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If NADH cannot be metabolized through aerobic respiration, another electron acceptor is used. Most organisms will use some form of fermentation to accomplish the regeneration of NAD+, ensuring the continuation of glycolysis. The regeneration of NAD+in fermentation is not accompanied by ATP production; therefore, the po... | https://openstax.org/books/concepts-biology/pages/4-chapter-summary |
The breakdown and synthesis of carbohydrates, proteins, and lipids connect with the pathways of glucose catabolism. The carbohydrates that can also feed into glucose catabolism include galactose, fructose, and glycogen. These connect with glycolysis. The amino acids from proteins connect with glucose catabolism through... | https://openstax.org/books/concepts-biology/pages/4-chapter-summary |
acetyl CoA : the combination of an acetyl group derived from pyruvic acid and coenzyme A which is made from pantothenic acid (a B-group vitamin) | https://openstax.org/books/concepts-biology/pages/4-key-terms |
activation energy : the amount of initial energy necessary for reactions to occur | https://openstax.org/books/concepts-biology/pages/4-key-terms |
active site : a specific region on the enzyme where the substrate binds | https://openstax.org/books/concepts-biology/pages/4-key-terms |
allosteric inhibition : the mechanism for inhibiting enzyme action in which a regulatory molecule binds to a second site (not the active site) and initiates a conformation change in the active site, preventing binding with the substrate | https://openstax.org/books/concepts-biology/pages/4-key-terms |
anabolic : describes the pathway that requires a net energy input to synthesize complex molecules from simpler ones | https://openstax.org/books/concepts-biology/pages/4-key-terms |
anaerobic cellular respiration : the use of an electron acceptor other than oxygen to complete metabolism using electron transport-based chemiosmosis | https://openstax.org/books/concepts-biology/pages/4-key-terms |
ATP : (also, adenosine triphosphate) the cellâs energy currency | https://openstax.org/books/concepts-biology/pages/4-key-terms |
ATP synthase : a membrane-embedded protein complex that regenerates ATP from ADP with energy from protons diffusing through it | https://openstax.org/books/concepts-biology/pages/4-key-terms |
bioenergetics : the concept of energy flow through living systems | https://openstax.org/books/concepts-biology/pages/4-key-terms |
catabolic : describes the pathway in which complex molecules are broken down into simpler ones, yielding energy as an additional product of the reaction | https://openstax.org/books/concepts-biology/pages/4-key-terms |
chemiosmosis : the movement of hydrogen ions down their electrochemical gradient across a membrane through ATP synthase to generate ATP | https://openstax.org/books/concepts-biology/pages/4-key-terms |
citric acid cycle : a series of enzyme-catalyzed chemical reactions of central importance in all living cells that harvests the energy in carbon-carbon bonds of sugar molecules to generate ATP; the citric acid cycle is an aerobic metabolic pathway because it requires oxygen in later reactions to proceed | https://openstax.org/books/concepts-biology/pages/4-key-terms |
competitive inhibition : a general mechanism of enzyme activity regulation in which a molecule other than the enzymeâs substrate is able to bind the active site and prevent the substrate itself from binding, thus inhibiting the overall rate of reaction for the enzyme | https://openstax.org/books/concepts-biology/pages/4-key-terms |
electron transport chain : a series of four large, multi-protein complexes embedded in the inner mitochondrial membrane that accepts electrons from donor compounds and harvests energy from a series of chemical reactions to generate a hydrogen ion gradient across the membrane | https://openstax.org/books/concepts-biology/pages/4-key-terms |
endergonic : describes a chemical reaction that results in products that store more chemical potential energy than the reactants | https://openstax.org/books/concepts-biology/pages/4-key-terms |
enzyme : a molecule that catalyzes a biochemical reaction | https://openstax.org/books/concepts-biology/pages/4-key-terms |
