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31 Cards in this Set
- Front
- Back
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1. What is the function of the TCA cycle?
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1. Oxidize acetyl group of acetyl CoA to CO2
2. Conserve the energy from oxidation as NADH and FADH2 |
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2. What is the net reaction of the TCA cycle?
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Reactants: acetyl CoA, 3 NAD+, FAD, 2H2O, GDP & Pi
Products: 2 CO2, CoASH, 3 NADH, FADH2, GTP, & 3H+ |
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3. What is the TCA cycle the final step of?
Where does the TCA cycle occur? Where are the enzymes of the TCA cycle found? |
Oxidation of glucose, lipids, and proteins
Mitochondria In matrix of mitochondria EXCEPT succinyl dehydrogenase |
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4. What is the relationship of the TCA cycle to the electron transport chain?
Where does the oxygen in oxaloacetate come from? |
Produces 4 pairs of electrons
Water |
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5. What is the order of reactions in the TCA cycle and the number of carbons in each intermediate?
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1. Acetyl CoA + oxaloacetate
2. Citrate (6 C) 3. Isocitrate (6 C) 4. α-ketoglutarate (5 C) 5. Succinyl CoA (4 C) 6. Succinate (4 C) 7. Fumarate (4 C0 8. Malarate (4 C) 9. Oxaloacetate (4 C) |
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6. How does the oxidation of acetyl CoA to CO2 occur?
What do the other reactions accomplish? |
4 oxidation-reduction reactions
Rearrange e- to facilitate transfer |
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7. What is the fuel for the TCA cycle and why?
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Acetyl Unit
Other intermediates are regenerated in each turn of the cycle |
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8. What happens in the first step of the TCA cycle?
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Acetyl CoA + Oxaloacetate -> Citrate
*Water comes in *CoASH is biproduct **Citrate synthase is enzyme |
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9. What happens in the second step of the TCA cycle?
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Citrate -> Isocitrate
*Both tricarboxylic acids *Both have 6 carbons |
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10. What type of reaction is the third step?
Describe it. |
Oxidation and Decarboxylation
Isocitrate -> α-ketoglutarate Enzyme: isocitrate dehydrogenase **NAD+ is reduced to NADH + H+ **Produce molecule of CO2 |
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11. What is isocitrate oxidized to?
What is this decarboxylated to? How many carbons are in the intermediates? |
Oxalosuccinate
α-ketoglutarate 6 C to 5 C |
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12. What type of reaction is the next reaction?
Describe it. |
Oxidation and Decarboxylation
α-ketoglutarate -> succinyl CoA Enzyme: α-ketoglutarate dehydrogenase |
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13. Where is the energy from the oxidation stored?
What are biproducts of this oxidation-decarboxylation reaction? |
Conserved in formation of thioester bond bwt succinyl and CoA
NADH + H+ CO2 |
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14. What is special about the enzyme α-ketoglutarate dehydrogenase?
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Multi-enzyme complex
It has 4 vitamins and 5 coenzymes **similar to pyruvate dehydrogenase |
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15. What are the five coenzymes?
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1. TTP (thiamine pyrophosphate)
2. Lipoamide 3. CoASH 4. FAD 5. NAD+ |
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16. What are the four vitamins?
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1. Riboflavin (FAD)
2. Niacin (NAD+) 3. Thiamine (TTP) 4. Pantothenate (CoA) |
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17. What step in the TCA cycle produces a high energy molecule?
What is this molecule? |
Succinyl CoA -> Succinate
GTP **Energy comes from thioester bond |
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18. What is the next oxidation reaction?
What is produced from this reaction? |
Succinate -> Fumarate
FADH2 **Form a double bond (FAD is involved in double bond formation and reduction of SH group) |
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19. What is the hydration reaction in the TCA cycle?
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Fumarate -> Malarate
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20. What is the final oxidation reaction?
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Malarate -> Oxaloacetate
NADH + H+ Enzyme: malate dehydrogenase |
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21. What type of conversion is NAD+ involved in?
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Conversion of alcohols to ketone
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22. Where are FAD and NAD+ located when accepting electrons?
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FAD accepts and donates electrons w/o being released from enzyme
NAD+ binds to enzyme and is released as NADH |
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23. What are the 4 oxidation reaction?
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1. Isocitrate -> α-ketoglutarate
2. α-ketoglutarate -> Succinyl CoA 3. Succinate -> Fumarate 4. Malate -> Oxaloacetate |
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24. What is being oxidized in each reaction and what is the enzyme involved?
Which reaction has FAD has the e- accpetor? |
1. Alcohol to ketone
isocitrate dehydrogenase 2. Oxidize carboxylic acid α-ketoglutarate dehydrogenase 3. Form double carbon bond succinate dehydrogenase 3. Oxidize alcohol malate dehydrogenase Succinate to Fumarate |
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25. What are the two decarboxylation reactions?
What do they produce? How do the number of carbons in the intermediates change? |
Isocitrate -> α-ketoglutarate
(6 -> 5) α-ketoglutarate -> succinyl CoA (5 -> 4) Produce CO2 |
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26. From what vitamin is CoA synthesized from?
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Pantothenate
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27. What are the two major routes for supplying oxaloacetate that are anaplerotic reactions?
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Anaploerotic: not part of TCA cycle but replenishes TCA cycle intermediate
1. Pyruvate carboxylase reaction (in liver and nerve tissue) *carboxylases contain biotin 2. Degradation of amino acids |
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28. Can the TCA cycle be anabolic?
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Yes, intermediates can be pulled away and be intermediates for other things
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29. What is another name for thiamine deficiency?
What is it most often associated with in Western society What are some symptoms of thiamine deficiency? |
Beri-beri
Alcoholism 1. Peripheral neuropathy 2. Pain in calves 3. Mental confusion 4. Weakness, amnesia, fatigue, atrophy of muscles |
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30. In humans how can niacin be synthesized to a limited extent?
What affects conversion of riboflavin to coenzyme form FAD? |
From dietary tryptophan
Thyroid status |
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31. Deficiencies in which two vitamins is rare?
Why? |
Pantothenate
-wide distribution in food and no specific syndrome in humans associated with deficiency Biotin -required in small amounts and synthesized by intestinal bacteria **can get biotin deficiency from consuming raw eggs |
