Question

Which one of the following, involving transfer of a phosphate group, is an example of substrate-level phosphorylation?

• A. ATP to phosphoenolpyruvate
• B. GTP to ADP
• C. ATP to lipids
• D. phosphoenolpyruvate to ADP

Hint:

Substrate-level phosphorylation involves the direct transfer of a phosphate group from a substrate to ADP, forming ATP.

Answer 1

The Correct Option is D

Step 1: Understanding substrate-level phosphorylation.
Substrate-level phosphorylation is a process where a phosphate group is directly transferred from a substrate molecule to ADP, forming ATP. This occurs without the involvement of the electron transport chain or oxidative phosphorylation.

Step 2: Analyzing the options.
(A)ATP to phosphoenolpyruvate: Correct — In this reaction, a phosphate group is transferred to phosphoenolpyruvate, a key step in glycolysis and other metabolic pathways, illustrating substrate-level phosphorylation.
(B)GTP to ADP: This is a transfer of phosphate but not from a substrate molecule directly to ADP, making it incorrect for substrate-level phosphorylation.
(C)ATP to lipids: This is not a case of phosphorylation; it is related to lipid synthesis, making it incorrect.
(D)phosphoenolpyruvate to ADP: While phosphoenolpyruvate is involved in a phosphorylation reaction, it's not the correct form of substrate-level phosphorylation as described in this question.

Step 3: Conclusion.
The correct answer is (A)ATP to phosphoenolpyruvate, as it exemplifies substrate-level phosphorylation.