Krebs cycle Transitional Reasoning Download PDF

Questions

1. 1.

   A research team investigating metabolic pathways treats isolated active mitochondria with malonate, a competitive inhibitor of the enzyme succinate dehydrogenase. As the reaction proceeds in the presence of adequate acetyl-CoA and initial cycle intermediates, the researchers monitor the concentrations of intermediates and coenzymes. Based on the reaction sequence of the Krebs cycle, which metabolic outcome will be observed as a direct result of this inhibition?

   • A) Fumarate and malate accumulate rapidly, sustaining the continuous regeneration of oxaloacetate.
   • B) Citrate synthesis accelerates because accumulated succinyl-CoA directly stimulates citrate synthase.
   • C) Succinate accumulates in the matrix, while the reduction of FAD to FADH2 and oxaloacetate regeneration cease.
   • D) Carbon dioxide release halts immediately at the first step, preventing the formation of any six-carbon intermediates.