Which statement about the energy yield from one turn of the TCA cycle (per acetyl-CoA) is correct?
- A It yields 1 GTP (equivalent to ATP), 3 NADH, and 1 FADH2 ✓
- B It yields 2 ATP, 2 NADH, and 2 FADH2 directly
- C It yields 3 ATP, 1 NADH, and 1 FADH2 directly
- D It yields 2 GTP, 2 NADH, and 2 FADH2
Correct answer: A. It yields 1 GTP (equivalent to ATP), 3 NADH, and 1 FADH2
Explanation
One turn of the TCA cycle yields 3 NADH, 1 FADH2, and 1 GTP (by substrate-level phosphorylation at succinyl-CoA synthetase). GTP is readily convertible to ATP by nucleoside diphosphate kinase. No ATP is generated directly in the cycle; the NADH and FADH2 feed the ETC. Distractor B is wrong because the cycle does not directly produce ATP and the numbers are incorrect.
Reference: Lehninger Principles of Biochemistry, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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