PHYSIOLOGY
MUSCLE ENERGETICS TCA CYCLE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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citrate ____
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isocitrate ____
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malate ____
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Detailed explanation-1: -For each acetyl group that enters the citric acid cycle, three molecules of NADH are produced.
Detailed explanation-2: -Lactic acid is never a part of citric acid cycle. Acetyl Co A, citric acid and succinic acid are part of citric acid cycle. Lactic acid is produced in anaerobic respiration in muscles. Thus, the correct answer is option D.
Detailed explanation-3: -First, acetyl CoA combines with oxaloacetate, a four-carbon molecule, losing the CoA group and forming the six-carbon molecule citrate. After citrate undergoes a rearrangement step, it undergoes an oxidation reaction, transferring electrons to NAD+ to form NADH and releasing a molecule of carbon dioxide.
Detailed explanation-4: -Explanation: The only enzyme listed in the answer choices that does not catalyze a reaction within the citric acid cycle is pyruvate kinase. Pyruvate kinase is an important enzyme in the final step of glycolysis, as it catalyzes the conversion of phosphoenolpyruvate and ADP to pyruvate and ATP.