Question

During the process of glycolysis, which of the following substrates donates electrons to NAD+ and adds Pi to form 1,3-bisphosphoglycerate?

A) 3-phosphoglycerate
B) 2-phosphoglycerate
C) glyceraldehyde-3-phosphate
D) glucose
E) glucose-6-phosphate

Answer 1

Glyceraldehyde-3-phosphate is the substrate that donates electrons to NAD+ and adds Pi to form 1,3-bisphosphoglycerate during glycolysis, via the action of glyceraldehyde-3-phosphate dehydrogenase.

Step-by-step explanation:

During the process of glycolysis, the substrate that donates electrons to NAD+ and adds Pi (inorganic phosphate) to form 1,3-bisphosphoglycerate is glyceraldehyde-3-phosphate (C). The reaction is catalyzed by the enzyme glyceraldehyde-3-phosphate dehydrogenase, which oxidizes glyceraldehyde-3-phosphate by transferring high-energy electrons to NAD+ to produce NADH. In association with this electron transfer, an inorganic phosphate group is added to the oxidized glyceraldehyde-3-phosphate to produce 1,3-bisphosphoglycerate. This process is crucial for the energy yield of glycolysis, leading to the eventual production of ATP.

1,3-bisphosphoglycerate then donates a high-energy phosphate to ADP, catalyzed by phosphoglycerate kinase, resulting in the formation of ATP and 3-phosphoglycerate. This step is an example of substrate-level phosphorylation. Eventually, pyruvate is formed as the end product of glycolysis, with the energy state of the cell determining the fate of this three-carbon molecule.