Aerobic vs Anaerobic Glycolysis
Glycolysis is the first step of ATP formation that takes place in the cytosol outside of the mitochondria, using glucose as the energy source. It occurs in both aerobic and anaerobic environments, and is the only pathway which has the ability to produce ATP in the absence of oxygen. Therefore, it can be seen in the organisms like prokaryotes, cells like erythrocytes, and in hypoxic environments such as rapidly contracting muscle tissue or ischaemic tissue that lack mitochondria. The process of glycolysis can be divided into aerobic or anaerobic glycolysis, depending on the oxygen availability of the environment it takes place. However, in both processes, the starting source is glucose and end product is pyruvate.
(Image Source: “Anaerobic vs. Aerobic pathways” SparkNotes.com. SparkNotes LLC. n.d.. Web. 13 Sept. 2013.)
Aerobic glycolysis is the glycolytic pathway which occurs in the cytosol in the presence of oxygen. When compared to anaerobic glycolysis, this pathway is much more efficient and produces more ATP per glucose molecule. In aerobic glycolysis, the end product, pyruvate is transferred to mitochondria for the initiation of Citric acid cycle. Therefore, the ultimate products of aerobic glycolysis are 34 ATP molecules, water, and carbon dioxide.
Anaerobic glycolysis takes place in the cytoplasm when a cell lacks oxygenated environment or lacks mitochondria. In this case, NADH is oxidized to NAD+ in the cytosol by converting pyruvate into lactate. Anaerobic glycolysis produces (2 lactate + 2 ATP + 2 H2O + 2 H+) from one glucose molecule. Unlike the aerobic glycolysis, anaerobic glycolysis produces lactate, which reduces the pH and inactivates the enzymes.
What is the difference between Aerobic and Anaerobic Glycolysis?
• Aerobic glycolysis occurs in oxygen rich environments, whereas anaerobic glycolysis occurs in oxygen lack environments.
• Aerobic glycolysis is more efficient than anaerobic glycolysis; hence it produces a large amount of ATP than anaerobic glycolysis.
• Aerobic glycolysis occurs only in eukaryotes while anaerobic glycolysis occurs in both prokaryotes and eukaryotes.
• Unlike in anaerobic glycolysis, the end product of Aerobic glycolysis (pyruvate) is used to initiate other pathways in mitochondria.
• Anaerobic glycolysis produces 2ATPs per glucose molecule while aerobic glycolysis produces 36 to 38 ATPs per glucose molecule.
• Ultimate end product of anaerobic glycolysis is lactate, which may be harmful to the cell itself, whereas that of aerobic glycolysis is water and carbon dioxide, which are not harmful to cells.
• Unlike in anaerobic glycolysis, NADH + H+ undergo oxidative phosphorylation in the presence of oxygen in aerobic glycolysis.
• Pyruvate is reduced to lactate during anaerobic glycolysis whereas, during aerobic glycolysis, pyruvate is oxidation to acetyl coenzyme A (acetyl- CoA).