What occurs during the first step of glycolysis?

During the first step of glycolysis, glucose undergoes phosphorylation, which involves the addition of phosphate groups to the glucose molecule. This reaction is catalyzed by the enzyme hexokinase or glucokinase, depending on the tissue type. The addition of these phosphate groups—one from ATP—converts glucose into glucose-6-phosphate. This step is crucial as it helps to trap glucose inside the cell and also prepares it for further breakdown in subsequent steps of glycolysis.

The reaction consumes one molecule of ATP, which is transformed into ADP in the process. By attaching phosphate groups to glucose, the energy from ATP is utilized, ultimately facilitating the pathway that leads to the production of ATP and NADH in later stages of glycolysis. This early investment of energy helps to regulate the pathway and ensures that glucose is effectively broken down for energy production.