exergonic : describes a chemical reaction that results in products with less chemical potential energy than the reactants, plus the release of free energy | https://openstax.org/books/concepts-biology/pages/4-key-terms |
feedback inhibition : a mechanism of enzyme activity regulation in which the product of a reaction or the final product of a series of sequential reactions inhibits an enzyme for an earlier step in the reaction series | https://openstax.org/books/concepts-biology/pages/4-key-terms |
fermentation : the steps that follow the partial oxidation of glucose via glycolysis to regenerate NAD+; occurs in the absence of oxygen and uses an organic compound as the final electron acceptor | https://openstax.org/books/concepts-biology/pages/4-key-terms |
glycolysis : the process of breaking glucose into two three-carbon molecules with the production of ATP and NADH | https://openstax.org/books/concepts-biology/pages/4-key-terms |
heat energy : the energy transferred from one system to another that is not work | https://openstax.org/books/concepts-biology/pages/4-key-terms |
in vitro : taking place in a test tube, culture dish, or elsewhere outside a living organism | https://openstax.org/books/concepts-biology/pages/4-key-terms |
kinetic energy : the type of energy associated with objects in motion | https://openstax.org/books/concepts-biology/pages/4-key-terms |
metabolism : all the chemical reactions that take place inside cells, including those that use energy and those that release energy | https://openstax.org/books/concepts-biology/pages/4-key-terms |
noncompetitive inhibition : a general mechanism of enzyme activity regulation in which a regulatory molecule binds to a site other than the active site and prevents the active site from binding the substrate; thus, the inhibitor molecule does not compete with the substrate for the active site; allosteric inhibition is ... | https://openstax.org/books/concepts-biology/pages/4-key-terms |
oxidative phosphorylation : the production of ATP by the transfer of electrons down the electron transport chain to create a proton gradient that is used by ATP synthase to add phosphate groups to ADP molecules | https://openstax.org/books/concepts-biology/pages/4-key-terms |
potential energy : the type of energy that refers to the potential to do work | https://openstax.org/books/concepts-biology/pages/4-key-terms |
substrate : a molecule on which the enzyme acts | https://openstax.org/books/concepts-biology/pages/4-key-terms |
thermodynamics : the science of the relationships between heat, energy, and work | https://openstax.org/books/concepts-biology/pages/4-key-terms |
The process of photosynthesis transformed life on earth. By harnessing energy from the sun, photosynthesis allowed living things to access enormous amounts of energy. Because of photosynthesis, living things gained access to sufficient energy, allowing them to evolve new structures and achieve the biodiversity that is ... | https://openstax.org/books/concepts-biology/pages/5-chapter-summary |
Only certain organisms, called autotrophs, can perform photosynthesis; they require the presence of chlorophyll, a specialized pigment that can absorb light and convert light energy into chemical energy. Photosynthesis uses carbon dioxide and water to assemble carbohydrate molecules (usually glucose) and releases oxyge... | https://openstax.org/books/concepts-biology/pages/5-chapter-summary |
In the first part of photosynthesis, the light-dependent reaction, pigment molecules absorb energy from sunlight. The most common and abundant pigment is chlorophylla. A photon strikes photosystem II to initiate photosynthesis. Energy travels through the electron transport chain, which pumps hydrogen ions into the thyl... | https://openstax.org/books/concepts-biology/pages/5-chapter-summary |
Using the energy carriers formed in the first stage of photosynthesis, the Calvin cycle reactions fix CO2from the environment to build carbohydrate molecules. An enzyme, RuBisCO, catalyzes the fixation reaction, by combining CO2with RuBP. The resulting six-carbon compound is broken down into two three-carbon compounds,... | https://openstax.org/books/concepts-biology/pages/5-chapter-summary |
absorption spectrum : the specific pattern of absorption for a substance that absorbs electromagnetic radiation | https://openstax.org/books/concepts-biology/pages/5-key-terms |
