Which metabolic pathway is directly associated with glycolysis?

Glycolysis is a fundamental metabolic pathway in which glucose is broken down into pyruvate, generating a small amount of ATP and reducing equivalents in the form of NADH. The primary connection of glycolysis to fermentation reinforces its role in anaerobic conditions where oxygen is limited. During fermentation, pyruvate, the end product of glycolysis, can be converted into various products such as lactate in animals or ethanol and carbon dioxide in yeast. This process allows glycolysis to continue operating by regenerating NAD+, which is necessary for the glycolytic pathway to proceed under anaerobic conditions.

In contrast, while the citric acid cycle is closely linked to the aerobic breakdown of pyruvate produced by glycolysis, it is not directly part of the glycolytic pathway itself but rather a subsequent route for aerobic respiration. Oxidative phosphorylation occurs later in the metabolic chain where NADH and FADH2 are oxidized, making it indirectly related to glycolysis but not directly associated with it. Fatty acid synthesis, meanwhile, is a completely different pathway involved in the anabolic processes of the body and does not share a direct connection with glycolysis.

Understanding these relationships highlights how fermentation is directly tied to glycolysis, especially in the absence of oxygen,