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33 Cards in this Set
- Front
- Back
Acetyl CoEnzyme A |
Under aerobic conditions, pyruvate enters the mitochondria where it is converted into acetyl CoA Acetyl CoA is the fuel for the citric Acid Cycle (CAC), which processes the 2 carbon acetly unit to 2 molecules of CO2 while generating high-energy electrons that can be used to form ATP |
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How do sugars and lipids connect? |
acetyl CoA |
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Pyruvate Dehydrogenase Complex |
a mitochondrial matrix enzyme, oxidatively decarboxylates pyruvate to form acetyl CoA 3 enzymes make up the complex |
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What does the Pyruvate Dehydrogenase Complex catalyze |
1 decarboxylates pyruvate 2 oxidation 3 attachment of coenzyme A Pyruvate to Acetyl CoA involves the production of high energy molecules-->2 e |
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Fates of Acetyl CoA |
Metabolism by CAC Incorporation into fatty acids |
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Two regulatory mechanisms of Pyruvate to Acetyl CoA (Pyruvate dehydrogenase complex) |
Enzyme E1 a kinase associated with the complex phosphorylates and inactivates E1 A phosphatase, also in the complex, removes the phosphate and thereby activates the enzyme Energy Charge ATP, Acetyl CoA, NADH inhibit the complex ADP and pyruvate stimulate the complex |
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The two stages of the CAC |
decarboxylation and regeneration of oxaloacetate |
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Cellular respiration involves |
two pathways 1. CAC 2. Oxidative phosphorylation both in the mitochondria |
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CoASH |
reduced acetyl attaches to H after oxidation |
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Substrates of CAC in order |
Citrate Isocitrate α ketoglutarate Succinyl CoA Succinate Fumarate Malate Oxaloacetate Citrate |
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Enzymes of CAC in order |
Citrate *Aconitase Isocitrate *Isocitrate dehydrogenase α ketoglutarate *αKetoglutarate dehydrogenase complex Succinyl CoA *Succinyl CoA synthetase Succinate *Succinate dehydrogenase Fumarate *Fumarase Malate *Malate dehydrogenase Oxaloacetate *Citrate synthase Citrate |
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Rxns of CAC stage one |
1. Introduction of two carbons as acetyl-CoA-formingcitrate 2. Citrate isomerization 3. Isocitrate is oxidized to form NADH and CO2 4. a-Ketoglutarate is oxidized; forms NADH and CO2 Reactions 3 and 4 are oxidative decarboxylationreactions |
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Rxns of CAC stage two |
5. Cleavage of Succinyl-CoA leads to substrate-levelphosphorylation 6. Succinate is oxidized to form fumarate and FADH2 7. Fumarate is hydrated and forms L-malate 8. Malate is oxidized to form oxaloacetate and a thirdNADH |
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The key catabolic function of CAC |
is the production of high energy electrons in the form of NADH and FADH2 |
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Electrons from NADH and FADH2 |
each NADH has 2 e forms 2.5 ATP when used to reduce oxygen in e transport chain FADH2 forms 1.5 ATP with the reduction of oxygen in the e transport chain |
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how many oxidation reactions are in the CAC |
5--> 4 dehydrogenases and one fumarase of 5 two are oxidative decarboxylation |
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what is special about step 1,2,8 |
1 condensation 2 dehydration 8 coupled with one with concentration to overcome positive change in G |
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CAC regulated by |
Isocitrate dehydrogenase + ADP - ATPand NADH α ketogluterate dehydrogenase - ATP, succinyl CoA, and NADH |
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Biosynthesis through oxaloacetate |
glucose aspartate-->other aas, purines, pyrimidines |
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Biosynthesis through Succinyl CoA |
Porphyrins, heme, chlorophyll |
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Biosynthesis through α ketogluterate |
Glutamate-->other aas-->purines |
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Biosynthesis through Citrate |
fatty acids, sterols |
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Anapleuretic rxn |
replenishing rxn. replenish intermediates that occur within a cycle. Pyruvate to oxaloacetate catalyzed by pyruvate carboxylase |
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Citrate * Isocitrate |
Citrate *Aconitase Isocitrate |
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Isocitrate * α ketoglutarate |
Isocitrate dehydrogenase |
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α Ketoglutarate * Succinyl CoA |
α Ketoglutarate deydrohenase complex |
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Succinyl CoA * Succinate |
Succinyl CoA sythetase |
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Succinate * Fumarate |
Succinate Dehydrogenase |
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Fumarate * Malate |
Fumarase |
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Malate * Oxaloacetate |
Malate dehydrogenase |
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Oxaloacetate * Citrate |
Citrate Synthase |
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