Multiple Choice
In eukaryotic cells, where does the Krebs (citric acid) cycle primarily take place?
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Review 3: Pyruvate & Fatty Acid Oxidation, Citric Acid Cycle, & Glycogen Metabolism
Citric Acid Cycle 1
Multiple Choice
In aerobic metabolism of one molecule of glucose, which pathway produces the greatest total number of NADH molecules (including NADH produced by its associated reactions)?
A
Citric acid cycle (including the pyruvate dehydrogenase step)
B
Beta-oxidation of fatty acids
C
Pentose phosphate pathway (oxidative phase)
D
Glycolysis
Verified step by step guidance1
Identify all the major pathways involved in aerobic metabolism of glucose: glycolysis, pyruvate dehydrogenase complex (link reaction), and the citric acid cycle (TCA cycle).
Determine the number of NADH molecules produced in each pathway per one molecule of glucose. Remember that glycolysis produces NADH in the cytoplasm, pyruvate dehydrogenase converts pyruvate to acetyl-CoA producing NADH, and the citric acid cycle produces NADH during multiple steps.
Calculate the total NADH yield from glycolysis: consider that one glucose molecule produces two molecules of pyruvate, and glycolysis produces NADH per glucose molecule.
Calculate the NADH produced by the pyruvate dehydrogenase step: since each glucose yields two pyruvate molecules, multiply the NADH produced per pyruvate by two.
Calculate the NADH produced in the citric acid cycle per acetyl-CoA and multiply by two (since two acetyl-CoA molecules are generated per glucose). Sum all NADH from glycolysis, pyruvate dehydrogenase, and the citric acid cycle to find which pathway produces the greatest total NADH.
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