ATP production can be very quick and short-lived, as in the case of creatine phosphate. Creatinine, a a nitrogenous waste, is produced from this anaerobic respiration process. Glycolysis generates about 45 seconds of sustained ATP energy, using glucose as its fuel. Pyruvate can be fermented into lactate, which can actually be converted back into pyruvate later, or be expelled into the bloodstream. The citric acid cycle uses Acetyl CoA generated from carbon compounds (carbs, fats, or proteins) in order to produce great deals of ATP using the electron transport chain and oxygen as a final electron acceptor. Carbon dioxide is released as a waste product from aerobic cellular respiration. Find diagrams, notes, and practice questions at www.sciencewithsusanna.com