text stringlengths 4 7.07k | text_hash stringlengths 32 32 | __index_level_0__ int64 1 1.81M |
|---|---|---|
Charles and Henry Capehart , in the American Civil War , the latter for saving a drowning man while under fire .
| dcb4fce27e538ff51eec807210cbb5c4 | 38,776 |
Antoine and Julien Gaujot . The Gaujots also have the unique distinction of receiving their medals for actions in separate conflicts , Antoine in the Philippine – American War and Julien when he crossed the border to rescue Mexicans and Americans in a Mexican Revolution skirmish .
| 6847ce47179bf0f5babd2aba7877830e | 38,777 |
Harry and Willard Miller , during the same naval action in the Spanish – American War .
| 73c6540563c8a1377551916ddea6bf6f | 38,778 |
Allen and James Thompson , in the same American Civil War action .
| 92012f9f31f61ea05a387cbef3a06b9d | 38,779 |
Another notable pair of related recipients are Admiral Frank Friday Fletcher ( rear admiral at the time of award ) and his nephew , Admiral Frank Jack Fletcher ( lieutenant at the time of award ) , both awarded for actions during the United States occupation of Veracruz .
| d9e77fcf6417aca0346e5b21710b007d | 38,780 |
= = = Belated recognition = = =
| 6844704987055dd3d59b230fac8b2cbf | 38,782 |
Since 1979 , 85 belated Medal of Honor decorations were presented to recognize actions from the Civil War to the Vietnam War . In addition , five recipients who names were not included on the Army Medal of Honor Roll in 1917 had their awards restored .
| 26d1a76d102a64505277ac1b28614323 | 38,784 |
A 1993 study commissioned by the U.S. Army investigated " racial disparity " in the awarding of medals . At the time , no Medals of Honor had been awarded to American soldiers of African descent who served in World War II . After an exhaustive review , the study recommended that ten Distinguished Service Cross recipie... | 497100ed1cfbe62c62a0810d8efe3cb8 | 38,785 |
In 1998 , a similar study of Asian Americans resulted in President Bill Clinton presenting 22 Medals of Honor in 2000 . Twenty of these medals went to American soldiers of Japanese descent of the 442nd Regimental Combat Team ( 442nd RCT ) that served in the European Theater of Operations during World War II . One of t... | e83fab44814276815ff4d2649e37bebe | 38,786 |
In 2005 , President George W. Bush presented the Medal of Honor to Tibor Rubin , a Hungarian @-@ born American Jew who was a Holocaust survivor of World War II and enlisted U.S. infantryman and prisoner of war in the Korean War , whom many believed to have been overlooked because of his religion .
| acdd4d78a11d3a5de6fb5355f637fa8a | 38,787 |
On April 11 , 2013 , President Obama presented the Medal of Honor posthumously to Army chaplain Captain Emil Kapaun for his actions as a prisoner of war during the Korean war . This follows other awards to Army Sergeant Leslie H. Sabo , Jr. for conspicuous gallantry in action on May 10 , 1970 , near Se San , Cambodia ... | 530477b1deab8b9a9976721a3da7e791 | 38,788 |
As a result of a Congressionally mandated review to ensure brave acts were not overlooked due to prejudice or discrimination , on March 18 , 2014 President Obama upgraded Distinguished Service Crosses to Medals of Honor for 24 Hispanic , Jewish , and African American individuals — the " Valor 24 " — for their actions ... | 69ff0333c019543b1e9f4fd925b29497 | 38,789 |
= = 27th Maine and other revoked awardings = =
| fe37e33e3835351021f493998c4fb367 | 38,791 |
During the Civil War , Secretary of War Edwin M. Stanton promised a Medal of Honor to every man in the 27th Maine Volunteer Infantry Regiment who extended his enlistment beyond the agreed @-@ upon date . The Battle of Gettysburg was imminent , and 311 men of the regiment volunteered to serve until the battle was resol... | c0eb40368835121d7deb605cb6d2ee2c | 38,793 |
In 1916 , a board of five Army generals on the retired list convened under act of law to review every Army Medal of Honor awarded . The board was to report on any Medals of Honor awarded or issued for any cause other than distinguished service . The commission , led by Nelson A. Miles , identified 911 awards for cause... | 521bd016d6a865bc841a62c2fc11b158 | 38,794 |
= = Nomination under current consideration = =
| 692c68ae2f22ff67513fc77287056a87 | 38,796 |
David Dunnels White 's nomination is under consideration for the capture of Confederate Major General G. W. Custis Lee , eldest son of General Robert E. Lee , at the Battle of Sailors Creek , Virginia , on April 6 , 1865 .
