiosmosis complexes i , iii , and iv of the electron transport chain are proton pumps . as electrons move energetically downhill , the complexes capture the released energy and use it to pump h $ ^+ $ ions from the matrix to the intermembrane space . this pumping forms an electrochemical gradient across the inner mitochondrial membrane . the gradient is sometimes called the proton-motive force , and you can think of it as a form of stored energy , kind of like a battery . like many other ions , protons ca n't pass directly through the phospholipid bilayer of the membrane because its core is too hydrophobic . instead , h $ ^+ $ ions can move down their concentration gradient only with the help of channel proteins that form hydrophilic tunnels across the membrane . in the inner mitochondrial membrane , h $ ^+ $ ions have just one channel available : a membrane-spanning protein known as atp synthase . conceptually , atp synthase is a lot like a turbine in a hydroelectric power plant . instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis . more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis . what would happen to the energy stored in the proton gradient if it were n't used to synthesize atp or do other cellular work ? it would be released as heat , and interestingly enough , some types of cells deliberately use the proton gradient for heat generation rather than atp synthesis . this might seem wasteful , but it 's an important strategy for animals that need to keep warm . for instance , hibernating mammals ( such as bears ) have specialized cells known as brown fat cells . in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers . however , most current sources estimate that the maximum atp yield for a molecule of glucose is around 30-32 atp $ ^ { 2,3,4 } $ . this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation . based on a lot of experimental work , it appears that four h $ ^+ $ ions must flow back into the matrix through atp synthase to power the synthesis of one atp molecule . when electrons from nadh move through the transport chain , about 10 h $ ^+ $ ions are pumped from the matrix to the intermembrane space , so each nadh yields about 2.5 atp . electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i . instead , it must hand its electrons off to a molecular “ shuttle system ” that delivers them , through a series of steps , to the electron transport chain . some cells of your body have a shuttle system that delivers electrons to the transport chain via fadh $ _2 $ . in this case , only 3 atp are produced for the two nadh of glycolysis . other cells of your body have a shuttle system that delivers the electrons via nadh , resulting in the production of 5 atp . in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced . cellular respiration is a nexus for many different metabolic pathways in the cell , forming a network that ’ s larger than the glucose breakdown pathways alone . self-check questions
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both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water .
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if the h+ ions are pumped across the membrane , how do the electrons at the end of the etc and the split molecular oxygen atoms get access to h+ ions in the matrix ?
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death . but have you ever wondered why that ’ s the case , or what exactly your body does with all that oxygen ? as it turns out , the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation , the final stage of cellular respiration . oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp . so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis . without enough atp , cells can ’ t carry out the reactions they need to function , and , after a long enough period of time , may even die . in this article , we 'll examine oxidative phosphorylation in depth , seeing how it provides most of the ready chemical energy ( atp ) used by the cells in your body . overview : oxidative phosphorylation the electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria . electrons are passed from one member of the transport chain to another in a series of redox reactions . energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ . reduced electron carriers ( nadh and fadh $ _2 $ ) from other steps of cellular respiration transfer their electrons to molecules near the beginning of the transport chain . in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy . some of the energy is used to pump h $ ^+ $ ions , moving them out of the matrix and into the intermembrane space . this pumping establishes an electrochemical gradient . splitting of oxygen to form water . at the end of the electron transport chain , electrons are transferred to molecular oxygen , which splits in half and takes up h $ ^+ $ to form water . gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane . as the electrons travel through the chain , they go from a higher to a lower energy level , moving from less electron-hungry to more electron-hungry molecules . energy is released in these “ downhill ” electron transfers , and several of the protein complexes use the released energy to pump protons from the mitochondrial matrix to the intermembrane space , forming a proton gradient . all of the electrons that enter the transport chain come from nadh and fadh $ _2 $ molecules produced during earlier stages of cellular respiration : glycolysis , pyruvate oxidation , and the citric acid cycle . nadh is very good at donating electrons in redox reactions ( that is , its electrons are at a high energy level ) , so it can transfer its electrons directly to complex i , turning back into nad $ ^+ $ . as electrons move through complex i in a series of redox reactions , energy is released , and the complex uses this energy to pump protons from the matrix into the intermembrane space . fadh $ _2 $ is not as good at donating electrons as nadh ( that is , its electrons are at a lower energy level ) , so it can not transfer its electrons to complex i . instead , it feeds them into the transport chain through complex ii , which does not pump protons across the membrane . because of this `` bypass , '' each fadh $ _2 $ molecule causes fewer protons to be pumped ( and contributes less to the proton gradient ) than an nadh . beyond the first two complexes , electrons from nadh and fadh $ _2 $ travel exactly the same route . both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water . four electrons are required to reduce each molecule of o $ _2 $ , and two water molecules are formed in the process . overall , what does the electron transport chain do for the cell ? it has two important functions : regenerates electron carriers . nadh and fadh $ _2 $ pass their electrons to the electron transport chain , turning back into nad $ ^+ $ and fad . this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix . this gradient represents a stored form of energy , and , as we ’ ll see , it can be used to make atp . chemiosmosis complexes i , iii , and iv of the electron transport chain are proton pumps . as electrons move energetically downhill , the complexes capture the released energy and use it to pump h $ ^+ $ ions from the matrix to the intermembrane space . this pumping forms an electrochemical gradient across the inner mitochondrial membrane . the gradient is sometimes called the proton-motive force , and you can think of it as a form of stored energy , kind of like a battery . like many other ions , protons ca n't pass directly through the phospholipid bilayer of the membrane because its core is too hydrophobic . instead , h $ ^+ $ ions can move down their concentration gradient only with the help of channel proteins that form hydrophilic tunnels across the membrane . in the inner mitochondrial membrane , h $ ^+ $ ions have just one channel available : a membrane-spanning protein known as atp synthase . conceptually , atp synthase is a lot like a turbine in a hydroelectric power plant . instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis . more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis . what would happen to the energy stored in the proton gradient if it were n't used to synthesize atp or do other cellular work ? it would be released as heat , and interestingly enough , some types of cells deliberately use the proton gradient for heat generation rather than atp synthesis . this might seem wasteful , but it 's an important strategy for animals that need to keep warm . for instance , hibernating mammals ( such as bears ) have specialized cells known as brown fat cells . in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers . however , most current sources estimate that the maximum atp yield for a molecule of glucose is around 30-32 atp $ ^ { 2,3,4 } $ . this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation . based on a lot of experimental work , it appears that four h $ ^+ $ ions must flow back into the matrix through atp synthase to power the synthesis of one atp molecule . when electrons from nadh move through the transport chain , about 10 h $ ^+ $ ions are pumped from the matrix to the intermembrane space , so each nadh yields about 2.5 atp . electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i . instead , it must hand its electrons off to a molecular “ shuttle system ” that delivers them , through a series of steps , to the electron transport chain . some cells of your body have a shuttle system that delivers electrons to the transport chain via fadh $ _2 $ . in this case , only 3 atp are produced for the two nadh of glycolysis . other cells of your body have a shuttle system that delivers the electrons via nadh , resulting in the production of 5 atp . in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced . cellular respiration is a nexus for many different metabolic pathways in the cell , forming a network that ’ s larger than the glucose breakdown pathways alone . self-check questions
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by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers .
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the whole reaction of cellular respiration is : c6h12o6 + 6o2 - > 6co2 + 6h2o in glycolysis there are 2 h2o produced per one glucose in krebs cycle there are 4 h2o used per one glucose so , before etc there are net 2 h2o used per one glucose does n't it means there should be 8 h2o produced in etc ?
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death . but have you ever wondered why that ’ s the case , or what exactly your body does with all that oxygen ? as it turns out , the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation , the final stage of cellular respiration . oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp . so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis . without enough atp , cells can ’ t carry out the reactions they need to function , and , after a long enough period of time , may even die . in this article , we 'll examine oxidative phosphorylation in depth , seeing how it provides most of the ready chemical energy ( atp ) used by the cells in your body . overview : oxidative phosphorylation the electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria . electrons are passed from one member of the transport chain to another in a series of redox reactions . energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ . reduced electron carriers ( nadh and fadh $ _2 $ ) from other steps of cellular respiration transfer their electrons to molecules near the beginning of the transport chain . in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy . some of the energy is used to pump h $ ^+ $ ions , moving them out of the matrix and into the intermembrane space . this pumping establishes an electrochemical gradient . splitting of oxygen to form water . at the end of the electron transport chain , electrons are transferred to molecular oxygen , which splits in half and takes up h $ ^+ $ to form water . gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane . as the electrons travel through the chain , they go from a higher to a lower energy level , moving from less electron-hungry to more electron-hungry molecules . energy is released in these “ downhill ” electron transfers , and several of the protein complexes use the released energy to pump protons from the mitochondrial matrix to the intermembrane space , forming a proton gradient . all of the electrons that enter the transport chain come from nadh and fadh $ _2 $ molecules produced during earlier stages of cellular respiration : glycolysis , pyruvate oxidation , and the citric acid cycle . nadh is very good at donating electrons in redox reactions ( that is , its electrons are at a high energy level ) , so it can transfer its electrons directly to complex i , turning back into nad $ ^+ $ . as electrons move through complex i in a series of redox reactions , energy is released , and the complex uses this energy to pump protons from the matrix into the intermembrane space . fadh $ _2 $ is not as good at donating electrons as nadh ( that is , its electrons are at a lower energy level ) , so it can not transfer its electrons to complex i . instead , it feeds them into the transport chain through complex ii , which does not pump protons across the membrane . because of this `` bypass , '' each fadh $ _2 $ molecule causes fewer protons to be pumped ( and contributes less to the proton gradient ) than an nadh . beyond the first two complexes , electrons from nadh and fadh $ _2 $ travel exactly the same route . both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water . four electrons are required to reduce each molecule of o $ _2 $ , and two water molecules are formed in the process . overall , what does the electron transport chain do for the cell ? it has two important functions : regenerates electron carriers . nadh and fadh $ _2 $ pass their electrons to the electron transport chain , turning back into nad $ ^+ $ and fad . this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix . this gradient represents a stored form of energy , and , as we ’ ll see , it can be used to make atp . chemiosmosis complexes i , iii , and iv of the electron transport chain are proton pumps . as electrons move energetically downhill , the complexes capture the released energy and use it to pump h $ ^+ $ ions from the matrix to the intermembrane space . this pumping forms an electrochemical gradient across the inner mitochondrial membrane . the gradient is sometimes called the proton-motive force , and you can think of it as a form of stored energy , kind of like a battery . like many other ions , protons ca n't pass directly through the phospholipid bilayer of the membrane because its core is too hydrophobic . instead , h $ ^+ $ ions can move down their concentration gradient only with the help of channel proteins that form hydrophilic tunnels across the membrane . in the inner mitochondrial membrane , h $ ^+ $ ions have just one channel available : a membrane-spanning protein known as atp synthase . conceptually , atp synthase is a lot like a turbine in a hydroelectric power plant . instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis . more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis . what would happen to the energy stored in the proton gradient if it were n't used to synthesize atp or do other cellular work ? it would be released as heat , and interestingly enough , some types of cells deliberately use the proton gradient for heat generation rather than atp synthesis . this might seem wasteful , but it 's an important strategy for animals that need to keep warm . for instance , hibernating mammals ( such as bears ) have specialized cells known as brown fat cells . in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers . however , most current sources estimate that the maximum atp yield for a molecule of glucose is around 30-32 atp $ ^ { 2,3,4 } $ . this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation . based on a lot of experimental work , it appears that four h $ ^+ $ ions must flow back into the matrix through atp synthase to power the synthesis of one atp molecule . when electrons from nadh move through the transport chain , about 10 h $ ^+ $ ions are pumped from the matrix to the intermembrane space , so each nadh yields about 2.5 atp . electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i . instead , it must hand its electrons off to a molecular “ shuttle system ” that delivers them , through a series of steps , to the electron transport chain . some cells of your body have a shuttle system that delivers electrons to the transport chain via fadh $ _2 $ . in this case , only 3 atp are produced for the two nadh of glycolysis . other cells of your body have a shuttle system that delivers the electrons via nadh , resulting in the production of 5 atp . in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced . cellular respiration is a nexus for many different metabolic pathways in the cell , forming a network that ’ s larger than the glucose breakdown pathways alone . self-check questions
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as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane .
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how much does cyanide reduces the yield of atp in electron transport chain ?
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death . but have you ever wondered why that ’ s the case , or what exactly your body does with all that oxygen ? as it turns out , the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation , the final stage of cellular respiration . oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp . so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis . without enough atp , cells can ’ t carry out the reactions they need to function , and , after a long enough period of time , may even die . in this article , we 'll examine oxidative phosphorylation in depth , seeing how it provides most of the ready chemical energy ( atp ) used by the cells in your body . overview : oxidative phosphorylation the electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria . electrons are passed from one member of the transport chain to another in a series of redox reactions . energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ . reduced electron carriers ( nadh and fadh $ _2 $ ) from other steps of cellular respiration transfer their electrons to molecules near the beginning of the transport chain . in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy . some of the energy is used to pump h $ ^+ $ ions , moving them out of the matrix and into the intermembrane space . this pumping establishes an electrochemical gradient . splitting of oxygen to form water . at the end of the electron transport chain , electrons are transferred to molecular oxygen , which splits in half and takes up h $ ^+ $ to form water . gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane . as the electrons travel through the chain , they go from a higher to a lower energy level , moving from less electron-hungry to more electron-hungry molecules . energy is released in these “ downhill ” electron transfers , and several of the protein complexes use the released energy to pump protons from the mitochondrial matrix to the intermembrane space , forming a proton gradient . all of the electrons that enter the transport chain come from nadh and fadh $ _2 $ molecules produced during earlier stages of cellular respiration : glycolysis , pyruvate oxidation , and the citric acid cycle . nadh is very good at donating electrons in redox reactions ( that is , its electrons are at a high energy level ) , so it can transfer its electrons directly to complex i , turning back into nad $ ^+ $ . as electrons move through complex i in a series of redox reactions , energy is released , and the complex uses this energy to pump protons from the matrix into the intermembrane space . fadh $ _2 $ is not as good at donating electrons as nadh ( that is , its electrons are at a lower energy level ) , so it can not transfer its electrons to complex i . instead , it feeds them into the transport chain through complex ii , which does not pump protons across the membrane . because of this `` bypass , '' each fadh $ _2 $ molecule causes fewer protons to be pumped ( and contributes less to the proton gradient ) than an nadh . beyond the first two complexes , electrons from nadh and fadh $ _2 $ travel exactly the same route . both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water . four electrons are required to reduce each molecule of o $ _2 $ , and two water molecules are formed in the process . overall , what does the electron transport chain do for the cell ? it has two important functions : regenerates electron carriers . nadh and fadh $ _2 $ pass their electrons to the electron transport chain , turning back into nad $ ^+ $ and fad . this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix . this gradient represents a stored form of energy , and , as we ’ ll see , it can be used to make atp . chemiosmosis complexes i , iii , and iv of the electron transport chain are proton pumps . as electrons move energetically downhill , the complexes capture the released energy and use it to pump h $ ^+ $ ions from the matrix to the intermembrane space . this pumping forms an electrochemical gradient across the inner mitochondrial membrane . the gradient is sometimes called the proton-motive force , and you can think of it as a form of stored energy , kind of like a battery . like many other ions , protons ca n't pass directly through the phospholipid bilayer of the membrane because its core is too hydrophobic . instead , h $ ^+ $ ions can move down their concentration gradient only with the help of channel proteins that form hydrophilic tunnels across the membrane . in the inner mitochondrial membrane , h $ ^+ $ ions have just one channel available : a membrane-spanning protein known as atp synthase . conceptually , atp synthase is a lot like a turbine in a hydroelectric power plant . instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis . more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis . what would happen to the energy stored in the proton gradient if it were n't used to synthesize atp or do other cellular work ? it would be released as heat , and interestingly enough , some types of cells deliberately use the proton gradient for heat generation rather than atp synthesis . this might seem wasteful , but it 's an important strategy for animals that need to keep warm . for instance , hibernating mammals ( such as bears ) have specialized cells known as brown fat cells . in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers . however , most current sources estimate that the maximum atp yield for a molecule of glucose is around 30-32 atp $ ^ { 2,3,4 } $ . this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation . based on a lot of experimental work , it appears that four h $ ^+ $ ions must flow back into the matrix through atp synthase to power the synthesis of one atp molecule . when electrons from nadh move through the transport chain , about 10 h $ ^+ $ ions are pumped from the matrix to the intermembrane space , so each nadh yields about 2.5 atp . electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i . instead , it must hand its electrons off to a molecular “ shuttle system ” that delivers them , through a series of steps , to the electron transport chain . some cells of your body have a shuttle system that delivers electrons to the transport chain via fadh $ _2 $ . in this case , only 3 atp are produced for the two nadh of glycolysis . other cells of your body have a shuttle system that delivers the electrons via nadh , resulting in the production of 5 atp . in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced . cellular respiration is a nexus for many different metabolic pathways in the cell , forming a network that ’ s larger than the glucose breakdown pathways alone . self-check questions
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electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i .
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so if i 'm right , for every pyruvate 2 h2o molecules are produced ?
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death . but have you ever wondered why that ’ s the case , or what exactly your body does with all that oxygen ? as it turns out , the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation , the final stage of cellular respiration . oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp . so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis . without enough atp , cells can ’ t carry out the reactions they need to function , and , after a long enough period of time , may even die . in this article , we 'll examine oxidative phosphorylation in depth , seeing how it provides most of the ready chemical energy ( atp ) used by the cells in your body . overview : oxidative phosphorylation the electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria . electrons are passed from one member of the transport chain to another in a series of redox reactions . energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ . reduced electron carriers ( nadh and fadh $ _2 $ ) from other steps of cellular respiration transfer their electrons to molecules near the beginning of the transport chain . in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy . some of the energy is used to pump h $ ^+ $ ions , moving them out of the matrix and into the intermembrane space . this pumping establishes an electrochemical gradient . splitting of oxygen to form water . at the end of the electron transport chain , electrons are transferred to molecular oxygen , which splits in half and takes up h $ ^+ $ to form water . gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane . as the electrons travel through the chain , they go from a higher to a lower energy level , moving from less electron-hungry to more electron-hungry molecules . energy is released in these “ downhill ” electron transfers , and several of the protein complexes use the released energy to pump protons from the mitochondrial matrix to the intermembrane space , forming a proton gradient . all of the electrons that enter the transport chain come from nadh and fadh $ _2 $ molecules produced during earlier stages of cellular respiration : glycolysis , pyruvate oxidation , and the citric acid cycle . nadh is very good at donating electrons in redox reactions ( that is , its electrons are at a high energy level ) , so it can transfer its electrons directly to complex i , turning back into nad $ ^+ $ . as electrons move through complex i in a series of redox reactions , energy is released , and the complex uses this energy to pump protons from the matrix into the intermembrane space . fadh $ _2 $ is not as good at donating electrons as nadh ( that is , its electrons are at a lower energy level ) , so it can not transfer its electrons to complex i . instead , it feeds them into the transport chain through complex ii , which does not pump protons across the membrane . because of this `` bypass , '' each fadh $ _2 $ molecule causes fewer protons to be pumped ( and contributes less to the proton gradient ) than an nadh . beyond the first two complexes , electrons from nadh and fadh $ _2 $ travel exactly the same route . both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water . four electrons are required to reduce each molecule of o $ _2 $ , and two water molecules are formed in the process . overall , what does the electron transport chain do for the cell ? it has two important functions : regenerates electron carriers . nadh and fadh $ _2 $ pass their electrons to the electron transport chain , turning back into nad $ ^+ $ and fad . this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix . this gradient represents a stored form of energy , and , as we ’ ll see , it can be used to make atp . chemiosmosis complexes i , iii , and iv of the electron transport chain are proton pumps . as electrons move energetically downhill , the complexes capture the released energy and use it to pump h $ ^+ $ ions from the matrix to the intermembrane space . this pumping forms an electrochemical gradient across the inner mitochondrial membrane . the gradient is sometimes called the proton-motive force , and you can think of it as a form of stored energy , kind of like a battery . like many other ions , protons ca n't pass directly through the phospholipid bilayer of the membrane because its core is too hydrophobic . instead , h $ ^+ $ ions can move down their concentration gradient only with the help of channel proteins that form hydrophilic tunnels across the membrane . in the inner mitochondrial membrane , h $ ^+ $ ions have just one channel available : a membrane-spanning protein known as atp synthase . conceptually , atp synthase is a lot like a turbine in a hydroelectric power plant . instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis . more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis . what would happen to the energy stored in the proton gradient if it were n't used to synthesize atp or do other cellular work ? it would be released as heat , and interestingly enough , some types of cells deliberately use the proton gradient for heat generation rather than atp synthesis . this might seem wasteful , but it 's an important strategy for animals that need to keep warm . for instance , hibernating mammals ( such as bears ) have specialized cells known as brown fat cells . in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers . however , most current sources estimate that the maximum atp yield for a molecule of glucose is around 30-32 atp $ ^ { 2,3,4 } $ . this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation . based on a lot of experimental work , it appears that four h $ ^+ $ ions must flow back into the matrix through atp synthase to power the synthesis of one atp molecule . when electrons from nadh move through the transport chain , about 10 h $ ^+ $ ions are pumped from the matrix to the intermembrane space , so each nadh yields about 2.5 atp . electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i . instead , it must hand its electrons off to a molecular “ shuttle system ” that delivers them , through a series of steps , to the electron transport chain . some cells of your body have a shuttle system that delivers electrons to the transport chain via fadh $ _2 $ . in this case , only 3 atp are produced for the two nadh of glycolysis . other cells of your body have a shuttle system that delivers the electrons via nadh , resulting in the production of 5 atp . in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced . cellular respiration is a nexus for many different metabolic pathways in the cell , forming a network that ’ s larger than the glucose breakdown pathways alone . self-check questions
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death .