autotroph : an organism capable of producing its own food | https://openstax.org/books/concepts-biology/pages/5-key-terms |
Calvin cycle : the reactions of photosynthesis that use the energy stored by the light-dependent reactions to form glucose and other carbohydrate molecules | https://openstax.org/books/concepts-biology/pages/5-key-terms |
carbon fixation : the process of converting inorganic CO2gas into organic compounds | https://openstax.org/books/concepts-biology/pages/5-key-terms |
chlorophyll : the green pigment that captures the light energy that drives the reactions of photosynthesis | https://openstax.org/books/concepts-biology/pages/5-key-terms |
chlorophylla : the form of chlorophyll that absorbs violet-blue and red light | https://openstax.org/books/concepts-biology/pages/5-key-terms |
chlorophyllb : the form of chlorophyll that absorbs blue and red-orange light | https://openstax.org/books/concepts-biology/pages/5-key-terms |
chloroplast : the organelle where photosynthesis takes place | https://openstax.org/books/concepts-biology/pages/5-key-terms |
electromagnetic spectrum : the range of all possible frequencies of radiation | https://openstax.org/books/concepts-biology/pages/5-key-terms |
granum : a stack of thylakoids located inside a chloroplast | https://openstax.org/books/concepts-biology/pages/5-key-terms |
heterotroph : an organism that consumes other organisms for food | https://openstax.org/books/concepts-biology/pages/5-key-terms |
light-dependent reaction : the first stage of photosynthesis where visible light is absorbed to form two energy-carrying molecules (ATP and NADPH) | https://openstax.org/books/concepts-biology/pages/5-key-terms |
mesophyll : the middle layer of cells in a leaf | https://openstax.org/books/concepts-biology/pages/5-key-terms |
photoautotroph : an organism capable of synthesizing its own food molecules (storing energy), using the energy of light | https://openstax.org/books/concepts-biology/pages/5-key-terms |
photon : a distinct quantity or âpacketâ of light energy | https://openstax.org/books/concepts-biology/pages/5-key-terms |
photosystem : a group of proteins, chlorophyll, and other pigments that are used in the light-dependent reactions of photosynthesis to absorb light energy and convert it into chemical energy | https://openstax.org/books/concepts-biology/pages/5-key-terms |
pigment : a molecule that is capable of absorbing light energy | https://openstax.org/books/concepts-biology/pages/5-key-terms |
stoma : the opening that regulates gas exchange and water regulation between leaves and the environment; plural: stomata | https://openstax.org/books/concepts-biology/pages/5-key-terms |
stroma : the fluid-filled space surrounding the grana inside a chloroplast where the Calvin cycle reactions of photosynthesis take place | https://openstax.org/books/concepts-biology/pages/5-key-terms |
thylakoid : a disc-shaped membranous structure inside a chloroplast where the light-dependent reactions of photosynthesis take place using chlorophyll embedded in the membranes | https://openstax.org/books/concepts-biology/pages/5-key-terms |
wavelength : the distance between consecutive points of a wave | https://openstax.org/books/concepts-biology/pages/5-key-terms |
Prokaryotes have a single loop chromosome, whereas eukaryotes have multiple, linear chromosomes surrounded by a nuclear membrane. Human somatic cells have 46 chromosomes consisting of two sets of 22 homologous chromosomes and a pair of nonhomologous sex chromosomes. This is the 2n,or diploid, state. Human gametes have ... | https://openstax.org/books/concepts-biology/pages/6-chapter-summary |
The cell cycle is an orderly sequence of events. Cells on the path to cell division proceed through a series of precisely timed and carefully regulated stages. In eukaryotes, the cell cycle consists of a long preparatory period, called interphase. Interphase is divided into G1, S, and G2phases. Mitosis consists of five... | https://openstax.org/books/concepts-biology/pages/6-chapter-summary |
Each step of the cell cycle is monitored by internal controls called checkpoints. There are three major checkpoints in the cell cycle: one near the end of G1, a second at the G2âM transition, and the third during metaphase. | https://openstax.org/books/concepts-biology/pages/6-chapter-summary |
