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Photosystem II (or water-plastoquinone oxidoreductase) is the first protein complex in the light-dependent reactions of oxygenic photosynthesis. It is located in the thylakoid membrane of plants, algae, and cyanobacteria. Within the photosystem, enzymes capture photons of light to energize electrons that are then transferred through a variety ...
All organisms produce a phosphate compound, ATP, which is the universal energy currency of life. In photophosphorylation, light energy is used to pump protons across a biological membrane, mediated by flow of electrons through an electron transport chain. This stores energy in a proton gradient. As the protons flow back through an enzyme called ...
Photosystem I contains a pair of chlorophyll a molecules, designated P700, at its reaction center that maximally absorbs 700 nm light. Photosystem II contains P680 chlorophyll that absorbs 680 nm light best (note that these wavelengths correspond to deep red – see the visible spectrum). The P is short for pigment and the number is the ...
Photosynthetic reaction centre. Electron micrograph of a 2D crystal of the LH1-Reaction center photosynthetic unit. A photosynthetic reaction center is a complex of several proteins, pigments, and other co-factors that together execute the primary energy conversion reactions of photosynthesis. Molecular excitations, either originating directly ...
Photosystem. Photosystems are functional and structural units of protein complexes involved in photosynthesis. Together they carry out the primary photochemistry of photosynthesis: the absorption of light and the transfer of energy and electrons. Photosystems are found in the thylakoid membranes of plants, algae, and cyanobacteria.
Nicotinamide adenine dinucleotide phosphate, abbreviated NADP[1][2] or, in older notation, TPN (triphosphopyridine nucleotide), is a cofactor used in anabolic reactions, such as the Calvin cycle and lipid and nucleic acid syntheses, which require NADPH as a reducing agent ('hydrogen source'). NADPH is the reduced form, whereas NADP + is the ...
P680, or photosystem II primary donor, is the reaction-center chlorophyll a molecular dimer associated with photosystem II in plants, algae, and cyanobacteria, and central to oxygenic photosynthesis. Etymology
Ferredoxin: NADP + reductase is the last enzyme in the transfer of electrons during photosynthesis from photosystem I to NADPH. [2] The NADPH is then used as a reducing equivalent in the reactions of the Calvin cycle. [2] Electron cycling from ferredoxin to NADPH only occurs in the light in part because FNR activity is inhibited in the dark. [11]