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but the overall reaction for the aerobic metabolism says 6 o2 's are needed ... can someone explain to me where we need the extra 4 o2 's for ?
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death . but have you ever wondered why that ’ s the case , or what exactly your body does with all that oxygen ? as it turns out , the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation , the final stage of cellular respiration . oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp . so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis . without enough atp , cells can ’ t carry out the reactions they need to function , and , after a long enough period of time , may even die . in this article , we 'll examine oxidative phosphorylation in depth , seeing how it provides most of the ready chemical energy ( atp ) used by the cells in your body . overview : oxidative phosphorylation the electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria . electrons are passed from one member of the transport chain to another in a series of redox reactions . energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ . reduced electron carriers ( nadh and fadh $ _2 $ ) from other steps of cellular respiration transfer their electrons to molecules near the beginning of the transport chain . in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy . some of the energy is used to pump h $ ^+ $ ions , moving them out of the matrix and into the intermembrane space . this pumping establishes an electrochemical gradient . splitting of oxygen to form water . at the end of the electron transport chain , electrons are transferred to molecular oxygen , which splits in half and takes up h $ ^+ $ to form water . gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane . as the electrons travel through the chain , they go from a higher to a lower energy level , moving from less electron-hungry to more electron-hungry molecules . energy is released in these “ downhill ” electron transfers , and several of the protein complexes use the released energy to pump protons from the mitochondrial matrix to the intermembrane space , forming a proton gradient . all of the electrons that enter the transport chain come from nadh and fadh $ _2 $ molecules produced during earlier stages of cellular respiration : glycolysis , pyruvate oxidation , and the citric acid cycle . nadh is very good at donating electrons in redox reactions ( that is , its electrons are at a high energy level ) , so it can transfer its electrons directly to complex i , turning back into nad $ ^+ $ . as electrons move through complex i in a series of redox reactions , energy is released , and the complex uses this energy to pump protons from the matrix into the intermembrane space . fadh $ _2 $ is not as good at donating electrons as nadh ( that is , its electrons are at a lower energy level ) , so it can not transfer its electrons to complex i . instead , it feeds them into the transport chain through complex ii , which does not pump protons across the membrane . because of this `` bypass , '' each fadh $ _2 $ molecule causes fewer protons to be pumped ( and contributes less to the proton gradient ) than an nadh . beyond the first two complexes , electrons from nadh and fadh $ _2 $ travel exactly the same route . both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water . four electrons are required to reduce each molecule of o $ _2 $ , and two water molecules are formed in the process . overall , what does the electron transport chain do for the cell ? it has two important functions : regenerates electron carriers . nadh and fadh $ _2 $ pass their electrons to the electron transport chain , turning back into nad $ ^+ $ and fad . this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix . this gradient represents a stored form of energy , and , as we ’ ll see , it can be used to make atp . chemiosmosis complexes i , iii , and iv of the electron transport chain are proton pumps . as electrons move energetically downhill , the complexes capture the released energy and use it to pump h $ ^+ $ ions from the matrix to the intermembrane space . this pumping forms an electrochemical gradient across the inner mitochondrial membrane . the gradient is sometimes called the proton-motive force , and you can think of it as a form of stored energy , kind of like a battery . like many other ions , protons ca n't pass directly through the phospholipid bilayer of the membrane because its core is too hydrophobic . instead , h $ ^+ $ ions can move down their concentration gradient only with the help of channel proteins that form hydrophilic tunnels across the membrane . in the inner mitochondrial membrane , h $ ^+ $ ions have just one channel available : a membrane-spanning protein known as atp synthase . conceptually , atp synthase is a lot like a turbine in a hydroelectric power plant . instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis . more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis . what would happen to the energy stored in the proton gradient if it were n't used to synthesize atp or do other cellular work ? it would be released as heat , and interestingly enough , some types of cells deliberately use the proton gradient for heat generation rather than atp synthesis . this might seem wasteful , but it 's an important strategy for animals that need to keep warm . for instance , hibernating mammals ( such as bears ) have specialized cells known as brown fat cells . in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers . however , most current sources estimate that the maximum atp yield for a molecule of glucose is around 30-32 atp $ ^ { 2,3,4 } $ . this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation . based on a lot of experimental work , it appears that four h $ ^+ $ ions must flow back into the matrix through atp synthase to power the synthesis of one atp molecule . when electrons from nadh move through the transport chain , about 10 h $ ^+ $ ions are pumped from the matrix to the intermembrane space , so each nadh yields about 2.5 atp . electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i . instead , it must hand its electrons off to a molecular “ shuttle system ” that delivers them , through a series of steps , to the electron transport chain . some cells of your body have a shuttle system that delivers electrons to the transport chain via fadh $ _2 $ . in this case , only 3 atp are produced for the two nadh of glycolysis . other cells of your body have a shuttle system that delivers the electrons via nadh , resulting in the production of 5 atp . in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced . cellular respiration is a nexus for many different metabolic pathways in the cell , forming a network that ’ s larger than the glucose breakdown pathways alone . self-check questions
|
this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation .
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why are there two different methods to form atp in humans ?
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death . but have you ever wondered why that ’ s the case , or what exactly your body does with all that oxygen ? as it turns out , the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation , the final stage of cellular respiration . oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp . so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis . without enough atp , cells can ’ t carry out the reactions they need to function , and , after a long enough period of time , may even die . in this article , we 'll examine oxidative phosphorylation in depth , seeing how it provides most of the ready chemical energy ( atp ) used by the cells in your body . overview : oxidative phosphorylation the electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria . electrons are passed from one member of the transport chain to another in a series of redox reactions . energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ . reduced electron carriers ( nadh and fadh $ _2 $ ) from other steps of cellular respiration transfer their electrons to molecules near the beginning of the transport chain . in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy . some of the energy is used to pump h $ ^+ $ ions , moving them out of the matrix and into the intermembrane space . this pumping establishes an electrochemical gradient . splitting of oxygen to form water . at the end of the electron transport chain , electrons are transferred to molecular oxygen , which splits in half and takes up h $ ^+ $ to form water . gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane . as the electrons travel through the chain , they go from a higher to a lower energy level , moving from less electron-hungry to more electron-hungry molecules . energy is released in these “ downhill ” electron transfers , and several of the protein complexes use the released energy to pump protons from the mitochondrial matrix to the intermembrane space , forming a proton gradient . all of the electrons that enter the transport chain come from nadh and fadh $ _2 $ molecules produced during earlier stages of cellular respiration : glycolysis , pyruvate oxidation , and the citric acid cycle . nadh is very good at donating electrons in redox reactions ( that is , its electrons are at a high energy level ) , so it can transfer its electrons directly to complex i , turning back into nad $ ^+ $ . as electrons move through complex i in a series of redox reactions , energy is released , and the complex uses this energy to pump protons from the matrix into the intermembrane space . fadh $ _2 $ is not as good at donating electrons as nadh ( that is , its electrons are at a lower energy level ) , so it can not transfer its electrons to complex i . instead , it feeds them into the transport chain through complex ii , which does not pump protons across the membrane . because of this `` bypass , '' each fadh $ _2 $ molecule causes fewer protons to be pumped ( and contributes less to the proton gradient ) than an nadh . beyond the first two complexes , electrons from nadh and fadh $ _2 $ travel exactly the same route . both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water . four electrons are required to reduce each molecule of o $ _2 $ , and two water molecules are formed in the process . overall , what does the electron transport chain do for the cell ? it has two important functions : regenerates electron carriers . nadh and fadh $ _2 $ pass their electrons to the electron transport chain , turning back into nad $ ^+ $ and fad . this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix . this gradient represents a stored form of energy , and , as we ’ ll see , it can be used to make atp . chemiosmosis complexes i , iii , and iv of the electron transport chain are proton pumps . as electrons move energetically downhill , the complexes capture the released energy and use it to pump h $ ^+ $ ions from the matrix to the intermembrane space . this pumping forms an electrochemical gradient across the inner mitochondrial membrane . the gradient is sometimes called the proton-motive force , and you can think of it as a form of stored energy , kind of like a battery . like many other ions , protons ca n't pass directly through the phospholipid bilayer of the membrane because its core is too hydrophobic . instead , h $ ^+ $ ions can move down their concentration gradient only with the help of channel proteins that form hydrophilic tunnels across the membrane . in the inner mitochondrial membrane , h $ ^+ $ ions have just one channel available : a membrane-spanning protein known as atp synthase . conceptually , atp synthase is a lot like a turbine in a hydroelectric power plant . instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis . more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis . what would happen to the energy stored in the proton gradient if it were n't used to synthesize atp or do other cellular work ? it would be released as heat , and interestingly enough , some types of cells deliberately use the proton gradient for heat generation rather than atp synthesis . this might seem wasteful , but it 's an important strategy for animals that need to keep warm . for instance , hibernating mammals ( such as bears ) have specialized cells known as brown fat cells . in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers . however , most current sources estimate that the maximum atp yield for a molecule of glucose is around 30-32 atp $ ^ { 2,3,4 } $ . this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation . based on a lot of experimental work , it appears that four h $ ^+ $ ions must flow back into the matrix through atp synthase to power the synthesis of one atp molecule . when electrons from nadh move through the transport chain , about 10 h $ ^+ $ ions are pumped from the matrix to the intermembrane space , so each nadh yields about 2.5 atp . electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i . instead , it must hand its electrons off to a molecular “ shuttle system ” that delivers them , through a series of steps , to the electron transport chain . some cells of your body have a shuttle system that delivers electrons to the transport chain via fadh $ _2 $ . in this case , only 3 atp are produced for the two nadh of glycolysis . other cells of your body have a shuttle system that delivers the electrons via nadh , resulting in the production of 5 atp . in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced . cellular respiration is a nexus for many different metabolic pathways in the cell , forming a network that ’ s larger than the glucose breakdown pathways alone . self-check questions
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in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy .
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how many protons does each proton pump , pump into the inner membrane space , each time an electron pair passes through it ?
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death . but have you ever wondered why that ’ s the case , or what exactly your body does with all that oxygen ? as it turns out , the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation , the final stage of cellular respiration . oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp . so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis . without enough atp , cells can ’ t carry out the reactions they need to function , and , after a long enough period of time , may even die . in this article , we 'll examine oxidative phosphorylation in depth , seeing how it provides most of the ready chemical energy ( atp ) used by the cells in your body . overview : oxidative phosphorylation the electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria . electrons are passed from one member of the transport chain to another in a series of redox reactions . energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ . reduced electron carriers ( nadh and fadh $ _2 $ ) from other steps of cellular respiration transfer their electrons to molecules near the beginning of the transport chain . in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy . some of the energy is used to pump h $ ^+ $ ions , moving them out of the matrix and into the intermembrane space . this pumping establishes an electrochemical gradient . splitting of oxygen to form water . at the end of the electron transport chain , electrons are transferred to molecular oxygen , which splits in half and takes up h $ ^+ $ to form water . gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane . as the electrons travel through the chain , they go from a higher to a lower energy level , moving from less electron-hungry to more electron-hungry molecules . energy is released in these “ downhill ” electron transfers , and several of the protein complexes use the released energy to pump protons from the mitochondrial matrix to the intermembrane space , forming a proton gradient . all of the electrons that enter the transport chain come from nadh and fadh $ _2 $ molecules produced during earlier stages of cellular respiration : glycolysis , pyruvate oxidation , and the citric acid cycle . nadh is very good at donating electrons in redox reactions ( that is , its electrons are at a high energy level ) , so it can transfer its electrons directly to complex i , turning back into nad $ ^+ $ . as electrons move through complex i in a series of redox reactions , energy is released , and the complex uses this energy to pump protons from the matrix into the intermembrane space . fadh $ _2 $ is not as good at donating electrons as nadh ( that is , its electrons are at a lower energy level ) , so it can not transfer its electrons to complex i . instead , it feeds them into the transport chain through complex ii , which does not pump protons across the membrane . because of this `` bypass , '' each fadh $ _2 $ molecule causes fewer protons to be pumped ( and contributes less to the proton gradient ) than an nadh . beyond the first two complexes , electrons from nadh and fadh $ _2 $ travel exactly the same route . both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water . four electrons are required to reduce each molecule of o $ _2 $ , and two water molecules are formed in the process . overall , what does the electron transport chain do for the cell ? it has two important functions : regenerates electron carriers . nadh and fadh $ _2 $ pass their electrons to the electron transport chain , turning back into nad $ ^+ $ and fad . this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix . this gradient represents a stored form of energy , and , as we ’ ll see , it can be used to make atp . chemiosmosis complexes i , iii , and iv of the electron transport chain are proton pumps . as electrons move energetically downhill , the complexes capture the released energy and use it to pump h $ ^+ $ ions from the matrix to the intermembrane space . this pumping forms an electrochemical gradient across the inner mitochondrial membrane . the gradient is sometimes called the proton-motive force , and you can think of it as a form of stored energy , kind of like a battery . like many other ions , protons ca n't pass directly through the phospholipid bilayer of the membrane because its core is too hydrophobic . instead , h $ ^+ $ ions can move down their concentration gradient only with the help of channel proteins that form hydrophilic tunnels across the membrane . in the inner mitochondrial membrane , h $ ^+ $ ions have just one channel available : a membrane-spanning protein known as atp synthase . conceptually , atp synthase is a lot like a turbine in a hydroelectric power plant . instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis . more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis . what would happen to the energy stored in the proton gradient if it were n't used to synthesize atp or do other cellular work ? it would be released as heat , and interestingly enough , some types of cells deliberately use the proton gradient for heat generation rather than atp synthesis . this might seem wasteful , but it 's an important strategy for animals that need to keep warm . for instance , hibernating mammals ( such as bears ) have specialized cells known as brown fat cells . in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers . however , most current sources estimate that the maximum atp yield for a molecule of glucose is around 30-32 atp $ ^ { 2,3,4 } $ . this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation . based on a lot of experimental work , it appears that four h $ ^+ $ ions must flow back into the matrix through atp synthase to power the synthesis of one atp molecule . when electrons from nadh move through the transport chain , about 10 h $ ^+ $ ions are pumped from the matrix to the intermembrane space , so each nadh yields about 2.5 atp . electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i . instead , it must hand its electrons off to a molecular “ shuttle system ” that delivers them , through a series of steps , to the electron transport chain . some cells of your body have a shuttle system that delivers electrons to the transport chain via fadh $ _2 $ . in this case , only 3 atp are produced for the two nadh of glycolysis . other cells of your body have a shuttle system that delivers the electrons via nadh , resulting in the production of 5 atp . in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced . cellular respiration is a nexus for many different metabolic pathways in the cell , forming a network that ’ s larger than the glucose breakdown pathways alone . self-check questions
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energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ .
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what happens if oxidative phopsphorylation can not occur ?
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death . but have you ever wondered why that ’ s the case , or what exactly your body does with all that oxygen ? as it turns out , the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation , the final stage of cellular respiration . oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp . so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis . without enough atp , cells can ’ t carry out the reactions they need to function , and , after a long enough period of time , may even die . in this article , we 'll examine oxidative phosphorylation in depth , seeing how it provides most of the ready chemical energy ( atp ) used by the cells in your body . overview : oxidative phosphorylation the electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria . electrons are passed from one member of the transport chain to another in a series of redox reactions . energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ . reduced electron carriers ( nadh and fadh $ _2 $ ) from other steps of cellular respiration transfer their electrons to molecules near the beginning of the transport chain . in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy . some of the energy is used to pump h $ ^+ $ ions , moving them out of the matrix and into the intermembrane space . this pumping establishes an electrochemical gradient . splitting of oxygen to form water . at the end of the electron transport chain , electrons are transferred to molecular oxygen , which splits in half and takes up h $ ^+ $ to form water . gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane . as the electrons travel through the chain , they go from a higher to a lower energy level , moving from less electron-hungry to more electron-hungry molecules . energy is released in these “ downhill ” electron transfers , and several of the protein complexes use the released energy to pump protons from the mitochondrial matrix to the intermembrane space , forming a proton gradient . all of the electrons that enter the transport chain come from nadh and fadh $ _2 $ molecules produced during earlier stages of cellular respiration : glycolysis , pyruvate oxidation , and the citric acid cycle . nadh is very good at donating electrons in redox reactions ( that is , its electrons are at a high energy level ) , so it can transfer its electrons directly to complex i , turning back into nad $ ^+ $ . as electrons move through complex i in a series of redox reactions , energy is released , and the complex uses this energy to pump protons from the matrix into the intermembrane space . fadh $ _2 $ is not as good at donating electrons as nadh ( that is , its electrons are at a lower energy level ) , so it can not transfer its electrons to complex i . instead , it feeds them into the transport chain through complex ii , which does not pump protons across the membrane . because of this `` bypass , '' each fadh $ _2 $ molecule causes fewer protons to be pumped ( and contributes less to the proton gradient ) than an nadh . beyond the first two complexes , electrons from nadh and fadh $ _2 $ travel exactly the same route . both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water . four electrons are required to reduce each molecule of o $ _2 $ , and two water molecules are formed in the process . overall , what does the electron transport chain do for the cell ? it has two important functions : regenerates electron carriers . nadh and fadh $ _2 $ pass their electrons to the electron transport chain , turning back into nad $ ^+ $ and fad . this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix . this gradient represents a stored form of energy , and , as we ’ ll see , it can be used to make atp . chemiosmosis complexes i , iii , and iv of the electron transport chain are proton pumps . as electrons move energetically downhill , the complexes capture the released energy and use it to pump h $ ^+ $ ions from the matrix to the intermembrane space . this pumping forms an electrochemical gradient across the inner mitochondrial membrane . the gradient is sometimes called the proton-motive force , and you can think of it as a form of stored energy , kind of like a battery . like many other ions , protons ca n't pass directly through the phospholipid bilayer of the membrane because its core is too hydrophobic . instead , h $ ^+ $ ions can move down their concentration gradient only with the help of channel proteins that form hydrophilic tunnels across the membrane . in the inner mitochondrial membrane , h $ ^+ $ ions have just one channel available : a membrane-spanning protein known as atp synthase . conceptually , atp synthase is a lot like a turbine in a hydroelectric power plant . instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis . more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis . what would happen to the energy stored in the proton gradient if it were n't used to synthesize atp or do other cellular work ? it would be released as heat , and interestingly enough , some types of cells deliberately use the proton gradient for heat generation rather than atp synthesis . this might seem wasteful , but it 's an important strategy for animals that need to keep warm . for instance , hibernating mammals ( such as bears ) have specialized cells known as brown fat cells . in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers . however , most current sources estimate that the maximum atp yield for a molecule of glucose is around 30-32 atp $ ^ { 2,3,4 } $ . this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation . based on a lot of experimental work , it appears that four h $ ^+ $ ions must flow back into the matrix through atp synthase to power the synthesis of one atp molecule . when electrons from nadh move through the transport chain , about 10 h $ ^+ $ ions are pumped from the matrix to the intermembrane space , so each nadh yields about 2.5 atp . electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i . instead , it must hand its electrons off to a molecular “ shuttle system ” that delivers them , through a series of steps , to the electron transport chain . some cells of your body have a shuttle system that delivers electrons to the transport chain via fadh $ _2 $ . in this case , only 3 atp are produced for the two nadh of glycolysis . other cells of your body have a shuttle system that delivers the electrons via nadh , resulting in the production of 5 atp . in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced . cellular respiration is a nexus for many different metabolic pathways in the cell , forming a network that ’ s larger than the glucose breakdown pathways alone . self-check questions
|
more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis .
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are some of the 6 oxygen molecules being used somewhere else in the cellular respiration or is there something i 'm missing ?
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death . but have you ever wondered why that ’ s the case , or what exactly your body does with all that oxygen ? as it turns out , the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation , the final stage of cellular respiration . oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp . so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis . without enough atp , cells can ’ t carry out the reactions they need to function , and , after a long enough period of time , may even die . in this article , we 'll examine oxidative phosphorylation in depth , seeing how it provides most of the ready chemical energy ( atp ) used by the cells in your body . overview : oxidative phosphorylation the electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria . electrons are passed from one member of the transport chain to another in a series of redox reactions . energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ . reduced electron carriers ( nadh and fadh $ _2 $ ) from other steps of cellular respiration transfer their electrons to molecules near the beginning of the transport chain . in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy . some of the energy is used to pump h $ ^+ $ ions , moving them out of the matrix and into the intermembrane space . this pumping establishes an electrochemical gradient . splitting of oxygen to form water . at the end of the electron transport chain , electrons are transferred to molecular oxygen , which splits in half and takes up h $ ^+ $ to form water . gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane . as the electrons travel through the chain , they go from a higher to a lower energy level , moving from less electron-hungry to more electron-hungry molecules . energy is released in these “ downhill ” electron transfers , and several of the protein complexes use the released energy to pump protons from the mitochondrial matrix to the intermembrane space , forming a proton gradient . all of the electrons that enter the transport chain come from nadh and fadh $ _2 $ molecules produced during earlier stages of cellular respiration : glycolysis , pyruvate oxidation , and the citric acid cycle . nadh is very good at donating electrons in redox reactions ( that is , its electrons are at a high energy level ) , so it can transfer its electrons directly to complex i , turning back into nad $ ^+ $ . as electrons move through complex i in a series of redox reactions , energy is released , and the complex uses this energy to pump protons from the matrix into the intermembrane space . fadh $ _2 $ is not as good at donating electrons as nadh ( that is , its electrons are at a lower energy level ) , so it can not transfer its electrons to complex i . instead , it feeds them into the transport chain through complex ii , which does not pump protons across the membrane . because of this `` bypass , '' each fadh $ _2 $ molecule causes fewer protons to be pumped ( and contributes less to the proton gradient ) than an nadh . beyond the first two complexes , electrons from nadh and fadh $ _2 $ travel exactly the same route . both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water . four electrons are required to reduce each molecule of o $ _2 $ , and two water molecules are formed in the process . overall , what does the electron transport chain do for the cell ? it has two important functions : regenerates electron carriers . nadh and fadh $ _2 $ pass their electrons to the electron transport chain , turning back into nad $ ^+ $ and fad . this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix . this gradient represents a stored form of energy , and , as we ’ ll see , it can be used to make atp . chemiosmosis complexes i , iii , and iv of the electron transport chain are proton pumps . as electrons move energetically downhill , the complexes capture the released energy and use it to pump h $ ^+ $ ions from the matrix to the intermembrane space . this pumping forms an electrochemical gradient across the inner mitochondrial membrane . the gradient is sometimes called the proton-motive force , and you can think of it as a form of stored energy , kind of like a battery . like many other ions , protons ca n't pass directly through the phospholipid bilayer of the membrane because its core is too hydrophobic . instead , h $ ^+ $ ions can move down their concentration gradient only with the help of channel proteins that form hydrophilic tunnels across the membrane . in the inner mitochondrial membrane , h $ ^+ $ ions have just one channel available : a membrane-spanning protein known as atp synthase . conceptually , atp synthase is a lot like a turbine in a hydroelectric power plant . instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis . more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis . what would happen to the energy stored in the proton gradient if it were n't used to synthesize atp or do other cellular work ? it would be released as heat , and interestingly enough , some types of cells deliberately use the proton gradient for heat generation rather than atp synthesis . this might seem wasteful , but it 's an important strategy for animals that need to keep warm . for instance , hibernating mammals ( such as bears ) have specialized cells known as brown fat cells . in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers . however , most current sources estimate that the maximum atp yield for a molecule of glucose is around 30-32 atp $ ^ { 2,3,4 } $ . this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation . based on a lot of experimental work , it appears that four h $ ^+ $ ions must flow back into the matrix through atp synthase to power the synthesis of one atp molecule . when electrons from nadh move through the transport chain , about 10 h $ ^+ $ ions are pumped from the matrix to the intermembrane space , so each nadh yields about 2.5 atp . electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i . instead , it must hand its electrons off to a molecular “ shuttle system ” that delivers them , through a series of steps , to the electron transport chain . some cells of your body have a shuttle system that delivers electrons to the transport chain via fadh $ _2 $ . in this case , only 3 atp are produced for the two nadh of glycolysis . other cells of your body have a shuttle system that delivers the electrons via nadh , resulting in the production of 5 atp . in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced . cellular respiration is a nexus for many different metabolic pathways in the cell , forming a network that ’ s larger than the glucose breakdown pathways alone . self-check questions
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this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix .
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are there any other ways a a proton gradient can be used in the mitochondria ?
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death . but have you ever wondered why that ’ s the case , or what exactly your body does with all that oxygen ? as it turns out , the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation , the final stage of cellular respiration . oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp . so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis . without enough atp , cells can ’ t carry out the reactions they need to function , and , after a long enough period of time , may even die . in this article , we 'll examine oxidative phosphorylation in depth , seeing how it provides most of the ready chemical energy ( atp ) used by the cells in your body . overview : oxidative phosphorylation the electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria . electrons are passed from one member of the transport chain to another in a series of redox reactions . energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ . reduced electron carriers ( nadh and fadh $ _2 $ ) from other steps of cellular respiration transfer their electrons to molecules near the beginning of the transport chain . in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy . some of the energy is used to pump h $ ^+ $ ions , moving them out of the matrix and into the intermembrane space . this pumping establishes an electrochemical gradient . splitting of oxygen to form water . at the end of the electron transport chain , electrons are transferred to molecular oxygen , which splits in half and takes up h $ ^+ $ to form water . gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane . as the electrons travel through the chain , they go from a higher to a lower energy level , moving from less electron-hungry to more electron-hungry molecules . energy is released in these “ downhill ” electron transfers , and several of the protein complexes use the released energy to pump protons from the mitochondrial matrix to the intermembrane space , forming a proton gradient . all of the electrons that enter the transport chain come from nadh and fadh $ _2 $ molecules produced during earlier stages of cellular respiration : glycolysis , pyruvate oxidation , and the citric acid cycle . nadh is very good at donating electrons in redox reactions ( that is , its electrons are at a high energy level ) , so it can transfer its electrons directly to complex i , turning back into nad $ ^+ $ . as electrons move through complex i in a series of redox reactions , energy is released , and the complex uses this energy to pump protons from the matrix into the intermembrane space . fadh $ _2 $ is not as good at donating electrons as nadh ( that is , its electrons are at a lower energy level ) , so it can not transfer its electrons to complex i . instead , it feeds them into the transport chain through complex ii , which does not pump protons across the membrane . because of this `` bypass , '' each fadh $ _2 $ molecule causes fewer protons to be pumped ( and contributes less to the proton gradient ) than an nadh . beyond the first two complexes , electrons from nadh and fadh $ _2 $ travel exactly the same route . both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water . four electrons are required to reduce each molecule of o $ _2 $ , and two water molecules are formed in the process . overall , what does the electron transport chain do for the cell ? it has two important functions : regenerates electron carriers . nadh and fadh $ _2 $ pass their electrons to the electron transport chain , turning back into nad $ ^+ $ and fad . this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix . this gradient represents a stored form of energy , and , as we ’ ll see , it can be used to make atp . chemiosmosis complexes i , iii , and iv of the electron transport chain are proton pumps . as electrons move energetically downhill , the complexes capture the released energy and use it to pump h $ ^+ $ ions from the matrix to the intermembrane space . this pumping forms an electrochemical gradient across the inner mitochondrial membrane . the gradient is sometimes called the proton-motive force , and you can think of it as a form of stored energy , kind of like a battery . like many other ions , protons ca n't pass directly through the phospholipid bilayer of the membrane because its core is too hydrophobic . instead , h $ ^+ $ ions can move down their concentration gradient only with the help of channel proteins that form hydrophilic tunnels across the membrane . in the inner mitochondrial membrane , h $ ^+ $ ions have just one channel available : a membrane-spanning protein known as atp synthase . conceptually , atp synthase is a lot like a turbine in a hydroelectric power plant . instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis . more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis . what would happen to the energy stored in the proton gradient if it were n't used to synthesize atp or do other cellular work ? it would be released as heat , and interestingly enough , some types of cells deliberately use the proton gradient for heat generation rather than atp synthesis . this might seem wasteful , but it 's an important strategy for animals that need to keep warm . for instance , hibernating mammals ( such as bears ) have specialized cells known as brown fat cells . in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers . however , most current sources estimate that the maximum atp yield for a molecule of glucose is around 30-32 atp $ ^ { 2,3,4 } $ . this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation . based on a lot of experimental work , it appears that four h $ ^+ $ ions must flow back into the matrix through atp synthase to power the synthesis of one atp molecule . when electrons from nadh move through the transport chain , about 10 h $ ^+ $ ions are pumped from the matrix to the intermembrane space , so each nadh yields about 2.5 atp . electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i . instead , it must hand its electrons off to a molecular “ shuttle system ” that delivers them , through a series of steps , to the electron transport chain . some cells of your body have a shuttle system that delivers electrons to the transport chain via fadh $ _2 $ . in this case , only 3 atp are produced for the two nadh of glycolysis . other cells of your body have a shuttle system that delivers the electrons via nadh , resulting in the production of 5 atp . in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced . cellular respiration is a nexus for many different metabolic pathways in the cell , forming a network that ’ s larger than the glucose breakdown pathways alone . self-check questions
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instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis .
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however in the last step where you describe the atp-synthase you all of the sudden have adp + p. i dont understand where that adp is coming from as youve only oxidized your nadh ?
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death . but have you ever wondered why that ’ s the case , or what exactly your body does with all that oxygen ? as it turns out , the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation , the final stage of cellular respiration . oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp . so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis . without enough atp , cells can ’ t carry out the reactions they need to function , and , after a long enough period of time , may even die . in this article , we 'll examine oxidative phosphorylation in depth , seeing how it provides most of the ready chemical energy ( atp ) used by the cells in your body . overview : oxidative phosphorylation the electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria . electrons are passed from one member of the transport chain to another in a series of redox reactions . energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ . reduced electron carriers ( nadh and fadh $ _2 $ ) from other steps of cellular respiration transfer their electrons to molecules near the beginning of the transport chain . in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy . some of the energy is used to pump h $ ^+ $ ions , moving them out of the matrix and into the intermembrane space . this pumping establishes an electrochemical gradient . splitting of oxygen to form water . at the end of the electron transport chain , electrons are transferred to molecular oxygen , which splits in half and takes up h $ ^+ $ to form water . gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane . as the electrons travel through the chain , they go from a higher to a lower energy level , moving from less electron-hungry to more electron-hungry molecules . energy is released in these “ downhill ” electron transfers , and several of the protein complexes use the released energy to pump protons from the mitochondrial matrix to the intermembrane space , forming a proton gradient . all of the electrons that enter the transport chain come from nadh and fadh $ _2 $ molecules produced during earlier stages of cellular respiration : glycolysis , pyruvate oxidation , and the citric acid cycle . nadh is very good at donating electrons in redox reactions ( that is , its electrons are at a high energy level ) , so it can transfer its electrons directly to complex i , turning back into nad $ ^+ $ . as electrons move through complex i in a series of redox reactions , energy is released , and the complex uses this energy to pump protons from the matrix into the intermembrane space . fadh $ _2 $ is not as good at donating electrons as nadh ( that is , its electrons are at a lower energy level ) , so it can not transfer its electrons to complex i . instead , it feeds them into the transport chain through complex ii , which does not pump protons across the membrane . because of this `` bypass , '' each fadh $ _2 $ molecule causes fewer protons to be pumped ( and contributes less to the proton gradient ) than an nadh . beyond the first two complexes , electrons from nadh and fadh $ _2 $ travel exactly the same route . both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water . four electrons are required to reduce each molecule of o $ _2 $ , and two water molecules are formed in the process . overall , what does the electron transport chain do for the cell ? it has two important functions : regenerates electron carriers . nadh and fadh $ _2 $ pass their electrons to the electron transport chain , turning back into nad $ ^+ $ and fad . this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix . this gradient represents a stored form of energy , and , as we ’ ll see , it can be used to make atp . chemiosmosis complexes i , iii , and iv of the electron transport chain are proton pumps . as electrons move energetically downhill , the complexes capture the released energy and use it to pump h $ ^+ $ ions from the matrix to the intermembrane space . this pumping forms an electrochemical gradient across the inner mitochondrial membrane . the gradient is sometimes called the proton-motive force , and you can think of it as a form of stored energy , kind of like a battery . like many other ions , protons ca n't pass directly through the phospholipid bilayer of the membrane because its core is too hydrophobic . instead , h $ ^+ $ ions can move down their concentration gradient only with the help of channel proteins that form hydrophilic tunnels across the membrane . in the inner mitochondrial membrane , h $ ^+ $ ions have just one channel available : a membrane-spanning protein known as atp synthase . conceptually , atp synthase is a lot like a turbine in a hydroelectric power plant . instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis . more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis . what would happen to the energy stored in the proton gradient if it were n't used to synthesize atp or do other cellular work ? it would be released as heat , and interestingly enough , some types of cells deliberately use the proton gradient for heat generation rather than atp synthesis . this might seem wasteful , but it 's an important strategy for animals that need to keep warm . for instance , hibernating mammals ( such as bears ) have specialized cells known as brown fat cells . in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers . however , most current sources estimate that the maximum atp yield for a molecule of glucose is around 30-32 atp $ ^ { 2,3,4 } $ . this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation . based on a lot of experimental work , it appears that four h $ ^+ $ ions must flow back into the matrix through atp synthase to power the synthesis of one atp molecule . when electrons from nadh move through the transport chain , about 10 h $ ^+ $ ions are pumped from the matrix to the intermembrane space , so each nadh yields about 2.5 atp . electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i . instead , it must hand its electrons off to a molecular “ shuttle system ” that delivers them , through a series of steps , to the electron transport chain . some cells of your body have a shuttle system that delivers electrons to the transport chain via fadh $ _2 $ . in this case , only 3 atp are produced for the two nadh of glycolysis . other cells of your body have a shuttle system that delivers the electrons via nadh , resulting in the production of 5 atp . in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced . cellular respiration is a nexus for many different metabolic pathways in the cell , forming a network that ’ s larger than the glucose breakdown pathways alone . self-check questions
|
the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane .
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how many membrane proteins are there in the etc ?
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death . but have you ever wondered why that ’ s the case , or what exactly your body does with all that oxygen ? as it turns out , the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation , the final stage of cellular respiration . oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp . so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis . without enough atp , cells can ’ t carry out the reactions they need to function , and , after a long enough period of time , may even die . in this article , we 'll examine oxidative phosphorylation in depth , seeing how it provides most of the ready chemical energy ( atp ) used by the cells in your body . overview : oxidative phosphorylation the electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria . electrons are passed from one member of the transport chain to another in a series of redox reactions . energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ . reduced electron carriers ( nadh and fadh $ _2 $ ) from other steps of cellular respiration transfer their electrons to molecules near the beginning of the transport chain . in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy . some of the energy is used to pump h $ ^+ $ ions , moving them out of the matrix and into the intermembrane space . this pumping establishes an electrochemical gradient . splitting of oxygen to form water . at the end of the electron transport chain , electrons are transferred to molecular oxygen , which splits in half and takes up h $ ^+ $ to form water . gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane . as the electrons travel through the chain , they go from a higher to a lower energy level , moving from less electron-hungry to more electron-hungry molecules . energy is released in these “ downhill ” electron transfers , and several of the protein complexes use the released energy to pump protons from the mitochondrial matrix to the intermembrane space , forming a proton gradient . all of the electrons that enter the transport chain come from nadh and fadh $ _2 $ molecules produced during earlier stages of cellular respiration : glycolysis , pyruvate oxidation , and the citric acid cycle . nadh is very good at donating electrons in redox reactions ( that is , its electrons are at a high energy level ) , so it can transfer its electrons directly to complex i , turning back into nad $ ^+ $ . as electrons move through complex i in a series of redox reactions , energy is released , and the complex uses this energy to pump protons from the matrix into the intermembrane space . fadh $ _2 $ is not as good at donating electrons as nadh ( that is , its electrons are at a lower energy level ) , so it can not transfer its electrons to complex i . instead , it feeds them into the transport chain through complex ii , which does not pump protons across the membrane . because of this `` bypass , '' each fadh $ _2 $ molecule causes fewer protons to be pumped ( and contributes less to the proton gradient ) than an nadh . beyond the first two complexes , electrons from nadh and fadh $ _2 $ travel exactly the same route . both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water . four electrons are required to reduce each molecule of o $ _2 $ , and two water molecules are formed in the process . overall , what does the electron transport chain do for the cell ? it has two important functions : regenerates electron carriers . nadh and fadh $ _2 $ pass their electrons to the electron transport chain , turning back into nad $ ^+ $ and fad . this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix . this gradient represents a stored form of energy , and , as we ’ ll see , it can be used to make atp . chemiosmosis complexes i , iii , and iv of the electron transport chain are proton pumps . as electrons move energetically downhill , the complexes capture the released energy and use it to pump h $ ^+ $ ions from the matrix to the intermembrane space . this pumping forms an electrochemical gradient across the inner mitochondrial membrane . the gradient is sometimes called the proton-motive force , and you can think of it as a form of stored energy , kind of like a battery . like many other ions , protons ca n't pass directly through the phospholipid bilayer of the membrane because its core is too hydrophobic . instead , h $ ^+ $ ions can move down their concentration gradient only with the help of channel proteins that form hydrophilic tunnels across the membrane . in the inner mitochondrial membrane , h $ ^+ $ ions have just one channel available : a membrane-spanning protein known as atp synthase . conceptually , atp synthase is a lot like a turbine in a hydroelectric power plant . instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis . more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis . what would happen to the energy stored in the proton gradient if it were n't used to synthesize atp or do other cellular work ? it would be released as heat , and interestingly enough , some types of cells deliberately use the proton gradient for heat generation rather than atp synthesis . this might seem wasteful , but it 's an important strategy for animals that need to keep warm . for instance , hibernating mammals ( such as bears ) have specialized cells known as brown fat cells . in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers . however , most current sources estimate that the maximum atp yield for a molecule of glucose is around 30-32 atp $ ^ { 2,3,4 } $ . this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation . based on a lot of experimental work , it appears that four h $ ^+ $ ions must flow back into the matrix through atp synthase to power the synthesis of one atp molecule . when electrons from nadh move through the transport chain , about 10 h $ ^+ $ ions are pumped from the matrix to the intermembrane space , so each nadh yields about 2.5 atp . electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i . instead , it must hand its electrons off to a molecular “ shuttle system ” that delivers them , through a series of steps , to the electron transport chain . some cells of your body have a shuttle system that delivers electrons to the transport chain via fadh $ _2 $ . in this case , only 3 atp are produced for the two nadh of glycolysis . other cells of your body have a shuttle system that delivers the electrons via nadh , resulting in the production of 5 atp . in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced . cellular respiration is a nexus for many different metabolic pathways in the cell , forming a network that ’ s larger than the glucose breakdown pathways alone . self-check questions
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as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water .
