What is regenerated in alcoholic fermentation?

In alcoholic fermentation, the regeneration of NAD+ is a critical process that allows glycolysis to continue. During glycolysis, glucose is broken down into pyruvate, producing a small amount of ATP and reducing NAD+ to NADH in the process. For glycolysis to continue producing ATP under anaerobic conditions (when oxygen is not available), NADH must be converted back into NAD+.

In alcoholic fermentation, this regeneration occurs when pyruvate is converted into ethanol and carbon dioxide. Specifically, as pyruvate is transformed into acetaldehyde and then into ethanol, NADH donates its electrons, resulting in the conversion back to NAD+. This regeneration of NAD+ is essential because it ensures a steady supply of NAD+ is available for glycolysis, thereby allowing cells to continue producing energy in the form of ATP even in the absence of oxygen.

Other options are involved in different pathways of cellular metabolism, but only NAD+ is specifically regenerated in the context of alcoholic fermentation.