Exemplar Problems

Question:

Discuss the regulation of the Krebs Cycle, including the key regulatory enzymes and factors that control its activity.

Answer:

The Krebs Cycle is regulated at multiple points:

• Citrate synthase, isocitrate dehydrogenase, and alpha-ketoglutarate dehydrogenase are key regulatory enzymes.

• High levels of ATP, NADH, and succinyl-CoA inhibit these enzymes, while ADP and calcium ions activate them.

• The regulation ensures that the cycle is active when energy demand is high and inhibited when sufficient ATP and NADH are available.