How many oxidation reactions occur in the citric acid cycle?

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Multiple Choice

How many oxidation reactions occur in the citric acid cycle?

Four oxidation steps occur in each turn of the citric acid cycle. As the cycle progresses, four dehydrogenase reactions remove electrons: isocitrate is oxidized to α-ketoglutarate (NADH formed); α-ketoglutarate is oxidized to succinyl-CoA (NADH formed); succinate is oxidized to fumarate (FADH2 formed); and malate is oxidized to oxaloacetate (NADH formed). The other steps involve rearrangement or substrate-level phosphorylation, not oxidation. So, per acetyl-CoA entering the cycle, there are four oxidation reactions.

Four oxidation steps occur in each turn of the citric acid cycle. As the cycle progresses, four dehydrogenase reactions remove electrons: isocitrate is oxidized to α-ketoglutarate (NADH formed); α-ketoglutarate is oxidized to succinyl-CoA (NADH formed); succinate is oxidized to fumarate (FADH2 formed); and malate is oxidized to oxaloacetate (NADH formed). The other steps involve rearrangement or substrate-level phosphorylation, not oxidation. So, per acetyl-CoA entering the cycle, there are four oxidation reactions.

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