The Krebs cycle(tricarboxylic acid cycle) named after Sir Hans Krebs, a German biochemist, is a complicated biochemical pathway in which ATP is synthesized from carbohydrates, proteins and fats. All organisms make ATP by breaking covalent bonds of carbohydrates, lipids, and protein. When these bonds are broken stored energy is released. In humans aerobic respiration supplies the oxygen for the process but we can also use the fermentation pathway for short periods when we are not getting enough oxygen. Glycolysis splits glucose into pyruvate molecules, glycolysis continues in the cytoplasm of your cells, the aerobic pathways continue inside the mitochondria. Enzymes catalyze each step in the process. The aerobic pathway yields 36 ATP's. In the Krebs cycle pyruvate is broken down to CO2 and H2O, hydrogen and electrons are stripped and loaded onto coenzymes NAD+ and FAD and are delivered to the electron transport system. O2 accepts the electrons at the end of the transport system.