| 03746442b79695d3f58a6bd45d1797ac | 38,798 |
= = Similar American decorations = =
| 082634a782c4e9f078dadf439f9ec432 | 38,800 |
The following decorations , in one degree or another , bear similar names to the Medal of Honor , but are entirely separate awards with different criteria for issuance :
| c5f90b1d892b5cbdbe79606978cf5fe5 | 38,802 |
Cardenas Medal of Honor : decoration of the United States Revenue Cutter Service , which was later merged into the United States Coast Guard
| 2df5b2ce55405cc60a7442d1dc3fc629 | 38,803 |
Chaplain 's Medal for Heroism : awarded posthumously for a single action to four recipients
| d5ecdeff14acac0b08b4e2d5d4b4cb6c | 38,804 |
Congressional Gold Medal : the highest civilian honor bestowed by the United States ( along with the Presidential Medal of Freedom )
| 76a2d432af6954e5293fc7f7130970a1 | 38,805 |
Congressional Space Medal of Honor : intended for issuance to astronauts , but despite its name , it is not equal to the Medal of Honor
| 07d026344b94fc5cc4e84d87ae2d88d0 | 38,806 |
Presidential Medal of Freedom : the highest civilian honor bestowed by the United States ( along with the Congressional Gold Medal )
| 8034eee730cf4ddd20eb98ed9bc19bf7 | 38,807 |
Several United States law enforcement decorations bear the name " Medal of Honor " . The Public Safety Officer Medal of Valor , established by Congress in 2001 and stated to be " the highest National award for valor by a public safety officer " , is also awarded by the President of the United States .
| 237168c387a9d356454fefce8ea5fdca | 38,808 |
= Bacteria =
| c16bad20dcb463bb07060ee27613ed96 | 38,811 |
Bacteria ( / bækˈtɪəriə / ; singular : bacterium ) constitute a large domain of prokaryotic microorganisms . Typically a few micrometres in length , bacteria have a number of shapes , ranging from spheres to rods and spirals . Bacteria were among the first life forms to appear on Earth , and are present in most of its... | 12e290844c94e95940c1c74d719f0417 | 38,813 |
There are typically 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water . There are approximately 5 × 1030 bacteria on Earth , forming a biomass which exceeds that of all plants and animals . Bacteria are vital in recycling nutrients , with many of the stages in nu... | 28cfaf2cd0979d255cdd9d0aeb15a33b | 38,814 |
Most bacteria have not been characterized , and only about half of the bacterial phyla have species that can be grown in the laboratory . The study of bacteria is known as bacteriology , a branch of microbiology .
| e0740877ad84e679f00c4c5c013e6d25 | 38,815 |
There are approximately ten times as many bacterial cells in the human flora as there are human cells in the body , with the largest number of the human flora being in the gut flora , and a large number on the skin . The vast majority of the bacteria in the body are rendered harmless by the protective effects of the i... | 15e99fce29b215083930b96bd92b5d67 | 38,816 |
Once regarded as plants constituting the class Schizomycetes , bacteria are now classified as prokaryotes . Unlike cells of animals and other eukaryotes , bacterial cells do not contain a nucleus and rarely harbour membrane @-@ bound organelles . Although the term bacteria traditionally included all prokaryotes , the ... | 05c608bd0f85a662a62ebdef0fc06656 | 38,817 |
= = Etymology = =
| 7fea396da2a2c19c0da296faa651b7f5 | 38,819 |
The word bacteria is the plural of the New Latin bacterium , which is the latinisation of the Greek βακτήριον ( bakterion ) , the diminutive of βακτηρία ( bakteria ) , meaning " staff , cane " , because the first ones to be discovered were rod @-@ shaped .
