Glycolysis which is where glucose is broken down into 2 molecules of pyruvate releasing 2ATP and 2NADH. Second is the link reaction. This links glycolysis to the Krebs Cycle. Pyruvate molecules are decarboxylated. Pyruvate molecules are oxidized and converted to acetylcoenzyme A. Krebs cycle is made up of a series of chemical reactions to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins into carbon dioxide and chemical energy. Final step is oxidative phosphorylation which is the metabolic pathway in which cells use enzymes to oxidize nutrients, thereby releasing energy which is used to produce adenosine triphosphate (ATP). Oxygen is the final electron acceptor in the electron chain