Term
| four steps of cellular respiration |
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Definition
• glucose is broken down to a pyruvate
• pyruvate is processed to form acetyl CoA
• acetyl CoA is oxidized to CO2
• compounds that were reduced in steps 1-3 are oxidized in reactions that lead to the production of ATP |
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Term
| reaction for oxidation of glucose |
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Definition
• C6H12O6 + 6O2 → 6CO2 + 6H2O
• glucose has high potential energy and donates electrons
• CO2 is the fully oxidized form of glucose
• glucose is reduced compared to CO2
• oxygen is the electron acceptor
• water is the product of the reduction of oxygen |
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Term
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Definition
• first step in oxidation of glucose
• occurs in cytoplasm (cytosol)
• input: glucose, NAD+, ADP
• total yield per glucose molecule: 2 NADH, 2 pyruvate, 2 ATP (net)
• substrate-level phosphorylation generates the ATP |
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Term
| Acetyl CoA formation/pyruvate processing |
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Definition
o occurs in mitochondrial matrix
o input: 2 pyruvate, CoA, NAD+
o output: CO2, 1 acetyl CoA per pyruvate, NADH
o conversion of pyruvate to acetyl CoA occurs in series of steps inside a huge, intricate enzyme complex called pyruvate dehydrogenase (in mitochondrial matrix) |
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Term
| where Krebs cycle/citric acid cycle takes place in prokaryotes and eukaryotes |
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Definition
| prokaryotes - cytoplasm; eukaryotes - mitochondrial matrix |
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Term
| Krebs cycle/citric acid cycle |
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Definition
o two runs of the citric acid cycle because 2 pyruvates made for every glucose, so 2 acetyl CoA
o input: NAD+, acetyl CoA, ADP
o total yield per pyruvate: 3 CO2, 4 NADH, 1 FADH2, 1 ATP (substrate-level phosphorylation)
o for each glucose oxidized to 6CO2, get 10 NADH, 2 FADH2, 4 ATP
o energy released by oxidation of one molecule of acetyl CoA powers the production of three NADH, one FADH2, and one GTP through substrate-level phosphorylation
• GTP converted to ATP
o each acetyl CoA is oxidized to two molecules of CO2
o some of the potential energy released from these reactions is used to
• reduce NAD+ to NADH
• reduce FAD to FADH2 |
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Term
| electron transport chain (ETC) |
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Definition
o uses electrons harvested from glucose to fuel ATP synthesis
o located in inner mitochondrial matrix and cristae of the mitochondrion
o accepts electrons from electrons carriers (NADH and FADH2) and pass them to oxygen (final electron acceptor)
o organized from least electronegative to most electronegative
• little bit of energy released at each step
o energy released from passing electrons down the ETC is used to pump protons up a concentration gradient from the matrix to the inner membrane space
• creates a proton gradient across the inner mitochondrial membrane
• proton-motive force: strong electrochemical gradient favoring the movement of protons back into the matrix
o ATP production depends solely on the existence of a proton-motive force |
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Term
| oxidative phosphorylation |
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Definition
• production of ATP molecules from the redox reactions of an ETC
o occurs in inner mitochondrial membrane
o ATP synthase uses the proton-motive force to make ATP
• ATP synthase located in the inner mitochondrial membrane
• when protons diffuse through ATP synthase, kinetic energy released causes knob to spin
• changes the conformation such that ADP is phosphorylated to form ATP
o electrons are finally passed on to oxygen (final electron acceptor), making water
o input: oxygen, NADH, ADP
o net output: NAD+, ATP, H2O |
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Term
| summary of cellular respiration |
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Definition
any process of ATP production that involves a compound that acts as an electron donor, an ETC, and an electron acceptor
o all carbons in glucose released as CO2
o harvest electrons are transferred from glucose to NADH and FADH2
o NADH and FADH2 transfer those electrons to ETC, where energy from their transfer fuels pumping of protons to create a proton-motive force
o ATP synthase allows protons to flow down their concentration gradient through a pore
o energy from proton diffusion fuels formation of ATP
o ETC donates electrons to oxygen, which picks up two protons and makes water
• takes place in mitochondria |
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Term
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Definition
making ATP without oxygen
o high levels of NADH inhibit enzyme complex the converts pyruvate to acetyl CoA
• pyruvate builds up and is made available as a substrate for enzymes of fermentation
• enzymes use NADH to reduce pyruvate, producing NAD+ that can be used for glycolysis
• reduction of pyruvate produces lactate or ethanol
• muscle cells have enzymes that convert pyruvate to lactic acid
• some bacteria and yeast have enzymes that convert pyruvate to ethanol |
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Term
| substrate-level phosphorylation |
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Definition
enzyme-catalyzed phosphorylation reactions that produce ATP during glycolysis and the Krebs cycle
• during this process, an enzyme catalyzes the transfer of a phosphate group from a phosphorylated substrate to ADP, resulting in ATP
• energy to make ATP comes from phosphorylated substrate, not a proton gradient (as in oxidative phosphorylation) |
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Term
| initial energy input, then energy payoff in glycolysis |
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Definition
o initial energy input needed to phosphorylate glucose
• ATP used to phosphorylate glucose into glucose-6-phosphate
• rearranged by an enzyme into fructose-6-phosphate
• ATP used again to add another phosphate, forming fructose 1,6-bisphosphate
o next, there is an energy payoff
• fructose 1,6-bisphosphate split into two 3-carbon compounds that are converted into 1,3-bisphosphate (meanwhile, 2 NAD+ reduced to make 2 NADH)
• ADP phosphorylated to form 2 ATP and 2 pyruvate |
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