| 1ccdbdf65ce8b8690d93c671ec930931 | 38,821 |
= = Origin and early evolution = =
| 579a2565cb03bc21010c680dd1cf85b4 | 38,823 |
The ancestors of modern bacteria were unicellular microorganisms that were the first forms of life to appear on Earth , about 4 billion years ago . For about 3 billion years , most organisms were microscopic , and bacteria and archaea were the dominant forms of life . In 2008 , fossils of macroorganisms were discovere... | 8734339af51fd6574e40b1889c0e0e23 | 38,825 |
= = Morphology = =
| b859137a2e99fcdccd0d16095fc3faba | 38,827 |
Bacteria display a wide diversity of shapes and sizes , called morphologies . Bacterial cells are about one @-@ tenth the size of eukaryotic cells and are typically 0 @.@ 5 – 5 @.@ 0 micrometres in length . However , a few species are visible to the unaided eye — for example , Thiomargarita namibiensis is up to half a... | 4a9031c6df4f7d94620470704bf825ae | 38,829 |
Most bacterial species are either spherical , called cocci ( sing. coccus , from Greek kókkos , grain , seed ) , or rod @-@ shaped , called bacilli ( sing. bacillus , from Latin baculus , stick ) . Elongation is associated with swimming . Some bacteria , called vibrio , are shaped like slightly curved rods or comma @-... | bf8c048d35b131fc499eef7d69b71b66 | 38,830 |
Many bacterial species exist simply as single cells , others associate in characteristic patterns : Neisseria form diploids ( pairs ) , Streptococcus form chains , and Staphylococcus group together in " bunch of grapes " clusters . Bacteria can also be elongated to form filaments , for example the Actinobacteria . Fil... | 7d1976c310e1928f6b6422a8c75d13a3 | 38,831 |
Bacteria often attach to surfaces and form dense aggregations called biofilms or bacterial mats . These films can range from a few micrometers in thickness to up to half a meter in depth , and may contain multiple species of bacteria , protists and archaea . Bacteria living in biofilms display a complex arrangement of... | 7a2f0137c3a1e51e299f2613a3011752 | 38,832 |
Even more complex morphological changes are sometimes possible . For example , when starved of amino acids , Myxobacteria detect surrounding cells in a process known as quorum sensing , migrate toward each other , and aggregate to form fruiting bodies up to 500 micrometres long and containing approximately 100 @,@ 000... | 5eecd253ecaa427c2d4a6acca91536b8 | 38,833 |
= = Cellular structure = =
| 59a9e83eb1e3900e67dba4124f4b8e80 | 38,835 |
= = = Intracellular structures = = =
| b565a011ead0db787a89e103a38a1461 | 38,838 |
The bacterial cell is surrounded by a cell membrane ( also known as a lipid , cytoplasmic or plasma membrane ) . This membrane encloses the contents of the cell and acts as a barrier to hold nutrients , proteins and other essential components of the cytoplasm within the cell . As they are prokaryotes , bacteria do not... | 8b9b35ed930809ce802ec2c30d002cc0 | 38,840 |
Bacterial microcompartments , such as carboxysomes , provide a further level of organization ; they are compartments within bacteria that are surrounded by polyhedral protein shells , rather than by lipid membranes . These " polyhedral organelles " localize and compartmentalize bacterial metabolism , a function perfor... | 5cc41ce0aa8c3f707f982c577309af2e | 38,841 |
Many important biochemical reactions , such as energy generation , use concentration gradients across membranes . The general lack of internal membranes in bacteria means reactions such as electron transport occur across the cell membrane between the cytoplasm and the periplasmic space . However , in many photosynthet... | a01de6df6945156029ac6c9d1795b596 | 38,842 |
Bacteria do not have a membrane @-@ bound nucleus , and their genetic material is typically a single circular DNA chromosome located in the cytoplasm in an irregularly shaped body called the nucleoid . The nucleoid contains the chromosome with its associated proteins and RNA . The phylum Planctomycetes and candidate p... | dceedfe1215992906695622611f43e33 | 38,843 |
Some bacteria produce intracellular nutrient storage granules for later use , such as glycogen , polyphosphate , sulfur or polyhydroxyalkanoates . Certain bacterial species , such as the photosynthetic Cyanobacteria , produce internal gas vesicles , which they use to regulate their buoyancy – allowing them to move up ... | c222b338ac3c6b014477d35cfd743063 | 38,844 |
= = = Extracellular structures = = =
| 089d124dbf0104eca2b658660e1b6bad | 38,846 |
In most bacteria , a cell wall is present on the outside of the cell membrane . The cell membrane and cell wall comprise the cell envelope . A common bacterial cell wall material is peptidoglycan ( called " murein " in older sources ) , which is made from polysaccharide chains cross @-@ linked by peptides containing D... | 9cfb2381eb3d0854d974eee7cf8e0fd1 | 38,848 |
There are broadly speaking two different types of cell wall in bacteria , a thick one in the gram @-@ positives and a thinner one in the gram @-@ negatives . The names originate from the reaction of cells to the Gram stain , a test long @-@ employed for the classification of bacterial species .
