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[citation needed] He called them cancroïde, later changing the name to chéloïde to avoid confusion with cancer. The word is derived from the Ancient Greek χηλή, chele, meaning "crab pincers", and the suffix -oid, meaning "like". In the 19th century it was known as the "Keloid of Alibert" as opposed to "Addison’s keloid" . [24]
Two water molecules are complexed by the manganese cluster, which then undergoes a series of four electron removals (oxidations) to replenish the reaction center of photosystem II. At the end of this cycle, free oxygen ( O 2 ) is generated and the hydrogen of the water molecules has been converted to four protons released into the thylakoid ...
Each photosystem has two main subunits: an antenna complex (a light harvesting complex or LHC) and a reaction center. The antenna complex is where light is captured, while the reaction center is where this light energy is transformed into chemical energy. At the reaction center, there are many polypeptides that are surrounded by pigment proteins.
Photosystem II (of cyanobacteria and green plants) is composed of around 20 subunits (depending on the organism) as well as other accessory, light-harvesting proteins. Each photosystem II contains at least 99 cofactors: 35 chlorophyll a, 12 beta-carotene, two pheophytin, two plastoquinone, two heme, one bicarbonate, 20 lipids, the Mn 4 CaO
Light-dependent reactions of photosynthesis at the thylakoid membrane. Light-dependent reactions are certain photochemical reactions involved in photosynthesis, the main process by which plants acquire energy. There are two light dependent reactions: the first occurs at photosystem II (PSII) and the second occurs at photosystem I (PSI).
Photosynthesis is divided into two stages—the light reactions, where water is split to produce oxygen, and the dark reactions, or Calvin cycle, which builds sugar molecules from carbon dioxide. The two phases are linked by the energy carriers adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate (NADP + ).
Caustics produced by a glass of water, visible as patches of light Cardioid caustic at the bottom of a teacup Caustics made by the surface of water Caustics in shallow water In optics , a caustic or caustic network [ 1 ] is the envelope of light rays which have been reflected or refracted by a curved surface or object, or the projection of that ...
Chlorophyll is the primary pigment in plants; it is a chlorin that absorbs blue and red wavelengths of light while reflecting a majority of green. It is the presence and relative abundance of chlorophyll that gives plants their green color. All land plants and green algae possess two forms of this pigment: chlorophyll a and chlorophyll b.