How many ATP molecules are produced during glycolysis per glucose molecule?

During glycolysis, a single molecule of glucose is processed to produce energy. The overall reaction of glycolysis begins with one glucose molecule and ends with two molecules of pyruvate. Throughout this process, energy is captured in the form of ATP and NADH.

Glycolysis produces a total of four ATP molecules via substrate-level phosphorylation. However, it is important to consider that two ATP molecules are used during the initial steps of glycolysis to phosphorylate glucose and its intermediates. Thus, the net gain in ATP from one glucose molecule is four ATP produced minus two ATP consumed, which gives a net total of two ATP molecules.

This net production of two ATP per glucose molecule highlights glycolysis as a critical first step in cellular respiration, providing a relatively quick and efficient means of generating ATP in the absence of oxygen while yielding pyruvate for further energy extraction pathways, such as the Krebs cycle and oxidative phosphorylation.