Exemplar Problems

Question:

Explain the role of substrate-level phosphorylation in the Krebs Cycle and identify the specific steps in which it occurs.

Answer:

Substrate-level phosphorylation in the Krebs Cycle involves the direct transfer of a phosphate group to ADP, forming ATP (or GTP). This occurs in two steps:

• The conversion of succinyl-CoA to succinate, catalyzed by succinyl-CoA synthetase, produces one molecule of GTP (or ATP).

• This step occurs during the Krebs Cycle and contributes to cellular energy production.