Aerobic Respiration:
* Glycolysis: This is the initial stage and occurs in the cytoplasm. It breaks down glucose into pyruvate, producing a small amount of ATP and NADH. Glycolysis can occur with or without oxygen, but it's more efficient with oxygen present.
* Krebs Cycle (Citric Acid Cycle): This occurs in the mitochondrial matrix. Pyruvate is converted into acetyl-CoA, which enters the cycle. The cycle generates ATP, NADH, FADH2, and carbon dioxide. This step *requires* oxygen.
* Electron Transport Chain: This occurs in the inner mitochondrial membrane. Electrons from NADH and FADH2 are passed down a chain of electron carriers, releasing energy to pump protons across the membrane. This creates a proton gradient that drives ATP synthesis by ATP synthase. This step *requires* oxygen as the final electron acceptor.
Anaerobic Respiration:
* Glycolysis: This is the only stage of cellular respiration that occurs in anaerobic conditions. However, instead of pyruvate entering the Krebs cycle, it undergoes fermentation.
* Fermentation: This process regenerates NAD+ from NADH, allowing glycolysis to continue. There are two main types of fermentation:
* Lactic Acid Fermentation: Pyruvate is converted to lactic acid, which can build up in muscles during intense exercise.
* Alcohol Fermentation: Pyruvate is converted to ethanol and carbon dioxide, a process used by yeast.
In summary:
* Aerobic respiration requires oxygen and produces significantly more ATP (about 36-38 molecules) than anaerobic respiration.
* Anaerobic respiration does not require oxygen and produces only a small amount of ATP (2 molecules).
Let me know if you have any other questions!
