Aerobioc Respiration and Photosynthesis essays

Aerobioc Respiration and Photosynthesis essays Aerobic Respiration is the sixth and final event in the history of metabolism. This cellular process harvests energy by stripping energetic electrons from organic molecules. Aerobic respiration is the portion of cellular respiration that requires oxygen as an electron acceptor. Aerobic respiration employs the same kind of proton pump as photosynthesis and is thought to have evolved as a modification of the basic photosynthetic machinery. It was perhaps inevitable that among the descendants of these respiring photosynthetic bacteria, some would eventually do without photosynthesis entirely, subsisting only on the energy and hydrogen derived from the breakdown of organic molecules. The mitochondria within all eukaryotic cells are thought to be descendants of this bacteria. The process of aerobic respiration is quite simple. The energy of a chemical bond is contained in the potential energy of the electrons that make up the bond. Cells harvest this energy by breaking the bonds and shifting the electrons from one molecule to the next. During each transfer, the electrons lose some of their energy. At the end of this process, the high-energy electrons from the initial chemical bonds have lost much energy, and these depleted electrons are to the final electron acceptor, which is oxygen. In aerobic respiration, the cells harvest energy from glucose molecules in a sequence of four major pathways: glycolysis, pyruvate oxidation, the Krebs cycle, and the electron transport chain. Oxygen is the final electron acceptor. To harvest energy, the cells carry out a complex series of enzyme-catalyzed reactions that occur in four stages. The first stage captures energy by substrate-level phosphorylation through glycolysis; the next three stages carry out aerobic respiration by oxidating the end product of glycolysis. The difference between aerobic respiration and photosynthesis is that aerobic respiration requires oxygen as an electro...