What is the net ATP yield during glycolysis?

During glycolysis, one molecule of glucose is converted into two molecules of pyruvate. This metabolic pathway occurs in the cytoplasm and involves several key steps that result in both the investment and generation of ATP.

Initially, two ATP molecules are consumed in the early steps of glycolysis to help convert glucose into fructose-1,6-bisphosphate. This investment is necessary to prepare the glucose for subsequent cleavage and further breakdown. As glycolysis continues, four ATP molecules are produced through substrate-level phosphorylation, where phosphate groups are transferred directly to ADP to form ATP.

When calculating the net yield, you subtract the ATP that was used from the ATP that was produced. Therefore, from the four ATP produced, two ATP are used, leading to a net yield of two ATP molecules for each molecule of glucose that undergoes glycolysis. This net gain is crucial for cells, as it provides some energy that can be used for various cellular processes.

Hence, the net ATP yield during glycolysis is indeed two ATP molecules.