alleryStart learning →In step five of the citric acid cycle, what replaces coenzyme A on the succinyl group?
AA phosphate group
BAn amino group
CA carboxyl group
DA hydroxyl group
Answer & Solution
Correct answer: A. A phosphate group
1. Step five works on the succinyl group carried by coenzyme A.
2. A phosphate group is substituted for coenzyme A and a high-energy bond is formed.
3. That bond energy drives substrate-level phosphorylation as the succinyl group becomes succinate.
4. The product is either guanine triphosphate or adenosine triphosphate, depending on the tissue.
_Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 7 "Cellular Respiration", section 7.3 Oxidation of Pyruvate and the Citric Acid Cycle_
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