The role of glycolysis in cellular metabolism is to initiate the process of breaking down glucose for energy production. This process occurs in the cytoplasm of cells and does not require oxygen (anaerobic). Glycolysis converts one molecule of glucose into two molecules of pyruvate, producing a net gain of two molecules of ATP and two molecules of NADH. These products are crucial as they provide energy and electrons for subsequent energy-producing processes, either through aerobic respiration or fermentation. Glycolysis is therefore a key step in cellular metabolism.