Kreb Cycle Flashcards
What is the link between glycolysis and TCA?
Pyruvate Dehydrogenase (PDH)
Alterane Fates of Pyruvate
(4)
- Alanine (transamination)
- Oxaloacetate (Carboxylation)
- Aceytl CoA (Oxidative Decarboxylation)
- Lactate (Reduction)
PDH and TCA Cycle occur in what part of the cell?
Matrix of Mitochondria
What transports pyruvate to the mitochondrial matrix?
Pyruvate translocase
PDH reaction is very complex and?
Irreversible
PDH Complex requires 3 enzymes
- Pyruvate dehydrogenase-E1
- Dihydrolipoyl transacetylase-E2
- Dihydrolipoyl dehydrogenase-E3
Two regulatory proteins in PDH
- Protein Kinase
- Protein Phosphatase
PDH Complex requires 5 coenzymes
1.TPP-B1
2. FAD-from B2
3. NAD+-B3
4.Lipoid Acid
5. CoASH-derived from B5
PDH enzymes & their co enzymes
- Pyruvate dehydrogenase-E1-TPP
- Dihydrolipoyl transacetylase-E2-Lipioc acid & CoA
- Dihydrolipoyl dehydrogenase-E3-FAD & NAD+
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Pyruvate Dehydrogenase Deficiency results in what?
Severe reduction of ATP production
TCA (Krebs Cycle)
Starts with Acetyl-CoA
- Citrate
- Isocitrate
- Alpha ketoglutarate
- Succinyl CoA
- Succinate
- Fumarate
- Malate
- Oxaloacetate
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What is the overall yield of TCA?
1 TCA cycle revolution produces
3 NADH (1:3)
1 FADH2 (1:2)
1 GTP (1:1)
TOTAL: 12 ATP
What substrates are oxidized to form FADH2 and NADH?
In the Krebs cycle
Isocitrate-NADH
Alpha Ketoglutarate-NADH
Succinate-FADH2
Malate-NADH
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What are the Four Regulated Enzymes in the TCA Cycle
- Citrate Synthase (NADH)
- Isocitrate Dehydrogenase (NADH)
- alpha-ketoglutarate (NADH)
- Succinate Dehydrogenase (FADH2)
Regulation of Citrate Synthase
- Activated primarily by substrate availability
- Inhibited by ATP, NADH, Acetyl CoA
- Activated by calcium and ADP
Function of the electron transport chain and oxidative phosphorylation
- Create a proton gradient across inner mitochondrial membrane
- Proton gradient then drives phosphorylation of ADP to ATP
- Generate electrical energy by passing electrons to oxygen
What are the five complexes of the Electron Transport Chain
Complex 1: NADH dehydrogenase complex
Complex 2: Succinate dehydrogenase complex
Complex 3: Cytochrome b and c1
Complex 4: Cytochrome oxidase complex-transported electrons, molecular oxygen and free protons are brought together to produce H20
Complex 5: ATP synthase complex-accepts or donates electrons to mobile carriers like CoQ and Cyt C