How many ATP molecules are produced during glycolysis?

During glycolysis, the primary process takes place in the cytoplasm of the cell, where one glucose molecule is broken down into two molecules of pyruvate. Throughout this process, a net gain of 2 ATP molecules is produced. Although glycolysis initially consumes 2 ATP molecules to activate glucose, it later produces 4 ATP molecules through substrate-level phosphorylation, leading to a net yield of 2 ATP.

In addition to the ATP produced, glycolysis also generates 2 NADH molecules, which can contribute to further ATP production during oxidative phosphorylation, but those processes occur later in cellular respiration and aren't counted in the net ATP produced directly from glycolysis. Therefore, the total number of ATP molecules produced specifically during glycolysis is accurately represented by the answer indicating the net gain of 2 ATP molecules.