Multiple Choice
Which of the following correctly indicates the cellular location where pyruvate oxidation occurs?
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Review 3: Pyruvate & Fatty Acid Oxidation, Citric Acid Cycle, & Glycogen Metabolism
Pyruvate Oxidation
Multiple Choice
In the presence of oxygen, glycolysis is followed directly by which process that converts pyruvate into acetyl-CoA for entry into the citric acid cycle?
A
Conversion of pyruvate to lactate by lactate dehydrogenase (lactic acid fermentation)
B
Conversion of pyruvate to ethanol and by alcoholic fermentation
C
Carboxylation of pyruvate to oxaloacetate by pyruvate carboxylase as the primary fate of pyruvate under aerobic conditions
D
Pyruvate oxidation by the pyruvate dehydrogenase complex (oxidative decarboxylation of pyruvate to acetyl-CoA)
Verified step by step guidance1
Identify the fate of pyruvate under aerobic conditions (presence of oxygen). Glycolysis produces pyruvate, which then enters the mitochondria for further processing.
Recall that under aerobic conditions, pyruvate is converted into acetyl-CoA, which is the molecule that enters the citric acid cycle (Krebs cycle) for further energy production.
Understand that this conversion is catalyzed by the pyruvate dehydrogenase complex, a multi-enzyme complex that performs oxidative decarboxylation of pyruvate.
Note that other pathways like conversion to lactate (lactic acid fermentation) or ethanol (alcoholic fermentation) occur under anaerobic conditions (absence of oxygen), so they are not relevant here.
Recognize that carboxylation of pyruvate to oxaloacetate by pyruvate carboxylase is an anaplerotic reaction to replenish citric acid cycle intermediates, but it is not the primary fate of pyruvate under aerobic conditions.
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