alleryStart learning →During the oxidation of the hydroxyethyl group to an acetyl group, where do the removed electrons go?
AThey are picked up by NAD plus
BThey are picked up by coenzyme A
CThey are picked up by oxaloacetate
DThey are picked up by oxygen gas
Answer & Solution
Correct answer: A. They are picked up by NAD plus
1. Step two of the conversion oxidizes the two-carbon hydroxyethyl group into an acetyl group.
2. Oxidation means electrons are stripped away and must land somewhere.
3. They are picked up by the oxidized carrier NAD plus, forming NADH.
4. The high-energy electrons carried by that NADH are used later to generate adenosine triphosphate.
5. Coenzyme A joins in step three and carries the acetyl group itself rather than the electrons.
_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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