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MBBS QUESTION #10343
Question 1
Under anaerobic conditions (e.g., vigorous exercise, or red blood cells which lack mitochondria entirely), pyruvate generated by glycolysis is converted to lactate by which enzyme, regenerating the NAD+ required to sustain ongoing glycolysis?
  • Lactate dehydrogenase✔️
  • Pyruvate dehydrogenase
  • Pyruvate carboxylase
  • Pyruvate kinase
Correct Answer Explanation
Lactate dehydrogenase reduces pyruvate to lactate while oxidizing NADH back to NAD+, allowing glycolysis (which requires NAD+ at the glyceraldehyde-3-phosphate dehydrogenase step) to continue functioning even without oxygen or functioning mitochondria.