Metabolic Process and Oxidative Phosphorylation

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Oxidative phosphorylation occurs in the aerobic metabolic process. Oxidative phosphorylation is a metabolic pathway (a series of chemical reactions occurring within a cell) that uses energy released by the oxidation to produce adenosine triphosphate (ATP). ATP is a multifunction nucleotide used in cells as a coenzyme. It is often referred to as the “molecular unit of currency.” It is an organic compound composed of adenine, the sugar ribose and three phosphate groups.

Aerobic metabolism is a process that involves oxygen in the breakdown of glucose to energy as part of cellular respiration. It can be defined as energy producing “ATP pathways” where the ultimate acceptor of electrons is oxygen. The main differences between aerobic metabolism and anaerobic metabolism is that in aerobic metabolism coenzymes such as NADs carry the electrons. In anaerobic metabolism, pyruvic acid is the final electron acceptor. In aerobic metabolism, there are a number of steps involved in converting glucose into a usable form of energy known as adenosine triphosphate.

The first step is called glycolysis. It is one of the ancient metabolic pathways in living cells and occurs within the cytoplasm of the cell. Glycolysis is the conversion of glucose to pyruvate. It produces two units of ATP for every one glucose molecule. The free energy released in this process is used to form the high energy compounds ATP and NADH (reduced nicotinamide adenine dinucleotide). This process involves 10 reactions in a definite sequence. Glycolysis is known to be the archetype of the universal metabolic pathway. It is a central pathway for the catabolism of carbohydrates in which the six-carbon sugars are split into three-carbon compounds. The subsequent release of energy is used to transform ADP to ATP. It occurs in both aerobic and anaerobic variations.

The next step is pyruvate to acetyl-coA to enable entry into the Kreb’s/TCA/Citric Acid cycle in order to generate two more ATP molecules as well as other byproducts. 34 more ATP are produced by aerobic pathways if oxygen is present. These byproducts are useful in the end-stage generation of ATP (e.g. reducing agent such as NADH, FADH2 and CO2). During the formation of acetyl-coA, NADH is produced from NAD+2H (oxidation). The formation of acetyl-coA and the Kreb’s cycle occur within the mitochondrial matrix. The mitochondrial matrix is the substance occupying the space enclosed by the inner membrane of mitochondrion. It contains enzymes, filaments of DNA, ribosomes, granules, and inclusion of protein crystals, glycogen and lipid.

The final step is where the most energy productive process occurs. The last process is called oxidative phosphorylation and the electron transport chain. These occur within the intermembrane space of the mitochondria within a cell. The ATP amount derived from oxidative phosphorylation is approximately 32. The total yield of aerobic cellular respiration is around 36-38. The oxid-phosph is thus the greatest contributory process to energy production.

Aerobic metabolism occurs in the mitochondria. A mitrochondrion is a membrane-enclosed organelle found in most eukaryotic cells. An organelle is a specialized subunit within a cell that has a specific function and is usually separately enclosed within it own lipid bilayer. A eukaryote is an organism whose cells contain complex structures enclosed within membranes. Mitchondria are commonly referred to as “cellular power plants.” The reason they earned this name is because they generate most of the cell’s supply of ATP as discussed above. How many mitochondria are found in cells varies depending on the organism and tissue. The number can range from one to several thousands. The number of proteins found in the mitochondria also varies. In humans there are 615 unique types of proteins.

Resource by T.Price

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