Cancer is the result of unchecked cell division caused by a breakdown of the mechanisms regulating the cell cycle. The loss of control begins with a change in the DNA sequence of a gene that codes for one of the regulatory molecules. Faulty instructions lead to a protein that does not function as it should. Any disrupt... | https://openstax.org/books/concepts-biology/pages/6-chapter-summary |
In both prokaryotic and eukaryotic cell division, the genomic DNA is replicated and each copy is allocated into a daughter cell. The cytoplasmic contents are also divided evenly to the new cells. However, there are many differences between prokaryotic and eukaryotic cell division. Bacteria have a single, circular DNA c... | https://openstax.org/books/concepts-biology/pages/6-chapter-summary |
anaphase : the stage of mitosis during which sister chromatids are separated from each other | https://openstax.org/books/concepts-biology/pages/6-key-terms |
binary fission : the process of prokaryotic cell division | https://openstax.org/books/concepts-biology/pages/6-key-terms |
cell cycle : the ordered sequence of events that a cell passes through between one cell division and the next | https://openstax.org/books/concepts-biology/pages/6-key-terms |
cell cycle checkpoints : mechanisms that monitor the preparedness of a eukaryotic cell to advance through the various cell cycle stages | https://openstax.org/books/concepts-biology/pages/6-key-terms |
cell plate : a structure formed during plant-cell cytokinesis by Golgi vesicles fusing at the metaphase plate; will ultimately lead to formation of a cell wall to separate the two daughter cells | https://openstax.org/books/concepts-biology/pages/6-key-terms |
centriole : a paired rod-like structure constructed of microtubules at the center of each animal cell centrosome | https://openstax.org/books/concepts-biology/pages/6-key-terms |
cleavage furrow : a constriction formed by the actin ring during animal-cell cytokinesis that leads to cytoplasmic division | https://openstax.org/books/concepts-biology/pages/6-key-terms |
cytokinesis : the division of the cytoplasm following mitosis to form two daughter cells | https://openstax.org/books/concepts-biology/pages/6-key-terms |
diploid : describes a cell, nucleus, or organism containing two sets of chromosomes (2n) | https://openstax.org/books/concepts-biology/pages/6-key-terms |
FtsZ : a tubulin-like protein component of the prokaryotic cytoskeleton that is important in prokaryotic cytokinesis (name origin:Filamentingtemperature-sensitive mutantZ) | https://openstax.org/books/concepts-biology/pages/6-key-terms |
G0phase : a cell-cycle phase distinct from the G1phase of interphase; a cell in G0is not preparing to divide | https://openstax.org/books/concepts-biology/pages/6-key-terms |
G1phase : (also, first gap) a cell-cycle phase; first phase of interphase centered on cell growth during mitosis | https://openstax.org/books/concepts-biology/pages/6-key-terms |
G2phase : (also, second gap) a cell-cycle phase; third phase of interphase where the cell undergoes the final preparations for mitosis | https://openstax.org/books/concepts-biology/pages/6-key-terms |
gamete : a haploid reproductive cell or sex cell (sperm or egg) | https://openstax.org/books/concepts-biology/pages/6-key-terms |
gene : the physical and functional unit of heredity; a sequence of DNA that codes for a specific peptide or RNA molecule | https://openstax.org/books/concepts-biology/pages/6-key-terms |
genome : the entire genetic complement (DNA) of an organism | https://openstax.org/books/concepts-biology/pages/6-key-terms |
haploid : describes a cell, nucleus, or organism containing one set of chromosomes (n) | https://openstax.org/books/concepts-biology/pages/6-key-terms |
homologous chromosomes : chromosomes of the same length with genes in the same location; diploid organisms have pairs of homologous chromosomes, and the members of each pair come from different parents | https://openstax.org/books/concepts-biology/pages/6-key-terms |
interphase : the period of the cell cycle leading up to mitosis; includes G1, S, and G2phases; the interim between two consecutive cell divisions | https://openstax.org/books/concepts-biology/pages/6-key-terms |
