The Formation of GTP from GDP in the Citric Acid

Question

The formation of GTP from GDP in the citric acid cycle is an example of
A) substrate-level phosphorylation.
B) oxidative phosphorylation.
C) decarboxylation.
D) cellular respiration.
E) aerobic metabolism.

Accepted Answer

The formation of GTP from GDP in the citric acid cycle is an example of substrate-level phosphorylation, as a phosphate group is directly transferred from a substrate (GDP) to ADP, forming ATP/GTP. It does not involve the electron transport chain or oxidative phosphorylation, which occurs in the inner mitochondrial membrane during aerobic metabolism. Decarboxylation is the removal of a carboxyl group from a molecule, which occurs in several steps of the citric acid cycle. Cellular respiration refers to the overall process of producing ATP from food molecules, which includes the citric acid cycle, but also includes other processes such as glycolysis and oxidative phosphorylation.