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Oxidative phosphorylation (UK / ɒ k ˈ s ɪ d. ə. t ɪ v /, US / ˈ ɑː k. s ɪ ˌ d eɪ. t ɪ v / [1]) or electron transport-linked phosphorylation or terminal oxidation is the metabolic pathway in which cells use enzymes to oxidize nutrients, thereby releasing chemical energy in order to produce adenosine triphosphate (ATP).
In the process of photosynthesis, the phosphorylation of ADP to form ATP using the energy of sunlight is called photophosphorylation. Cyclic photophosphorylation occurs in both aerobic and anaerobic conditions, driven by the main primary source of energy available to living organisms, which is sunlight.
The leaf is the primary site of photosynthesis in plants. There are four main factors influencing photosynthesis and several corollary factors. The four main are: [113] Light irradiance and wavelength; Water absorption; Carbon dioxide concentration; Temperature. Total photosynthesis is limited by a range of environmental factors.
Free oxygen is produced in the biosphere through photolysis (light-driven oxidation and splitting) of water during photosynthesis in cyanobacteria, green algae, and plants. During oxidative phosphorylation in cellular respiration, oxygen is reduced to water, thus closing the biological water-oxygen redox cycle.
Cyclic phosphorylation is important to create ATP and maintain NADPH in the right proportion for the light-independent reactions. The net-reaction of all light-dependent reactions in oxygenic photosynthesis is: 2 H 2 O + 2 NADP + + 3ADP + 3P i → O 2 + 2 H + + 2NADPH + 3ATP. PSI and PSII are light-harvesting complexes.
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.
The pathway is especially important in red blood cells (erythrocytes). The reactions of the pathway were elucidated in the early 1950s by Bernard Horecker and co-workers. [2] [3] There are two distinct phases in the pathway. The first is the oxidative phase, in which NADPH is generated, and the second is the non-oxidative synthesis of
The chemical pathway of oxygenic photosynthesis fixes carbon in two stages: the light-dependent reactions and the light-independent reactions. The light-dependent reactions capture light energy to transfer electrons from water and convert NADP + , ADP , and inorganic phosphate into the energy-storage molecules NADPH and ATP .