| 6a03de583f054fc818c6e62398933a31 | 38,849 |
Gram @-@ positive bacteria possess a thick cell wall containing many layers of peptidoglycan and teichoic acids . In contrast , gram @-@ negative bacteria have a relatively thin cell wall consisting of a few layers of peptidoglycan surrounded by a second lipid membrane containing lipopolysaccharides and lipoproteins .... | ae897f93dadad21099395daa944c802a | 38,850 |
Acid @-@ fast bacteria , such as Mycobacteria , are resistant to decolorization by acids during staining procedures . The high mycolic acid content of Mycobacteria , is responsible for the staining pattern of poor absorption followed by high retention . The most common staining technique used to identify acid @-@ fast... | 480b9a3d84bd80cd411fda454d56bd8c | 38,851 |
In many bacteria , an S @-@ layer of rigidly arrayed protein molecules covers the outside of the cell . This layer provides chemical and physical protection for the cell surface and can act as a macromolecular diffusion barrier . S @-@ layers have diverse but mostly poorly understood functions , but are known to act a... | 1bbdc1a9157a2ecf8f1e59f5759540ff | 38,852 |
Flagella are rigid protein structures , about 20 nanometres in diameter and up to 20 micrometres in length , that are used for motility . Flagella are driven by the energy released by the transfer of ions down an electrochemical gradient across the cell membrane .
| 8ff32bbc575f17451c08c66cfda4578d | 38,853 |
Fimbriae ( sometimes called " attachment pili " ) are fine filaments of protein , usually 2 – 10 nanometres in diameter and up to several micrometers in length . They are distributed over the surface of the cell , and resemble fine hairs when seen under the electron microscope . Fimbriae are believed to be involved in... | b621d1be711263c6e36033fdd52f2586 | 38,854 |
Glycocalyx are produced by many bacteria to surround their cells , and vary in structural complexity : ranging from a disorganised slime layer of extra @-@ cellular polymer to a highly structured capsule . These structures can protect cells from engulfment by eukaryotic cells such as macrophages ( part of the human im... | 1e6857cfffa229318a5fd6c6bbee8b36 | 38,855 |
The assembly of these extracellular structures is dependent on bacterial secretion systems . These transfer proteins from the cytoplasm into the periplasm or into the environment around the cell . Many types of secretion systems are known and these structures are often essential for the virulence of pathogens , so are... | 2e5f706592c33ab03c6770d434c21f88 | 38,856 |
= = = Endospores = = =
| b8d44057d59a7d42b5d1934fdf58249b | 38,858 |
Certain genera of gram @-@ positive bacteria , such as Bacillus , Clostridium , Sporohalobacter , Anaerobacter , and Heliobacterium , can form highly resistant , dormant structures called endospores . In almost all cases , one endospore is formed and this is not a reproductive process , although Anaerobacter can make ... | 9b82c91bf1434642198e4ef253eb93c7 | 38,860 |
Endospores show no detectable metabolism and can survive extreme physical and chemical stresses , such as high levels of UV light , gamma radiation , detergents , disinfectants , heat , freezing , pressure , and desiccation . In this dormant state , these organisms may remain viable for millions of years , and endospo... | 74b2545ddd8f22c0b02cea8dd86f83d1 | 38,861 |
= = Metabolism = =
| f82a6244c42c86a2bc4891c34395d39f | 38,863 |
Bacteria exhibit an extremely wide variety of metabolic types . The distribution of metabolic traits within a group of bacteria has traditionally been used to define their taxonomy , but these traits often do not correspond with modern genetic classifications . Bacterial metabolism is classified into nutritional group... | 348d4e01ddd93e1f9c91cf4a259dab7f | 38,865 |
Carbon metabolism in bacteria is either heterotrophic , where organic carbon compounds are used as carbon sources , or autotrophic , meaning that cellular carbon is obtained by fixing carbon dioxide . Heterotrophic bacteria include parasitic types . Typical autotrophic bacteria are phototrophic cyanobacteria , green s... | d1bafb805c35901dd41cad2aaa28670f | 38,866 |
Bacteria are further divided into lithotrophs that use inorganic electron donors and organotrophs that use organic compounds as electron donors . Chemotrophic organisms use the respective electron donors for energy conservation ( by aerobic / anaerobic respiration or fermentation ) and biosynthetic reactions ( e.g. , ... | 40b6a54c76d6c50a3fc553c692eb0ce9 | 38,867 |
Another way of life of chemotrophs in the absence of possible electron acceptors is fermentation , wherein the electrons taken from the reduced substrates are transferred to oxidised intermediates to generate reduced fermentation products ( e.g. , lactate , ethanol , hydrogen , butyric acid ) . Fermentation is possibl... | 76dfb1c6457b47c05071cd2dc95c1eb7 | 38,868 |
These processes are also important in biological responses to pollution ; for example , sulfate @-@ reducing bacteria are largely responsible for the production of the highly toxic forms of mercury ( methyl- and dimethylmercury ) in the environment . Non @-@ respiratory anaerobes use fermentation to generate energy an... | de4a608aece773a06c7000adc8b77307 | 38,869 |
Lithotrophic bacteria can use inorganic compounds as a source of energy . Common inorganic electron donors are hydrogen , carbon monoxide , ammonia ( leading to nitrification ) , ferrous iron and other reduced metal ions , and several reduced sulfur compounds . In unusual circumstances , the gas methane can be used by... | 93b2bb2e9fdc07ead7d46cfd79e20507 | 38,870 |
In addition to fixing carbon dioxide in photosynthesis , some bacteria also fix nitrogen gas ( nitrogen fixation ) using the enzyme nitrogenase . This environmentally important trait can be found in bacteria of nearly all the metabolic types listed above , but is not universal .
