Term
| What are the roles of the TCA cycle? |
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Definition
1) Generate Energy by oxidizing acetyl-CoA to carbon dioxide and water
2) Supply biochemical intermediates for other pathways
3) Entry point of various degradative pathways for energy generation and gluconeogenesis |
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Term
| Carbohydrates will enter the TCA cycle as? |
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Definition
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Term
| Fatty acid oxidation will produce? |
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Definition
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Term
| Amino acid degradation leads to TCA cycle intermediates for? |
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Definition
1) Gluconeogenesis (a-ketoglutarate, succinyl-CoA, fumarate, oxaloacetate)
2) Energy generation |
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Term
| How does pyruvate enter the mitochondria? |
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Definition
1) Symport with H+ entering the matrix
2) Antiport with citrate leaving the matrix (citrate has -3 charge, while pyruvate has a -1 overall)
this separation shows off compartmentation |
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Term
What enzyme does this rxn...
Pyruvate + CoA + NAD+ --> Acetyl-CoA + CO2 + NADH + H+ |
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Definition
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Term
Pyruvate dehydrogenase is a very complex enzyme, and contains
5 subunits (2 regulatory, 3 catalytic). The catalytic subunits are? |
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Definition
1) Pyruvate decarboxylase (E1)
2) Transacetylase (E2)
3) Dihydrolipoyl dehydrogenase (E3) (shared with other enzymes) |
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Term
| What are the 5 cofactors of Pyruvate Dehydrogenase? |
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Definition
1) NAD+ (niacin)
2) FAD (riboflavin, B2)
3) Thiamine pyrophosphate (B1)
4) lipoic acid
5) coenzyme A |
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Term
| What two rxns in the TCA cycle have + delta G? |
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Definition
1) Aconitase rxn (citrate to isocitrate)
2) Malate Dehydrogenase (Malate to Oxaloacetate andNADH is formed) |
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Term
| What 3 enzymes produce NADH in the TCA cycle? |
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Definition
Isocitrate Dehydrogenase
alpha-ketoglutarate dehydrogenase
malate dehydrogenase |
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Term
| What enzyme produces FADH(2H) and where is it located? |
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Definition
| Succinate dehydrogenase, its located on the inner mitochondrial membrane |
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Term
| What enzyme produces GTP? |
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Definition
Succinate thiokinase
Succinyl-CoA is made into succinate also lose CoASH |
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Term
| What inhibits PDH (Pyruvate Dehydrogenase)? |
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Definition
| NADH and Acetyl-CoA (both are competitive inhibitors) |
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Term
| Citrate synthase is inhibited by? |
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Definition
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Term
| Isocitrate dehydrogenase is activated by? |
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Definition
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Term
| Isocitrate Dehydrogenase is inhibited by? |
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Definition
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Term
| Alpha-ketoglutarate dehydrogenase is inhibited by? |
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Definition
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Term
| Malate dehydrogenase is inhibited by? |
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Definition
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Term
| Why regulate isocitrate dehydrogenase? |
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Definition
1) To allow citrate to accumulate, which signifies adequate building blocks, and is a substrate for fat production
2) Citrate accumulates due to aconitase favoring citrate formation |
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Term
| Why regulate alpha-ketoglutarate dehydrogenase? |
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Definition
| alpha-ketoglutarate can form glutamate in one step, and leave the cycle. In times of excess energy, this is encouraged |
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