Energy yield:
Early in glycolysis there are two ATPs are needed for the conversion of glucose to glucose 6-phosphate through hexokinase and for the conversion of fructose 6- phosphate to fructose 1,6-bisphosphate by PFK. Moreover, fructose 1,6-bisphosphate then provides increase to two three-carbon units, each of that generates two ATPs in subsequent steps (catalyzed through pyruvate kinase and phosphoglycerate kinase) providing a net yield of two ATPs per original glucose molecule described in the figure. The whole reaction is:
![1942_Energy yield.png](https://www.expertsmind.com/CMSImages/1942_Energy%20yield.png)
Note that, under aerobic conditions the two NADH molecules which are synthesized are re-oxidized through the electron transport chain producing ATP. Providing the cytoplasmic situation of these NADH molecules, each is re-oxidized through the glycerol 3-phosphate shuttle and produces around two ATPs during oxidative phosphorylation or through the malate-aspartate shuttle and produces approximately three ATPs during oxidative phosphorylation.