Exemplar Problems

Question:

Describe the key steps involved in the citric acid cycle (Krebs cycle).

Answer:

• The citric acid cycle, or Krebs cycle, is a series of enzymatic reactions that occur in the mitochondria. The key steps include:

• Acetyl-CoA, a two-carbon compound, combines with a four-carbon compound called oxaloacetate to form citric acid (a six-carbon compound).

• Through a series of reactions, citric acid is gradually oxidized, releasing carbon dioxide and transferring high-energy electrons to carrier molecules like NADH and FADH2.

• ATP is produced through substrate-level phosphorylation.

• Oxaloacetate is regenerated, and the cycle can continue.