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The light-harvesting system of PSI uses multiple copies of the same transmembrane proteins used by PSII. The energy of absorbed light (in the form of delocalized, high-energy electrons) is funneled into the reaction center, where it excites special chlorophyll molecules (P700, with maximum light absorption at 700 nm) to a higher energy level.
Photoexcitation is the first step in a photochemical process where the reactant is elevated to a state of higher energy, an excited state.The first law of photochemistry, known as the Grotthuss–Draper law (for chemists Theodor Grotthuss and John W. Draper), states that light must be absorbed by a chemical substance in order for a photochemical reaction to take place.
Photodissociation, photolysis, photodecomposition, or photofragmentation is a chemical reaction in which molecules of a chemical compound are broken down by absorption of light or photons. It is defined as the interaction of one or more photons with one target molecule that dissociates into two fragments.
He showed that isolated chloroplasts give off oxygen in the presence of unnatural reducing agents like iron oxalate, ferricyanide or benzoquinone after exposure to light. In the Hill reaction: [91] 2 H 2 O + 2 A + (light, chloroplasts) → 2 AH 2 + O 2. A is the electron acceptor. Therefore, in light, the electron acceptor is reduced and oxygen ...
The various colors are made by the combination of the different layers of the chromatophores. These cells are usually located beneath the skin or scale the animals. There are two categories of colors generated by the cell – biochromes and schematochromes. Biochromes are colors chemically formed microscopic, natural pigments.
It is the antithesis of a photochemical reaction, in which light is used to drive an endothermic chemical reaction. Here, light is generated from a chemically exothermic reaction. The chemiluminescence might be also induced by an electrochemical stimulus, in this case is called electrochemiluminescence .
Color coding: yellow=sulfur; blue=nitrogen; black=carbon; red=oxygen; white=hydrogen. Luciferin (from Latin lucifer 'light-bearer') is a generic term for the light-emitting compound found in organisms that generate bioluminescence. Luciferins typically undergo an enzyme-catalyzed reaction with molecular oxygen.
Light skin is a human skin color that has a low level of eumelanin pigmentation as an adaptation to environments of low UV radiation. [ 1 ] [ 2 ] Due to migrations of people in recent centuries, light-skinned populations today are found all over the world.