Question

During the second half of glycolysis, what occurs?

a) ATP is consumed.
b) Pyruvate is converted to acetyl-CoA.
c) ATP is generated.
d) Glucose is phosphorylated.

Answer 1

During the second half of glycolysis, ATP is generated as a net gain while glucose metabolites are transformed into pyruvate, also producing NADH along the way. Option c is correct.

Step-by-step explanation:

During the second half of glycolysis, the option that correctly describes what occurs is (c) ATP is generated. In this phase, the glycolytic pathway has already split glucose into two three-carbon molecules. Further reactions convert these molecules into pyruvate, with a net production of ATP.

Specifically, each molecule of glyceraldehyde-3-phosphate that was produced in the previous steps undergoes a series of transformations, which results in the generation of two ATP molecules per glyceraldehyde-3-phosphate. Since there are two such molecules for each glucose, a total of four ATPs are produced.

However, because the initial investment was two ATPs, the net gain is two ATPs per glucose molecule processed. Moreover, this stage also produces NADH, which carries electrons to the electron transport chain if oxygen is present.