What is the energy investment phase of glycolysis?

The energy investment phase of glycolysis consists of the first five steps, where two ATP molecules are consumed to activate glucose. In the first step, glucose is phosphorylated by hexokinase to form glucose-6-phosphate. In the third step, fructose-6-phosphate is further phosphorylated to fructose-1,6-bisphosphate by phosphofructokinase-1. These steps prepare the glucose molecule for further breakdown and energy production.