| ea747b4ca786f4e6dc54bf83c880340b | 38,871 |
Regardless of the type of metabolic process they employ , the majority of bacteria are able to take in raw materials only in the form of relatively small molecules , which enter the cell by diffusion or through molecular channels in cell membranes . The Planctomycetes are the exception ( as they are in possessing memb... | 74ee5f6fb2bd93abf340135c4cbd462b | 38,872 |
= = Growth and reproduction = =
| e1b67cd28bf8536f8353bce758619233 | 38,874 |
Unlike in multicellular organisms , increases in cell size ( cell growth ) and reproduction by cell division are tightly linked in unicellular organisms . Bacteria grow to a fixed size and then reproduce through binary fission , a form of asexual reproduction . Under optimal conditions , bacteria can grow and divide e... | 4cd63bb404130642106d908e6742dfc1 | 38,876 |
In the laboratory , bacteria are usually grown using solid or liquid media . Solid growth media , such as agar plates , are used to isolate pure cultures of a bacterial strain . However , liquid growth media are used when measurement of growth or large volumes of cells are required . Growth in stirred liquid media occ... | bc83afbac2a34afa8c0764e4835a14bb | 38,877 |
Most laboratory techniques for growing bacteria use high levels of nutrients to produce large amounts of cells cheaply and quickly . However , in natural environments , nutrients are limited , meaning that bacteria cannot continue to reproduce indefinitely . This nutrient limitation has led the evolution of different ... | 5c4d769b8364d46663a13be81d260b94 | 38,878 |
Bacterial growth follows four phases . When a population of bacteria first enter a high @-@ nutrient environment that allows growth , the cells need to adapt to their new environment . The first phase of growth is the lag phase , a period of slow growth when the cells are adapting to the high @-@ nutrient environment ... | 5dc77cb8267b7c6e64d77f6804f53962 | 38,879 |
= = Genetics = =
| 21b5b3ca57287fef932cde54a3156d7e | 38,881 |
Most bacteria have a single circular chromosome that can range in size from only 160 @,@ 000 base pairs in the endosymbiotic bacteria Candidatus Carsonella ruddii , to 12 @,@ 200 @,@ 000 base pairs in the soil @-@ dwelling bacteria Sorangium cellulosum . Spirochaetes of the genus Borrelia are a notable exception to th... | ffb67d8926c66063b8d0f280a90af458 | 38,883 |
Bacteria may also contain plasmids , which are small extra @-@ chromosomal DNAs that may contain genes for antibiotic resistance or virulence factors . Plasmids replicate independently of chromosomes , so it is possible that plasmids could be lost in bacterial cell division . Against this possibility is the fact that ... | de90c6258ff502c3834af0ecabfa177d | 38,884 |
Bacteria , as asexual organisms , inherit identical copies of their parent 's genes ( i.e. , they are clonal ) . However , all bacteria can evolve by selection on changes to their genetic material DNA caused by genetic recombination or mutations . Mutations come from errors made during the replication of DNA or from e... | 26d20e77d756e6cfe683f965280be1e6 | 38,885 |
= = = DNA transfer = = =
| 8b34ec6a10d7b1f32060342eff1dcf2d | 38,887 |
Some bacteria also transfer genetic material between cells . This can occur in three main ways . First , bacteria can take up exogenous DNA from their environment , in a process called transformation . Genes can also be transferred by the process of transduction , when the integration of a bacteriophage introduces for... | 830c65c41774f413d854981e52d02560 | 38,889 |
Transduction of bacterial genes by bacteriophage appears to be a consequence of infrequent errors during intracellular assembly of virus particles , rather than a bacterial adaptation . Conjugation , in the much @-@ studied E. coli system is determined by plasmid genes , and is an adaptation for transferring copies of... | b3777a99b18f63e65f7700acfd722909 | 38,890 |
