What is the net gain of ATP produced from glycolysis?

Glycolysis is the metabolic pathway that takes place in the cytoplasm of the cell and is the first step of cellular respiration. During glycolysis, one molecule of glucose (which contains six carbon atoms) is broken down into two molecules of pyruvate (each containing three carbon atoms).

In this process, a total of four ATP molecules are produced through substrate-level phosphorylation. However, two ATP molecules are consumed in the early steps of glycolysis to facilitate the phosphorylation of glucose and its derivatives. Therefore, when we calculate the net gain of ATP produced, we subtract the two ATP molecules used from the four produced, resulting in a net gain of two ATP molecules. This net gain is crucial because it represents the energy available for the cell after the initial investment of ATP that is needed to start the glycolytic process.

Additionally, it's important to note that the two NADH molecules generated during glycolysis can also contribute to further ATP production in the electron transport chain, but they are not included in the calculation of the net gain of ATP from glycolysis itself.