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Biochemistry

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TCA Cycle: Role of Oxygen

BIOCHM-DKFAE$

Glycolysis first evolved under anaerobic conditions and operates under anaerobic or aerobic conditions, whereas the TCA cycle operates only under aerobic conditions.

Which of the following statements accurately describes the role of oxygen in the TCA cycle?

A

Oxygen is directly involved in the pyruvate dehydrogenase complex multi-step catalysis in which pyruvate is converted to acetyl-CoA for entry into the TCA cycle.

B

Oxygen is required to regenerate ${ NADH }$ and ${ FADH }_{ 2 }$ produced by the TCA cycle.

C

Oxygen is a substrate for the succinyl-CoA synthetase reaction in which GTP is produced by substrate-level phosphorylation.

D

Oxygen is required as the initial electron donor to the mitochondrial electron transport system.