MDCAT Biology MCQ #173

A chronic alcoholic presents with thiamine deficiency (Vitamin B1). Which enzyme complex's failure prevents pyruvate from entering the Krebs cycle in this patient?

MDCAT Biology MCQ #173

  1. Question 1

    Q1. A chronic alcoholic presents with thiamine deficiency (Vitamin B1). Which enzyme complex's failure prevents pyruvate from entering the Krebs cycle in this patient?

    • A) Isocitrate dehydrogenase
    • B) Succinate dehydrogenase
    • C) Pyruvate dehydrogenase
    • D) Citrate synthase

    Answer: Pyruvate dehydrogenase

    Explanation: Pyruvate decarboxylation requires thiamine pyrophosphate to form Acetyl-CoA; without it, pyruvate cannot enter the Krebs cycle, leading to metabolic failure.