The ETC carries out catabolic reactions that occur in the inner mitochondrial membrane. In the ETC hydrogen’s are removed during oxidation and are combined with the O2 to form water. The energy that is released from this reaction is utilized to attach phosphate groups to ADP, which forms the desired product of ATP. This process is defined as oxidative phosphorylation. Cofactors along the membrane of the mitochondria are the primary tools used for the ETC; these can be referred to as different complexes I-V.
Respiration can be defined as the oxidation of the end products of glycolysis with the storage of the energy in the form of ATP. Cellular respiration occurs when oxygen is available, and the products are carbon dioxide and water. There are three main pathways in the cellular respiration process. These are: pyruvate oxidation, the citric acid cycle, and the respiratory chain. Pyruvate oxidation in eukaryotic cells occurs inside the mitochondrion in the inner membrane, and in prokaryotes on the inner face of the plasma membrane.
These NADH and FADH2 molecules are oxidized during oxidation phosphorylation and the electron transport chain and generate water, H2O and ATP (Voet et al. 2006. p. 397). Intermediates formed from the citric acid cycle are important precursors and building blocks for producing important materials in an organism. These intermediates are drained from the TCA cycle in cataplerotic reactions to synthesize important products such as glucose, fatty acids, and amino acids. For example, gluconeogenesis, the synthesis of glucose, requires oxaloacetate that has been converted to malate, while fatty acid biosynthesis utilizes acetyl CoA, and amino acid biosynthesis utilizes oxaloacetate and α -ketoglutarate (Tymoczko, J. L., Berg, J. M., & Stryer, L. 2013. p. 339).
The third route for pyruvate degradation is directly to acetate by pyruvate oxidase. Phosphoenolpyruvate, which also is a product of glycolysis, can too enter the mixed acid fermentation. It can form pyruvate and a molecule of ATP or form oxaloacetate in the presence of carbon dioxide by phosphoenolpyruvate carboxylase. Oxaloacetate is then hydrogenated by malate dehydrogenase and NADH to malate and NAD+. The enzyme fumarase turns malate into fumarate and water.
The inner membrane is a more significant barrier and specific transport proteins exist to carry pyruvate and fatty acids into the matrix. Once inside the matrix, pyruvate and fatty acids are converted to the two carbon compound acetyl coenzyme A (acetyl CoA). For pyruvate this involves a decarboxylation step which removes one of the three carbons of pyruvate as carbon dioxide. The energy released by the oxidation of pyruvate at this stage is used to reduce NAD to NADH. (185) The C2 acetyl CoA is then taken into a sequence of reactions known as Krebs cycle which completes the oxidation of carbon and regenerates an acceptor to keep the cycle going.
Finally, during TCA-8, NADH is formed and OAA is regenerated. The total numbers of products per acetyl CoA are: 2 CO2, 3 NADH, 1 FADH2, and 1 ATP. The numbers of products per glucose are: 4 CO2, 6 NADH, 2 FADH2, and 2 ATP. Specific enzymes exist for this process as well. First, Acetyl CoA is changed to Citrate by Citrate Synthase, then Citrate is changed to Isocitrate by Aconitase.
This is because the coenzyme is released by hydrolysis from the molecule so that it combines with another acetic acid molecule to begin the Krebs cycle again (Reece, Urry, Cain, Wasserman, Minorsky, & Jackson, 2011). The citric acid molecule undergoes an isomerisation of citrate in the second step in the process of the Krebs cycle in metabolism. Reece et al. (2011) defined isomer as “The isomer is one of several compounds with the same molecular formula but different structures and therefore different properties. There are three types of isomers are structural isomers, cis-trans isomers, and enantiomers” (p. 108).
B. Lipids are converted to their substituents, glycerol and fatty acids. Glycerol is converted to dihydroxyacetone phosphate, an intermediatein glycolysis, and fatty acids to acetate and then acetyl CoA in the mitochondria. In both cases, further oxidation to CO2 and release of energy of energy then occur. C. Proteins are hydrolyzed to their amino acid building blocks. The 20 amino acids feeds into glycosis or the citric acid cycle at different points.
The catalyst, sulfuric acid, is dissolved in methanol and then mixed with the pretreated oil. Once the mixture is heated and stirred, the free fatty acids are converted to biodiesel. The final step of esterification is to dewater and feed the product to the transesterification process. 2.1.2. Transesterification Used oil as a feedstock which contains small amount of free fatty acid is fed directly to the transesterification process.
(HallyHosting, n.d) The next stage of glycolysis occurs in thecytoplasm of the mitochondria. This is called the link reaction, also known as oxidative carboxylation. Oxygen is required in this stage so is an aerobic respiration and completes the conversion of pyruvate. The 2 pyruvic acid molecules, or also known as pyruvate, enter into the mitochondria, where the hydrogen and carbon dioxide become removed from them creating t... ... middle of paper ... ...oup to be added to ADP. This then forms ATP.