The process of breaking down glucose is called glycolysis. This metabolic pathway occurs in the cytoplasm of cells, where glucose is converted into pyruvate, yielding a small amount of ATP (adenosine triphosphate) and NADH. Glycolysis is the first step in cellular respiration and can function both aerobically and anaerobically. This process is essential for energy production, as it facilitates the extraction of energy from glucose, with further oxidation occurring in the presence of oxygen.