Which are outputs of the citric acid cycle?

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Multiple Choice

Which are outputs of the citric acid cycle?

In the citric acid cycle the main outputs are CO2, NADH, FADH2, and GTP. Each turn of the cycle oxidizes one acetyl-CoA, releasing two carbon dioxide molecules. Energy is captured in NADH and FADH2—three NADH and one FADH2 per turn—carrying high-energy electrons to the electron transport chain. A molecule of GTP (which can be converted to ATP) is produced by substrate-level phosphorylation inside the cycle. Oxygen isn’t produced by this cycle; it’s used later in the electron transport chain, and water is formed there as electrons are finally transferred to O2. Glucose is a starting substrate that feeds glycolysis, not an output of the cycle, and lactate is produced under anaerobic conditions, not by the citric acid cycle.

In the citric acid cycle the main outputs are CO2, NADH, FADH2, and GTP. Each turn of the cycle oxidizes one acetyl-CoA, releasing two carbon dioxide molecules. Energy is captured in NADH and FADH2—three NADH and one FADH2 per turn—carrying high-energy electrons to the electron transport chain. A molecule of GTP (which can be converted to ATP) is produced by substrate-level phosphorylation inside the cycle. Oxygen isn’t produced by this cycle; it’s used later in the electron transport chain, and water is formed there as electrons are finally transferred to O2. Glucose is a starting substrate that feeds glycolysis, not an output of the cycle, and lactate is produced under anaerobic conditions, not by the citric acid cycle.

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