Essay on BIOCHEMISTRY OF CENTRAL CARBON Rate of metabolism
Central carbon metabolic rate works by using series of complicated enzymatic actions to make metabolic precursors. These precursors are then utilized as uncooked products for mobile biomass manufacturing. The central carbon metabolic pathways involve the Embden-Meyerhof-Parnas (EMP) pathway of glycolysis, the pentose phosphate pathway and the citric acid cycle. These pathways present variations from organism to organism, relying around the ecological niche the organism occupies. For instance, Pseudomonas bacterium has an extra central pathway, the Entner-Doudoroff (ED) pathway, which replaces the EMP pathway. In a few species of microbes which include saccharolytic Archaea, carbs are assimilated by means of modified non-phosphorylated ED pathways as they do not need the conventional EMP pathway (Elad, Eran, & Uri, 2010). Embden-Meyerhof-Parnas pathway (EMP) is the most common pathway among many organisms for the conversion of glucose-6-phosphate into pyruvate (Elad et al., 2010). It allows metabolic use of glucose to ATP, NADH ?and pyruvate. The EMP pathway can occur both anaerobically and aerobically by way of the conversion of pyruvate to acetyl CoA (Kellen & Manuel, 2011). Organisms which use carbohydrates other than hexoses as carbon sources have essential glycolytic intermediates synthesized by glyconeogenesis. Organisms like Archaea have unique pathway that is modified from the conservative glyconeogenesis found in bacteria. This unique pathway is presented in a separate subsystem in which out of ten enzymatic actions constituting the classical EMP, seven are reversible and work in glyconeogenesis (Elad et al., 2010). The pentose phosphate pathway is the second type of pathway. The pentose phosphate pathway is the major source for the NADPH required for anabolic processes. It consists of three major phases each characterised by a unique metabolic product. These products can be applied as precursor resources for other pathways depending on the needs of the organism (Elad et al., 2010). Gluconeogenesis is directly linked to the pentose phosphate pathway. Gluconeogenesis oxidizes glucose to generate NADPH and other carbohydrate uncooked supplies applied in mobile biosynthesis. The need for glucose-6-phosphate in the cell increases the activity of gluconeogenesis. During the reduction of NADP to NADPH, glucose?6?phosphate is oxidized by two successive reactions. In the first reaction, the first carbon of glucose is converted from an aldol to an ester by glucose?6?phosphate dehydrogenase. In the second reaction, catalyzed by 6?phosphogluconolactone ? dehydrogenase, the same carbon is further oxidized to CO 2 and released. This leaves behind a 5?carbon sugar, ribulose?5?phosphate (Elad et al., 2010). Lastly is the Krebs cycle. It is also referred to as the citric acid cycle or the tricarboxylic acid (TCA). This cycle consists of an eight series reactions that occur in the mitochondrion of the cell bestessaysforsale.net. In these reactions, a two carbon molecule (acetate) is completely oxidized to carbon dioxide. Besides breaking glucose, Krebs cycle oxidizes all metabolites including sugars, amino acids and fatty acids. Each of these oxidized has a pathway leading into the Krebs cycle. For example, carbs are broken down into acetyl CoA by glycolysis while fatty acids are also oxidized into acetyl CoA by the beta oxidation pathway. The products of Krebs cycle can be employed to make molecules including amino acids and fatty acids (Elad et al., 2010). The central carbon metabolic process consists of enzyme catalyzed reactions that enables organisms to reproduce and maintain their mobile structures. There exist similarities in the basic metabolic pathways and components among organisms. For example, the organic acid intermediates associated with citric acid cycle are present in all known organisms. These similarities not only apply to unicellular organisms for instance micro organism but also large multicellular organisms. These striking similarities in metabolic pathways are attributed to their early manifestation in the evolutionary history. Organisms have only been able to modify for efficiency (Kellen & Manuel, 2011).
References Kellen, L. O., & Manuel, L. (2011). Central carbon fat burning capacity of plasmodium parasites. Molecular and Biochemical Parasitology, 175, 95-103. doi:10.1016/j.molbiopara.2010.09.001 Noor, E., Eden, E., Milo, R., & Alon, U. (2010). Central carbon metabolism as a minimal biochemical walks between precursors for biomass and energy. Molecular Mobile Journal, 39(5), 809-820. doi:10.1016/j.molcel.2010.08.031