Biochemistry 3 Views 1 Answers
Which product of the electron transport chain reenters the Krebs cycle? A. ATP B. CoA C. NAD⁺ D. NADH E. Pyruvate
Which product of the electron transport chain reenters the Krebs cycle?
- A. ATP
- B. CoA
- C. NAD⁺
- D. NADH
- E. Pyruvate
Answered
The correct answer is:
C. NAD⁺
Explanation:
During the electron transport chain, NADH is oxidized, donating electrons to the chain and becoming NAD+^+. This NAD+^+ is then available to re-enter the Krebs cycle (citric acid cycle), where it can pick up electrons again during the oxidation of substrates (such as acetyl-CoA), forming NADH once more.
Why the other options are incorrect:
- A. ATP: ATP is produced in the electron transport chain but is not directly recycled in the Krebs cycle.
- B. CoA: Coenzyme A (CoA) is involved in the formation of acetyl-CoA, which enters the Krebs cycle, but it does not re-enter the Krebs cycle after the electron transport chain.
- D. NADH: NADH is produced in the Krebs cycle, and it donates electrons to the electron transport chain, but it does not re-enter the Krebs cycle.
- E. Pyruvate: Pyruvate is converted to acetyl-CoA before entering the Krebs cycle, but it does not re-enter the cycle after the electron transport chain.
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