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Oxidative phosphorylation – The last stage of the aerobic system produces the largest yield of ATP – a total of 34 ATP molecules. It is called oxidative phosphorylation because oxygen is the final acceptor of electrons and hydrogen ions (hence oxidative) and an extra phosphate is added to ADP to form ATP (hence phosphorylation ).
Oxidative phosphorylation in the eukaryotic mitochondrion is the best-understood example of this process. The mitochondrion is present in almost all eukaryotes, with the exception of anaerobic protozoa such as Trichomonas vaginalis that instead reduce protons to hydrogen in a remnant mitochondrion called a hydrogenosome .
One such pathway is oxidative phosphorylation (OXPHOS) within the electron transport chain (ETC). Various inhibitors can downregulate the electrochemical reactions that take place at Complex I, II, III, and IV, thereby preventing the formation of an electrochemical gradient and downregulating the movement of electrons through the ETC.
The first two steps of the urea cycle take place within the mitochondrial matrix of liver and kidney cells. In the first step ammonia is converted into carbamoyl phosphate through the investment of two ATP molecules. This step is facilitated by carbamoyl phosphate synthetase I.
In this process, two electrons generated from NADH, and an accompanying H +, are attached to oxaloacetate to form malate. Once malate is formed, the first antiporter (malate-alpha-ketoglutarate) imports the malate from the cytosol into the mitochondrial matrix and also exports alpha-ketoglutarate from the matrix into the cytosol simultaneously.
The overall process of creating energy in this fashion is termed oxidative phosphorylation. The same process takes place in the mitochondria, where ATP synthase is located in the inner mitochondrial membrane and the F 1-part projects into the mitochondrial matrix. By pumping proton cations into the matrix, the ATP-synthase converts ADP into ATP.
Production of mitochondrial ROS, mitochondrial ROS. Mitochondrial ROS (mtROS or mROS) are reactive oxygen species (ROS) that are produced by mitochondria. [1] [2] [3] Generation of mitochondrial ROS mainly takes place at the electron transport chain located on the inner mitochondrial membrane during the process of oxidative phosphorylation.
is, in essence, the same as the electron transport chain in chloroplasts. The mobile water-soluble electron carrier is cytochrome c 6 in cyanobacteria, having been replaced by plastocyanin in plants. [8] Cyanobacteria can also synthesize ATP by oxidative phosphorylation, in the manner of other bacteria. The electron transport chain is