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23 Cards in this Set
- Front
- Back
Fermentation |
- ATP-producing catabolic pathway in which both electron donors and acceptors are organic compounds - can be anaerobic catabolism of organic nutrients - results in partial degradation of sugars - yields 18x less ATP than fermentation |
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Cellular respiration |
- ATP-producing catabolic process where inorganic molecule (e.g. oxygen) accepts electron - Organic compounds (food) + Oxygen -> Carbon dioxide + Water + Energy - carbs, proteins, and fats can all be metabolized, but most often described as glucose: C6H12O6 + 6O2 -> 6CO2 + 6H2O + energy (ATP + heat) |
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Redox reactions |
- involves partial or complete transfer of electrons
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Oxidation |
- GE R OA - in cellular respiration: C6H12O6 -> 6CO2 - not oxidzed in one explosive step, but enzymes gradualy lower activation energy so oxidation can happen in a stepwise fashion |
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Reduction |
- LE O RA - in cellular respiration: 6O2 + 6H2O |
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Reducing agent |
- substance that is oxidized |
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Oxidizing agent |
- substance that is reduced - NAD+ functions as oxidizing agent: NAD+ to NADH - NAD+ reaction catalyzed by dehydrogenases, which: (1) remove 2E2P from substrate (2) deliver 2E1P to NAD+ (3) release remaining H+ in surrounding solution
substrate + NAD+ -dehydrogenase-> oxidized substrate + NADH + H_ |
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NAD+ |
- electron acceptor to which hydrogens stripped from glucose are passed - Nicotinamide adenine dinucleotide: dinucleotide that functions as a coenzyme in redox reactions of metabolism |
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Glycolysis |
- in cytosol - glucose (6C) into two pyruvate (3C) - 2 ATP invested, 4 ATP 2NADH produced (1) Energy-investment i. C6 of glucose phosphorylated by hexokinase (1 ATP) -> glucose-6-phosphate ii. isomerase rearranges G6P -> fructose-6-phosphate iii. C1 of F6P phosphorylated by phosphofructokinase (1 ATP) -> fructose-1,6-diphosphate iv. F16D cleaved by aldolase -> dihydroxyacetone phosphate and glyceraldehyde phosphate v. dihydroxyacetone phosphate pulled towards glyceraldehyde phosphate by isomerase
(2) Energy-yielding via. Glyceraldehyde phosphate oxidized by triose phosphate dehydrogenase -> 1,3-diphosphoglycerate; NAD+ reduced -> NADH + H+ vib: C1 of 1,3-dipg phosphorylated with inorganic phosphate in cytosol vii. High-energy bond in 1,3-dipg transferred to ADP -> 2ATP!!~~ and 3-phosphoglycerate viii. C3 phosphate group on 3-phosphoglycerate transferred to C2 -> 2-phosphoglycerate ix. water molecule removed, creating double bond between C1 and C2 -> phosphoenolpyruvate x. PEP phosphorylated, transferred to ADP -> 2 ATP!!UIOFU)(# + pyruvate
- can also hydrolyze: starch -> glucose, proteins -> amino acids (excess converted to intermediates) -> fats oxidized to ATP |
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Krebs cycle |
- in mitochondrial matrix - acetyl CoA (pyruvate derivative) -> carbon dioxide - pyruvate to acetyl CoA: 2 NADH - produces 2 ATP (6), 6 NADH (4, 5, 9), 2 FADH2 (7) - 2 rounds required to oxidize glucose (1) Pyruvate oxidized -> acetyl CoA i. CO2 from carboxyl group of pyruvate removed, releasing CO2 ii. 2C-fragment oxidized to acetate, and NAD+ reduced to NADH iii. CoA attached to acetyl group (2) 2C acetyl bonds to 4C acetylate -> 6C citrate (when conc. up, Gly step 3 slows, keeps rates in sync) (3) Citrate isomerized -> isocitrate (4) Isocitrate loses CO2 -> 5C a-ketogluterate; NAD+ reduced -> NADH (5) CO2 removed from a-keto, CoA attached -> 4C Succinyl CoA; NAD+ reduced -> NADH (6) CoA displaced by a phosphate group, transferred to GDP -> GTP and succinate; GTP transfers phosphate group to ADP -> ATP !!#!# (7) Succinate oxidized -> fumarate; FAD reduced -> FADH2 (8) Fumarate + water -> malate (9) Malate oxidized -> oxoacetate; NAD+ reduced -> NADH |
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Oxidative phosphorylation |
- ATP synthesis - NADH and FADH2 pass electrons down electron transport chain to oxygen -> every successive carrier has higher EN - NADH -> H2O + 2-3 ATPs per electron pair from NADH - FADH contributes e- at lower energy level -> worth 2 ATPs max - resulting protein gradient stores potential energy which can be sed to phosphorylate ATP (1) NADH oxidized, flavoprotein reduced -> e- transferred from NADH to flavin mononucleotide (FMN) (2) FMN oxidized -> passes electrons to iron-sulfur protein (3) Iron-sulfur proteins oxidized -> passes electrons to ubiquinone (Q) (4) Q oxidized -> passes electrons to cytochromes (5) Cyta3, last cytochrome, passes electrons to O2 (6) O2 reduced to H2O |
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Substrate-level phosphorylation |
- ATP production by direct enzymatic transfer of phosphate from an intermediate substrate to ADP |
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Acetyl CoA |
- acetyl coenzyme A |
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Cytochrome (cyt) |
- type of protein molecule that contains a heme prosthetic group and functions as electron carrier - prosthetic groups: accept and donate electrons - heme prosthetic group: 4 organic rings surrounding single iron atom -> iron transfers electrons |
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ATP synthase |
- enzyme that makes ATP using proton gradient - allows H+ to diffuse back across the membrane, which causes phosphorylation of ADP |
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Chemiosmosis |
- coupling between chemical reactions (phosphorylation) and transport processes (proton transport) - pumps H+ across membrane from mitochondrial matrix -> inner membrane -> intermembrane space - phospholipid bilayer is imp[ermeable to H+ so no backflow - surface area for chemiosmosis increasd by cristae |
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Protein-motive force |
- pH in intermembrane space is lower than in matrix, but sae as cytosol because outer mitochondrial membrane is permeable to proons - potential energy stored in proton gradient: two components (1) chemical gradient: concentration gradient of protons (2): electrical gradient: voltagee across membrane - drives cellular work! |
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Aerobic |
- existing in the presence of oxygen - pyrvate oxidized further by substrate-level phosphorylation and oxidative phosphorylation |
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Anaerobic |
- existing in the absence of free oxygen - pyruvate reduced, no dditional ATP produced |
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Alcohol fermentation |
- pyruvate -> ethanol (1) pyruvate loses CO2 -> converted to 2C acetaldehyde (2) NADH oxidized -> NAD+; acetaldehyde redudced -> ethanol - bacteria and yeast |
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Lactic acid fermentation |
(1) pyruvate reduced -> lactate (2) NADH oxidized -> NAD+ - cheese and yogurt - muscle cells switch to lactic acid fermentation when O2 scarce -> lactate accumulates -> carried to liver -> converted back to pyruvate |
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Facultative anaerobe |
- capable of growth in either aerobic or anaerobic environments - e.g. yeasts, bacteria, mammalian muscle cells |
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Beta oxidation |
- converts energy in fats to acetyl CoA - resulting 2C fragments can enter Krebs cycle |