[Campbell Biology P.221] What is the total yield of high-energy molecules NADH, FADH2, and A... | Practice Question

Explanation

The text explicitly states: 'For each acetyl group entering the cycle, 3 NAD+ are reduced to NADH steps 3, 4, and 8 . In step 6, electrons are transferred not to NAD+, but to FAD, which accepts 2 electrons and 2 protons to become FADH2. In many animal tissue cells, the reaction in step 5 produces a guanosine triphosphate GTP molecule by substrate-level phosphorylation... The output from step 5 represents the only ATP generated during the citric acid cycle.' It then clarifies for glucose: 'Recall that each glucose gives rise to two molecules of acetyl CoA that enter the cycle. Because the numbers noted earlier are obtained from a single acetyl group entering the pathway, the total yield per glucose from the citric acid cycle turns out to be doubled, or 6 NADH, 2 FADH2, and the equivalent of 2 ATP.'