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18 terms

Biology 7

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autotroph
An organism able to build all the complex organic molecules that it requires as its own food source, using only simple inorganic compounds.
heterotroph
An organism that cannot derive energy from photosynthesis or inorganic chemicals, and so must feed on other plants and animals, obtaining chemical energy by degrading their organic molecules.
cellular respiration
The metabolic harvesting of energy by oxidation, ultimately dependent on molecular oxygen; carried out by the Krebs cycle and oxidative phosphorylation.
digestion
The breakdown of complex, usually insoluble foods into molecules that can be absorbed into cells, where they are degraded to yield energy and the raw materials for synthetic processes.
dehydrogenation
Chemical reaction involving the loss of a hydrogen atom. This is an oxidation that combines loss of an electron with loss of a proton.
nicotine adenine dinucleotide (NAD+)
A molecule that becomes reduced (to NADH) as it carries high-energy electrons from oxidized molecules and delivers them to ATP-producing pathways in the cell.
aerobic respiration
The process that results in the complete oxidation of glucose using oxygen as the final electron acceptor. Oxygen acts as the final electron acceptor for and electron transport chain that produces a proton gradient for the chemiosmotic synthesis of ATP.
anaerobic respiration
The use of electron transport to generate a proton gradient for chemiosmotic synthesis of ATP using a final electron acceptor other than oxygen.
fermentation
The enzyme-catalyzed extraction of energy from organic compounds without the involvement of oxygen.
electron transport chain
The passage of energetic electrons through a series of membrane-associated electron-carrier molecules to proton pumps embedded within mitochondrial or chloroplast membranes.
pyruvate
A three-carbon molecule that is the end product of glycolysis; each glucose molecule yields two pyruvate molecules.
acetyl-CoA
The product of the transition reaction between glycolysis and the Krebs cycle. Pyruvate is oxidized to acetyl-CoA by NAD+, also producing CO2, and NADH.
Krebs cycle
Another name for the citric acid cycle; also called the tricarboxylic acid (TCA) cycle.
chemiosmosis
The mechanism by which ATP is generated in mitochondria and chloroplasts; energetic electrons excited by light (in chloroplasts) or extracted by oxidation in the Krebs cycle (in mitochondria) are used to drive proton pumps, creating a proton concentration gradient; when protons subsequently flow back across the membrane, they pass through channels that couple their movement to the synthesis of ATP.
glyceraldehyde 3-phosphate (G3P)
The three-carbon molecule that is the product of the reaction that splits a 6-carbon diphosphate during glycolysis. G3P is also an intermediate in the Calvin cycle during photosynthesis.
flavin adenine dinucleotide (FAD)
A cofactor that acts as a soluble (not membrane bound) electron carrier (can be reversibly oxidized and reduced).
NADH dehydrogenase
An enzyme located on the inner mitochondrial membrane that catalyzes the oxidation by NAD+ of pyruvate to Acetyl-CoA. This reaction links glycolysis and the Krebs cycle.
deamination
The removal of an amino group; part of the degradation of proteins into compounds that can enter the Krebs cycle.