Sep 14, 2011 · Lord, Save Me From The Krebs Cycle : Krulwich Wonders... Rap songs and colorful videos try to make science accessible to kids, but a dynamic school teacher could be more effective. The human cycle averages 28 days in length, measured from the beginning of menstruation. The menstrual cycle is, however, quite variable in length, even in the same person from month to month. Variations in the length of the cycle are due principally to variation in the length of the proliferative phase. See: illustration The electron transfer chain, also called the electron transport chain, is a sequence of complexes found in the mitochondrial membrane that accept electrons from electron donors such as NADH[?] or succinate, shuttle these electrons across the mitochondrial membrane creating an electrical and chemical gradient, and through the proton driven chemistry of the ATP synthase (aka the F 0 F 1 particle ... cycle definition: The definition of a cycle is a period of time or complete set of events that repeat. (noun) An example of a cycle is the earth's rotation around the sun.... Krebs cycle. A series of chemical reactions that occur in most aerobic organisms and are part of the process of aerobic cell metabolism, by which glucose and other molecules are broken down in the presence of oxygen into carbon dioxide and water to release chemical energy in the form of ATP.