Mitochondria :: essays research papers

MitochondriaMitochondria are responsible for energy production. They are also theresponsible reparation for which respiration takes place. Mitochondria containenzymes that help convert food material into adenosine triphosphate (ATP), whichcan be used directly by the cell as an energy source. Mitochondria run for to beconcentrated near cellular structures that require large inputs of energy, suchas the flagellum. The role of the mitochondria is very important in respiration.In the presence of oxygen, pyruvate or fatty acids, can be furtheroxidized in the mitochondria. Each mitochondrion is enclosed by two membranesseparated by an intermembrane space. The intermembrane space extends into thefolds of the internal membrane called cristae which dramatically increase thesurface area of the upcountry membrane. Cristae extend into a dense material calledthe matrix, an area which contains RNA, DNA, proteins, ribosomes and range ofsolutes. This is similar to the contents of the chloroplast stroma and care thechloroplast, the mitochondrion is a semi-autonomous organelles containing themachinery for the production of some of its own proteins. The main function ofthe mitochondrion is the oxidation of the pyruvate derived from glycolysis andrelated processes to produce the ATP required to perform cellular work.(Campbell182-9)Pyruvate, or fatty acids from the breakdown of triglycerides orphospholipids, pass easily through pores in the outer mitochondrial membranemade up of a channel protein called porin. The inner membrane is a moresignificant barrier and specific transport proteins exist to carry pyruvate andfatty acids into the matrix. Once inside the matrix, pyruvate and fatty acidsare reborn to the two carbon compound acetyl coenzyme A (acetyl CoA). Forpyruvate this involves a decarboxylation step which removes one of the threecarbons of pyruvate as carbon dioxide. The energy released by the oxidation ofpyruvate at this stage is used to reduce NAD to NADH. (185)The C2 acetyl CoA is then taken into a sequence of reactions known asKrebs cycle which completes the oxidation of carbon and regenerates an acceptorto have got the cycle going. The oxidation of the carbon is accompanied by thereduction of electron acceptors and the production of some ATP by substratephosphorylation. The C2 acetyl CoA is coupled to oxaloacetate, a C4 acceptor inthe cycle. The product is citrate a C6 compound. This first product, citrate,is the reason the cycle is sometimes called the citric acid or ticarboxylic acidcycle, referring it after the scientist whose lab virtually advanced ourunderstanding of it, Sir Hans Krebs. (Comptons 160)Two of the early reactions of the cycle are decarboxylations whichshorten citrate to succinate a C4 compound.