In which step of glycolysis is NAD+ converted to NADH?

In glycolysis, the conversion of NAD+ to NADH occurs during the sixth step, where glyceraldehyde-3-phosphate (G3P) is oxidized. In this reaction, G3P is dehydrogenated by the enzyme glyceraldehyde-3-phosphate dehydrogenase. During this process, a molecule of NAD+ is reduced to NADH, and one inorganic phosphate (Pi) is added to the oxidized substrate to form 1,3-bisphosphoglycerate.

This step is crucial because NADH serves as a key electron carrier that is utilized in later stages of cellular respiration, particularly in the electron transport chain, where it plays an important role in the production of ATP. Additionally, the generation of NADH in glycolysis is essential for the continuation of the glycolytic pathway, as it helps regenerate NAD+ in anaerobic conditions through fermentation pathways.

Understanding this conversion is vital for grasping how glycolysis connects to broader metabolic pathways and the importance of NAD+ as a cofactor in oxidation-reduction reactions within cellular metabolism.