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where do the h+ come from that get pumped into the inter-membrane space to make a gradient ?
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death . but have you ever wondered why that ’ s the case , or what exactly your body does with all that oxygen ? as it turns out , the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation , the final stage of cellular respiration . oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp . so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis . without enough atp , cells can ’ t carry out the reactions they need to function , and , after a long enough period of time , may even die . in this article , we 'll examine oxidative phosphorylation in depth , seeing how it provides most of the ready chemical energy ( atp ) used by the cells in your body . overview : oxidative phosphorylation the electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria . electrons are passed from one member of the transport chain to another in a series of redox reactions . energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ . reduced electron carriers ( nadh and fadh $ _2 $ ) from other steps of cellular respiration transfer their electrons to molecules near the beginning of the transport chain . in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy . some of the energy is used to pump h $ ^+ $ ions , moving them out of the matrix and into the intermembrane space . this pumping establishes an electrochemical gradient . splitting of oxygen to form water . at the end of the electron transport chain , electrons are transferred to molecular oxygen , which splits in half and takes up h $ ^+ $ to form water . gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane . as the electrons travel through the chain , they go from a higher to a lower energy level , moving from less electron-hungry to more electron-hungry molecules . energy is released in these “ downhill ” electron transfers , and several of the protein complexes use the released energy to pump protons from the mitochondrial matrix to the intermembrane space , forming a proton gradient . all of the electrons that enter the transport chain come from nadh and fadh $ _2 $ molecules produced during earlier stages of cellular respiration : glycolysis , pyruvate oxidation , and the citric acid cycle . nadh is very good at donating electrons in redox reactions ( that is , its electrons are at a high energy level ) , so it can transfer its electrons directly to complex i , turning back into nad $ ^+ $ . as electrons move through complex i in a series of redox reactions , energy is released , and the complex uses this energy to pump protons from the matrix into the intermembrane space . fadh $ _2 $ is not as good at donating electrons as nadh ( that is , its electrons are at a lower energy level ) , so it can not transfer its electrons to complex i . instead , it feeds them into the transport chain through complex ii , which does not pump protons across the membrane . because of this `` bypass , '' each fadh $ _2 $ molecule causes fewer protons to be pumped ( and contributes less to the proton gradient ) than an nadh . beyond the first two complexes , electrons from nadh and fadh $ _2 $ travel exactly the same route . both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water . four electrons are required to reduce each molecule of o $ _2 $ , and two water molecules are formed in the process . overall , what does the electron transport chain do for the cell ? it has two important functions : regenerates electron carriers . nadh and fadh $ _2 $ pass their electrons to the electron transport chain , turning back into nad $ ^+ $ and fad . this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix . this gradient represents a stored form of energy , and , as we ’ ll see , it can be used to make atp . chemiosmosis complexes i , iii , and iv of the electron transport chain are proton pumps . as electrons move energetically downhill , the complexes capture the released energy and use it to pump h $ ^+ $ ions from the matrix to the intermembrane space . this pumping forms an electrochemical gradient across the inner mitochondrial membrane . the gradient is sometimes called the proton-motive force , and you can think of it as a form of stored energy , kind of like a battery . like many other ions , protons ca n't pass directly through the phospholipid bilayer of the membrane because its core is too hydrophobic . instead , h $ ^+ $ ions can move down their concentration gradient only with the help of channel proteins that form hydrophilic tunnels across the membrane . in the inner mitochondrial membrane , h $ ^+ $ ions have just one channel available : a membrane-spanning protein known as atp synthase . conceptually , atp synthase is a lot like a turbine in a hydroelectric power plant . instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis . more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis . what would happen to the energy stored in the proton gradient if it were n't used to synthesize atp or do other cellular work ? it would be released as heat , and interestingly enough , some types of cells deliberately use the proton gradient for heat generation rather than atp synthesis . this might seem wasteful , but it 's an important strategy for animals that need to keep warm . for instance , hibernating mammals ( such as bears ) have specialized cells known as brown fat cells . in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers . however , most current sources estimate that the maximum atp yield for a molecule of glucose is around 30-32 atp $ ^ { 2,3,4 } $ . this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation . based on a lot of experimental work , it appears that four h $ ^+ $ ions must flow back into the matrix through atp synthase to power the synthesis of one atp molecule . when electrons from nadh move through the transport chain , about 10 h $ ^+ $ ions are pumped from the matrix to the intermembrane space , so each nadh yields about 2.5 atp . electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i . instead , it must hand its electrons off to a molecular “ shuttle system ” that delivers them , through a series of steps , to the electron transport chain . some cells of your body have a shuttle system that delivers electrons to the transport chain via fadh $ _2 $ . in this case , only 3 atp are produced for the two nadh of glycolysis . other cells of your body have a shuttle system that delivers the electrons via nadh , resulting in the production of 5 atp . in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced . cellular respiration is a nexus for many different metabolic pathways in the cell , forming a network that ’ s larger than the glucose breakdown pathways alone . self-check questions
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gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below .
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if the h+ ions are utilised in forming water where do the other h+ ions come from to pass through the atp synthase ?
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death . but have you ever wondered why that ’ s the case , or what exactly your body does with all that oxygen ? as it turns out , the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation , the final stage of cellular respiration . oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp . so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis . without enough atp , cells can ’ t carry out the reactions they need to function , and , after a long enough period of time , may even die . in this article , we 'll examine oxidative phosphorylation in depth , seeing how it provides most of the ready chemical energy ( atp ) used by the cells in your body . overview : oxidative phosphorylation the electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria . electrons are passed from one member of the transport chain to another in a series of redox reactions . energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ . reduced electron carriers ( nadh and fadh $ _2 $ ) from other steps of cellular respiration transfer their electrons to molecules near the beginning of the transport chain . in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy . some of the energy is used to pump h $ ^+ $ ions , moving them out of the matrix and into the intermembrane space . this pumping establishes an electrochemical gradient . splitting of oxygen to form water . at the end of the electron transport chain , electrons are transferred to molecular oxygen , which splits in half and takes up h $ ^+ $ to form water . gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane . as the electrons travel through the chain , they go from a higher to a lower energy level , moving from less electron-hungry to more electron-hungry molecules . energy is released in these “ downhill ” electron transfers , and several of the protein complexes use the released energy to pump protons from the mitochondrial matrix to the intermembrane space , forming a proton gradient . all of the electrons that enter the transport chain come from nadh and fadh $ _2 $ molecules produced during earlier stages of cellular respiration : glycolysis , pyruvate oxidation , and the citric acid cycle . nadh is very good at donating electrons in redox reactions ( that is , its electrons are at a high energy level ) , so it can transfer its electrons directly to complex i , turning back into nad $ ^+ $ . as electrons move through complex i in a series of redox reactions , energy is released , and the complex uses this energy to pump protons from the matrix into the intermembrane space . fadh $ _2 $ is not as good at donating electrons as nadh ( that is , its electrons are at a lower energy level ) , so it can not transfer its electrons to complex i . instead , it feeds them into the transport chain through complex ii , which does not pump protons across the membrane . because of this `` bypass , '' each fadh $ _2 $ molecule causes fewer protons to be pumped ( and contributes less to the proton gradient ) than an nadh . beyond the first two complexes , electrons from nadh and fadh $ _2 $ travel exactly the same route . both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water . four electrons are required to reduce each molecule of o $ _2 $ , and two water molecules are formed in the process . overall , what does the electron transport chain do for the cell ? it has two important functions : regenerates electron carriers . nadh and fadh $ _2 $ pass their electrons to the electron transport chain , turning back into nad $ ^+ $ and fad . this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix . this gradient represents a stored form of energy , and , as we ’ ll see , it can be used to make atp . chemiosmosis complexes i , iii , and iv of the electron transport chain are proton pumps . as electrons move energetically downhill , the complexes capture the released energy and use it to pump h $ ^+ $ ions from the matrix to the intermembrane space . this pumping forms an electrochemical gradient across the inner mitochondrial membrane . the gradient is sometimes called the proton-motive force , and you can think of it as a form of stored energy , kind of like a battery . like many other ions , protons ca n't pass directly through the phospholipid bilayer of the membrane because its core is too hydrophobic . instead , h $ ^+ $ ions can move down their concentration gradient only with the help of channel proteins that form hydrophilic tunnels across the membrane . in the inner mitochondrial membrane , h $ ^+ $ ions have just one channel available : a membrane-spanning protein known as atp synthase . conceptually , atp synthase is a lot like a turbine in a hydroelectric power plant . instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis . more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis . what would happen to the energy stored in the proton gradient if it were n't used to synthesize atp or do other cellular work ? it would be released as heat , and interestingly enough , some types of cells deliberately use the proton gradient for heat generation rather than atp synthesis . this might seem wasteful , but it 's an important strategy for animals that need to keep warm . for instance , hibernating mammals ( such as bears ) have specialized cells known as brown fat cells . in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers . however , most current sources estimate that the maximum atp yield for a molecule of glucose is around 30-32 atp $ ^ { 2,3,4 } $ . this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation . based on a lot of experimental work , it appears that four h $ ^+ $ ions must flow back into the matrix through atp synthase to power the synthesis of one atp molecule . when electrons from nadh move through the transport chain , about 10 h $ ^+ $ ions are pumped from the matrix to the intermembrane space , so each nadh yields about 2.5 atp . electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i . instead , it must hand its electrons off to a molecular “ shuttle system ” that delivers them , through a series of steps , to the electron transport chain . some cells of your body have a shuttle system that delivers electrons to the transport chain via fadh $ _2 $ . in this case , only 3 atp are produced for the two nadh of glycolysis . other cells of your body have a shuttle system that delivers the electrons via nadh , resulting in the production of 5 atp . in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced . cellular respiration is a nexus for many different metabolic pathways in the cell , forming a network that ’ s larger than the glucose breakdown pathways alone . self-check questions
|
electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i .