kinetochore : a protein structure in the centromere of each sister chromatid that attracts and binds spindle microtubules during prometaphase | https://openstax.org/books/concepts-biology/pages/6-key-terms |
locus : the position of a gene on a chromosome | https://openstax.org/books/concepts-biology/pages/6-key-terms |
metaphase : the stage of mitosis during which chromosomes are lined up at the metaphase plate | https://openstax.org/books/concepts-biology/pages/6-key-terms |
metaphase plate : the equatorial plane midway between two poles of a cell where the chromosomes align during metaphase | https://openstax.org/books/concepts-biology/pages/6-key-terms |
mitosis : the period of the cell cycle at which the duplicated chromosomes are separated into identical nuclei; includes prophase, prometaphase, metaphase, anaphase, and telophase | https://openstax.org/books/concepts-biology/pages/6-key-terms |
mitotic phase : the period of the cell cycle when duplicated chromosomes are distributed into two nuclei and the cytoplasmic contents are divided; includes mitosis and cytokinesis | https://openstax.org/books/concepts-biology/pages/6-key-terms |
mitotic spindle : the microtubule apparatus that orchestrates the movement of chromosomes during mitosis | https://openstax.org/books/concepts-biology/pages/6-key-terms |
oncogene : a mutated version of a proto-oncogene, which allows for uncontrolled progression of the cell cycle, or uncontrolled cell reproduction | https://openstax.org/books/concepts-biology/pages/6-key-terms |
origin : the region of the prokaryotic chromosome at which replication begins | https://openstax.org/books/concepts-biology/pages/6-key-terms |
prometaphase : the stage of mitosis during which mitotic spindle fibers attach to kinetochores | https://openstax.org/books/concepts-biology/pages/6-key-terms |
prophase : the stage of mitosis during which chromosomes condense and the mitotic spindle begins to form | https://openstax.org/books/concepts-biology/pages/6-key-terms |
proto-oncogene : a normal gene that controls cell division by regulating the cell cycle that becomes an oncogene if it is mutated | https://openstax.org/books/concepts-biology/pages/6-key-terms |
quiescent : describes a cell that is performing normal cell functions and has not initiated preparations for cell division | https://openstax.org/books/concepts-biology/pages/6-key-terms |
S phase : the second, or synthesis phase, of interphase during which DNA replication occurs | https://openstax.org/books/concepts-biology/pages/6-key-terms |
septum : a wall formed between bacterial daughter cells as a precursor to cell separation | https://openstax.org/books/concepts-biology/pages/6-key-terms |
telophase : the stage of mitosis during which chromosomes arrive at opposite poles, decondense, and are surrounded by new nuclear envelopes | https://openstax.org/books/concepts-biology/pages/6-key-terms |
tumor suppressor gene : a gene that codes for regulator proteins that prevent the cell from undergoing uncontrolled division | https://openstax.org/books/concepts-biology/pages/6-key-terms |
Nearly all eukaryotes undergo sexual reproduction. The variation introduced into the reproductive cells by meiosis appears to be one of the advantages of sexual reproduction that has made it so successful. Meiosis and fertilization alternate in sexual life cycles. The process of meiosis produces genetically unique repr... | https://openstax.org/books/concepts-biology/pages/7-chapter-summary |
Sexual reproduction requires that diploid organisms produce haploid cells that can fuse during fertilization to form diploid offspring. The process that results in haploid cells is called meiosis. Meiosis is a series of events that arrange and separate chromosomes into daughter cells. During the interphase of meiosis, ... | https://openstax.org/books/concepts-biology/pages/7-chapter-summary |
Meiosis and mitosis share similarities, but have distinct outcomes. Mitotic divisions are single nuclear divisions that produce daughter nuclei that are genetically identical and have the same number of chromosome sets as the original cell. Meiotic divisions are two nuclear divisions that produce four daughter nuclei t... | https://openstax.org/books/concepts-biology/pages/7-chapter-summary |
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