Glucose is phosphorylated using ATP to form glucose-6- phosphate. This keeps the glucose in the cell as it cannot exit through glucose transporters and commits the glucose molecule to glycolysis. Phosphorylation also makes the glucose more reactive.Glucose-6-phosphate is isomerised to fructose phosphate. Another phosphate group is added from ATP and fructose-1,6-bisphosphate is formed. This breaks down into 2 triose phosphate molecules. The triose phosphate is converted into 2 pyruvate molecules NAD is reduced, and ATP is formed when a phosphate group is transferred from an intermediate directly to ADP. The formation of ATP in this way is called substrate level phosphorylation.