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Biology: Cellular Metabolism Flashcards

7 cards from real DAT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. The pyruvate dehydrogenase complex converts pyruvate into which molecule entering the citric acid cycle?

    Answer: Acetyl-CoA

    Pyruvate is oxidatively decarboxylated to acetyl-CoA, releasing CO2 and producing NADH.

  2. How many CO2 molecules are released per turn of the citric acid cycle?

    Answer: 2

    Isocitrate dehydrogenase and alpha-ketoglutarate dehydrogenase each release one CO2 per turn.

  3. Which molecule combines with acetyl-CoA to form citrate?

    Answer: Oxaloacetate

    Citrate synthase condenses acetyl-CoA with oxaloacetate to begin the cycle.

  4. Per turn of the citric acid cycle, how many NADH molecules are produced?

    Answer: 3

    Three NADH are generated at the isocitrate, alpha-ketoglutarate, and malate dehydrogenase steps.

  5. Which high-energy molecule is produced directly by substrate-level phosphorylation in the citric acid cycle?

    Answer: GTP

    Succinyl-CoA synthetase produces GTP (or ATP) by substrate-level phosphorylation.

  6. In which cellular compartment does the citric acid cycle occur?

    Answer: Mitochondrial matrix

    All citric acid cycle enzymes reside in the mitochondrial matrix, except succinate dehydrogenase.

  7. Which citric acid cycle enzyme is also a component of the electron transport chain (Complex II)?

    Answer: Succinate dehydrogenase

    Succinate dehydrogenase is embedded in the inner membrane and feeds FADH2 electrons directly into Complex II.