Which of the following compounds is NOT directly produced in glycolysis?

In glycolysis, which is the metabolic pathway that breaks down glucose to extract energy for cellular metabolism, several key compounds are produced. Among these, NADH, ATP, and pyruvate are directly generated as a result of the glycolytic process.

NADH is produced when glyceraldehyde 3-phosphate is oxidized, capturing electrons and protons that convert NAD+ to NADH. This is a crucial step as it facilitates the subsequent transfer of energy through the electron transport chain.

ATP is produced through both substrate-level phosphorylation during glycolysis, specifically in the steps where 1,3-bisphosphoglycerate and phosphoenolpyruvate donate high-energy phosphate groups to ADP to form ATP.

Pyruvate is the final product of glycolysis, as it is formed from phosphoenolpyruvate through the action of the enzyme pyruvate kinase, representing the end of the glycolytic pathway.

In contrast, FADH2 is not formed during glycolysis. Instead, FADH2 is produced in other metabolic pathways, such as the Krebs cycle (citric acid cycle), where FAD is reduced to FADH2 during the oxidation of succinate to fumarate. Therefore, among the