In the presence of oxygen, the next step following glycolysis is the process of pyruvate oxidation, which leads to aerobic respiration. Glycolysis occurs in the cytoplasm of the cell, and the products of glycolysis (pyruvate) are then transported into the mitochondria, where pyruvate oxidation takes place.
During pyruvate oxidation, each pyruvate molecule (produced from glycolysis) is converted into acetyl-CoA, and in the process, carbon dioxide (CO2) is released, and NAD+ is reduced to NADH. The acetyl-CoA then enters the citric acid cycle (Krebs cycle) for further energy production. The entire process is vital for the efficient extraction of energy from glucose when oxygen is available.