An Account of ATP Production in Living Organisms

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An Account of ATP Production in Living Organisms All cells must do work to stay alive and maintain their cellular environment. The energy needed for cell work comes from the bonds of ATP. Cells obtain their ATP by oxidizing organic molecules, a process called cellular respiration. Glucose is the primary fuel molecule for the cells of living organisms. Every living organism must do cell respiration. Most eukaryotic organisms are aerobic. Aerobic respiration is required in order to obtain enough energy (ATP) from the oxidations of fuel molecules to survive. In aerobic respiration glucose is broken down into water and carbon dioxide. Oxygen is required as the final electron acceptor for the oxidations. [IMAGE]C6H12O6 + 6O2 ï€ 6H2O + 6CO2 + ATP Not all cell respiration is aerobic. All organisms do some type of anaerobic respiration during times of oxygen deficit, although it may not be sufficient to sustain the organism's ATP needs. Fuel molecules oxidized without oxygen yield smaller amounts of ATP. Fermentation involves the partial breakdown of glucose without using oxygen. In aerobic cellular respiration, the final electron acceptor is oxygen, hence, the emphasis on oxygen in aerobic respiration. The initial stage of cell respiration, is a process called glycolysis, which splits a glucose molecule into two molecules of pyruvate, a 3-carbon compound. Glycolysis occurs in the cytoplasm of the cell. What follows glycolysis depends on the presence or absence of oxygen. Glucose uses 2 ATP molecules in the production of hexose phosphate and hexose bisphosphate, thus producing ADP. However, as soon as hexose ... ... middle of paper ... ... of NADH + H+ are produced in both glycolysis and the link reaction and 6 molecules are produced in the KrebÂ’s cycle. Therefore, 30 molecules of ATP are produced from the oxidation of the 10 molecules of NADH + H+. FADH + H+ produces only 2 molecules of ATP. In total 2 molecules of FADH + H+ are produced, both in the KrebÂ’s cycle. Therefore, with the 4 molecules of ATP produced by FADH + H+ in oxidative phosphorylation, and the 30 by NADH + H+ as well as the 4 molecules of ATP produced in earlier stages, a total of 38 molecules of ATP are produced by aerobic respiration. This is 36 more than that produced in anaerobic respiration. This shows why aerobic respiration is so more effective at producing energy than anaerobic respiration and, therefore, why it is used the majority of the time by eukaryotic organisms.

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