What happens in the energy investment phase of glycolysis?

The energy investment phase of glycolysis involves the consumption of two ATP molecules. In the first step, glucose is phosphorylated by hexokinase, using one ATP molecule. In the third step, fructose-6-phosphate is further phosphorylated by phosphofructokinase-1 (PFK-1), consuming another ATP. This phase prepares the glucose molecule for subsequent reactions that lead to energy production.