Transformation , unlike transduction or conjugation , depends on numerous bacterial gene products that specifically interact to perform this complex process , and thus transformation is clearly a bacterial adaptation for DNA transfer . In order for a bacterium to bind , take up and recombine donor DNA into its own chr... | 9c4f24d960a59d7c08f0895705b27a9d | 38,891 |
In ordinary circumstances , transduction , conjugation , and transformation involve transfer of DNA between individual bacteria of the same species , but occasionally transfer may occur between individuals of different bacterial species and this may have significant consequences , such as the transfer of antibiotic re... | 22c201593eca0af0796cd4ace5cae87f | 38,892 |
= = = Bacteriophages = = =
| 964c0dfe9946844c6a771fc58ba08a98 | 38,894 |
Bacteriophages are viruses that infect bacteria . Many types of bacteriophage exist , some simply infect and lyse their host bacteria , while others insert into the bacterial chromosome . A bacteriophage can contain genes that contribute to its host 's phenotype : for example , in the evolution of Escherichia coli O15... | 5b35ab9d690b58db7899903bd6889cd7 | 38,896 |
= = Behavior = =
| d02d8f86b374348faf69cedc7ce04de2 | 38,898 |
= = = Secretion = = =
| 8f9d050f49dbf979a850740b44f5a162 | 38,901 |
Bacteria frequently secrete chemicals into their environment in order to modify it favorably . The secretions are often proteins and may act as enzymes that digest some form of food in the environment .
| 68408ce59c72ac51d2373ceb17413980 | 38,903 |
= = = Bioluminescence = = =
| 82840a04287fcd392d2ebf97c9324ee0 | 38,905 |
A few bacteria have chemical systems that generate light . This bioluminescence often occurs in bacteria that live in association with fish , and the light probably serves to attract fish or other large animals .
| 08a1181fbea54c4dc47c96c71761d947 | 38,907 |
= = = Multicellularity = = =
| 82a9bb7427f4ae10ea60ffef8887e176 | 38,909 |
Bacteria often function as multicellular aggregates known as biofilms , exchanging a variety of molecular signals for inter @-@ cell communication , and engaging in coordinated multicellular behavior .
| 55dcfc26c80b4f8bdce64961697151d6 | 38,911 |
The communal benefits of multicellular cooperation include a cellular division of labor , accessing resources that cannot effectively be utilized by single cells , collectively defending against antagonists , and optimizing population survival by differentiating into distinct cell types . For example , bacteria in bio... | 0d1e1c9194ddf54359c9c54e37b0d25b | 38,912 |
One type of inter @-@ cellular communication by a molecular signal is called quorum sensing , which serves the purpose of determining whether there is a local population density that is sufficiently high that it is productive to invest in processes that are only successful if large numbers of similar organisms behave ... | 1754c987a0d2e51f141897b3f4a84078 | 38,913 |
Quorum sensing allows bacteria to coordinate gene expression , and enables them to produce , release and detect autoinducers or pheromones which accumulate with the growth in cell population .
| 63d4b0be018da870bc5df2c75216d227 | 38,914 |
= = = Movement = = =
| 372c239e43b89e059b3029c26035c0d3 | 38,916 |
Many bacteria can move using a variety of mechanisms : flagella are used for swimming through fluids ; bacterial gliding and twitching motility move bacteria across surfaces ; and changes of buoyancy allow vertical motion .
| ffb8b3dda78981499e9ea7ff435df49a | 38,918 |
Swimming bacteria frequently move near 10 body lengths per second and a few as fast as 100 . This makes them at least as fast as fish , on a relative scale .
| 971b1de689b8dafdce8cc63276691b49 | 38,919 |
In bacterial gliding and twitching motility , bacteria use their type IV pili as a grappling hook , repeatedly extending it , anchoring it and then retracting it with remarkable force ( > 80 pN ) .
| f249309ee7817556353c9dc02ee86724 | 38,920 |
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