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btw is atp synthase an enzymatic complex or is it just a single enzyme ?
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why do we need oxygen ? you , like many other organisms , need oxygen to live . as you know if you ’ ve ever tried to hold your breath for too long , lack of oxygen can make you feel dizzy or even black out , and prolonged lack of oxygen can even cause death . but have you ever wondered why that ’ s the case , or what exactly your body does with all that oxygen ? as it turns out , the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation , the final stage of cellular respiration . oxidative phosphorylation is made up of two closely connected components : the electron transport chain and chemiosmosis . in the electron transport chain , electrons are passed from one molecule to another , and energy released in these electron transfers is used to form an electrochemical gradient . in chemiosmosis , the energy stored in the gradient is used to make atp . so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis . without enough atp , cells can ’ t carry out the reactions they need to function , and , after a long enough period of time , may even die . in this article , we 'll examine oxidative phosphorylation in depth , seeing how it provides most of the ready chemical energy ( atp ) used by the cells in your body . overview : oxidative phosphorylation the electron transport chain is a series of proteins and organic molecules found in the inner membrane of the mitochondria . electrons are passed from one member of the transport chain to another in a series of redox reactions . energy released in these reactions is captured as a proton gradient , which is then used to make atp in a process called chemiosmosis . together , the electron transport chain and chemiosmosis make up oxidative phosphorylation . the key steps of this process , shown in simplified form in the diagram above , include : delivery of electrons by nadh and fadh $ _2 $ . reduced electron carriers ( nadh and fadh $ _2 $ ) from other steps of cellular respiration transfer their electrons to molecules near the beginning of the transport chain . in the process , they turn back into nad $ ^+ $ and fad , which can be reused in other steps of cellular respiration . electron transfer and proton pumping . as electrons are passed down the chain , they move from a higher to a lower energy level , releasing energy . some of the energy is used to pump h $ ^+ $ ions , moving them out of the matrix and into the intermembrane space . this pumping establishes an electrochemical gradient . splitting of oxygen to form water . at the end of the electron transport chain , electrons are transferred to molecular oxygen , which splits in half and takes up h $ ^+ $ to form water . gradient-driven synthesis of atp . as h $ ^+ $ ions flow down their gradient and back into the matrix , they pass through an enzyme called atp synthase , which harnesses the flow of protons to synthesize atp . we 'll look more closely at both the electron transport chain and chemiosmosis in the sections below . the electron transport chain the electron transport chain is a collection of membrane-embedded proteins and organic molecules , most of them organized into four large complexes labeled i to iv . in eukaryotes , many copies of these molecules are found in the inner mitochondrial membrane . in prokaryotes , the electron transport chain components are found in the plasma membrane . as the electrons travel through the chain , they go from a higher to a lower energy level , moving from less electron-hungry to more electron-hungry molecules . energy is released in these “ downhill ” electron transfers , and several of the protein complexes use the released energy to pump protons from the mitochondrial matrix to the intermembrane space , forming a proton gradient . all of the electrons that enter the transport chain come from nadh and fadh $ _2 $ molecules produced during earlier stages of cellular respiration : glycolysis , pyruvate oxidation , and the citric acid cycle . nadh is very good at donating electrons in redox reactions ( that is , its electrons are at a high energy level ) , so it can transfer its electrons directly to complex i , turning back into nad $ ^+ $ . as electrons move through complex i in a series of redox reactions , energy is released , and the complex uses this energy to pump protons from the matrix into the intermembrane space . fadh $ _2 $ is not as good at donating electrons as nadh ( that is , its electrons are at a lower energy level ) , so it can not transfer its electrons to complex i . instead , it feeds them into the transport chain through complex ii , which does not pump protons across the membrane . because of this `` bypass , '' each fadh $ _2 $ molecule causes fewer protons to be pumped ( and contributes less to the proton gradient ) than an nadh . beyond the first two complexes , electrons from nadh and fadh $ _2 $ travel exactly the same route . both complex i and complex ii pass their electrons to a small , mobile electron carrier called ubiquinone ( q ) , which is reduced to form qh $ _2 $ and travels through the membrane , delivering the electrons to complex iii . as electrons move through complex iii , more h $ ^+ $ ions are pumped across the membrane , and the electrons are ultimately delivered to another mobile carrier called cytochrome c ( cyt c ) . cyt c carries the electrons to complex iv , where a final batch of h $ ^+ $ ions is pumped across the membrane . complex iv passes the electrons to o $ _2 $ , which splits into two oxygen atoms and accepts protons from the matrix to form water . four electrons are required to reduce each molecule of o $ _2 $ , and two water molecules are formed in the process . overall , what does the electron transport chain do for the cell ? it has two important functions : regenerates electron carriers . nadh and fadh $ _2 $ pass their electrons to the electron transport chain , turning back into nad $ ^+ $ and fad . this is important because the oxidized forms of these electron carriers are used in glycolysis and the citric acid cycle and must be available to keep these processes running . makes a proton gradient . the transport chain builds a proton gradient across the inner mitochondrial membrane , with a higher concentration of h $ ^+ $ in the intermembrane space and a lower concentration in the matrix . this gradient represents a stored form of energy , and , as we ’ ll see , it can be used to make atp . chemiosmosis complexes i , iii , and iv of the electron transport chain are proton pumps . as electrons move energetically downhill , the complexes capture the released energy and use it to pump h $ ^+ $ ions from the matrix to the intermembrane space . this pumping forms an electrochemical gradient across the inner mitochondrial membrane . the gradient is sometimes called the proton-motive force , and you can think of it as a form of stored energy , kind of like a battery . like many other ions , protons ca n't pass directly through the phospholipid bilayer of the membrane because its core is too hydrophobic . instead , h $ ^+ $ ions can move down their concentration gradient only with the help of channel proteins that form hydrophilic tunnels across the membrane . in the inner mitochondrial membrane , h $ ^+ $ ions have just one channel available : a membrane-spanning protein known as atp synthase . conceptually , atp synthase is a lot like a turbine in a hydroelectric power plant . instead of being turned by water , it ’ s turned by the flow of h $ ^+ $ ions moving down their electrochemical gradient . as atp synthase turns , it catalyzes the addition of a phosphate to adp , capturing energy from the proton gradient as atp . this process , in which energy from a proton gradient is used to make atp , is called chemiosmosis . more broadly , chemiosmosis can refer to any process in which energy stored in a proton gradient is used to do work . although chemiosmosis accounts for over 80 % of atp made during glucose breakdown in cellular respiration , it ’ s not unique to cellular respiration . for instance , chemiosmosis is also involved in the light reactions of photosynthesis . what would happen to the energy stored in the proton gradient if it were n't used to synthesize atp or do other cellular work ? it would be released as heat , and interestingly enough , some types of cells deliberately use the proton gradient for heat generation rather than atp synthesis . this might seem wasteful , but it 's an important strategy for animals that need to keep warm . for instance , hibernating mammals ( such as bears ) have specialized cells known as brown fat cells . in the brown fat cells , uncoupling proteins are produced and inserted into the inner mitochondrial membrane . these proteins are simply channels that allow protons to pass from the intermembrane space to the matrix without traveling through atp synthase . by providing an alternate route for protons to flow back into the matrix , the uncoupling proteins allow the energy of the gradient to be dissipated as heat . atp yield how many atp do we get per glucose in cellular respiration ? if you look in different books , or ask different professors , you 'll probably get slightly different answers . however , most current sources estimate that the maximum atp yield for a molecule of glucose is around 30-32 atp $ ^ { 2,3,4 } $ . this range is lower than previous estimates because it accounts for the necessary transport of adp into , and atp out of , the mitochondrion . where does the figure of 30-32 atp come from ? two net atp are made in glycolysis , and another two atp ( or energetically equivalent gtp ) are made in the citric acid cycle . beyond those four , the remaining atp all come from oxidative phosphorylation . based on a lot of experimental work , it appears that four h $ ^+ $ ions must flow back into the matrix through atp synthase to power the synthesis of one atp molecule . when electrons from nadh move through the transport chain , about 10 h $ ^+ $ ions are pumped from the matrix to the intermembrane space , so each nadh yields about 2.5 atp . electrons from fadh $ _2 $ , which enter the chain at a later stage , drive pumping of only 6 h $ ^+ $ , leading to production of about 1.5 atp . with this information , we can do a little inventory for the breakdown of one molecule of glucose : stage|direct products ( net ) |ultimate atp yield ( net ) -|-|- glycolysis|2 atp|2 atp |2 nadh|3-5 atp pyruvate oxidation| 2 nadh|5 atp citric acid cycle|2 atp/gtp|2 atp |6 nadh|15 atp |2 fadh $ _2 $ |3 atp total| |30-32 atp one number in this table is still not precise : the atp yield from nadh made in glycolysis . this is because glycolysis happens in the cytosol , and nadh ca n't cross the inner mitochondrial membrane to deliver its electrons to complex i . instead , it must hand its electrons off to a molecular “ shuttle system ” that delivers them , through a series of steps , to the electron transport chain . some cells of your body have a shuttle system that delivers electrons to the transport chain via fadh $ _2 $ . in this case , only 3 atp are produced for the two nadh of glycolysis . other cells of your body have a shuttle system that delivers the electrons via nadh , resulting in the production of 5 atp . in bacteria , both glycolysis and the citric acid cycle happen in the cytosol , so no shuttle is needed and 5 atp are produced . 30-32 atp from the breakdown of one glucose molecule is a high-end estimate , and the real yield may be lower . for instance , some intermediates from cellular respiration may be siphoned off by the cell and used in other biosynthetic pathways , reducing the number of atp produced . cellular respiration is a nexus for many different metabolic pathways in the cell , forming a network that ’ s larger than the glucose breakdown pathways alone . self-check questions
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so , where does oxygen fit into this picture ? oxygen sits at the end of the electron transport chain , where it accepts electrons and picks up protons to form water . if oxygen isn ’ t there to accept electrons ( for instance , because a person is not breathing in enough oxygen ) , the electron transport chain will stop running , and atp will no longer be produced by chemiosmosis .
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if there is no adp at the time in the mitochondrial matrix , will o2 still be utilised to accept electrons at the end of the electron transport chain ?
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