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These pigments enter a high-energy state upon absorbing a photon which they can release in the form of chemical energy. This can occur via light-driven pumping of ions across a biological membrane (e.g. in the case of the proton pump bacteriorhodopsin ) or via excitation and transfer of electrons released by photolysis (e.g. in the photosystems ...
Each pigment absorbs light more efficiently in a different part of the electromagnetic spectrum. Chlorophyll a absorbs well in the ranges of 400–450 nm and at 650–700 nm; chlorophyll b at 450–500 nm and at 600–650 nm. Xanthophyll absorbs well at 400–530 nm.
Photosynthesis is a process where light is absorbed or harvested by pigment protein complexes which are able to turn sunlight into energy. [5] Absorption of a photon by a molecule takes place when pigment protein complexes harvest sunlight leading to electronic excitation delivered to the reaction centre where the process of charge separation can take place.
All biological pigments selectively absorb certain wavelengths of light while reflecting others. [4] [5] The principal pigments responsible are: 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 ...
Each antenna complex has between 250 and 400 pigment molecules and the energy they absorb is shuttled by resonance energy transfer to a specialized chlorophyll-protein complex known as the reaction center of each photosystem. [1] The reaction center initiates a complex series of chemical reactions that capture energy in the form of chemical bonds.
The pigments which absorb light at the highest energy level are found furthest from the reaction center. On the other hand, the pigments with the lowest energy level are more closely associated with the reaction center. Energy will be efficiently transferred from the outer part of the antenna complex to the inner part.
Due to the presence of chlorophyll a, as opposed to bacteriochlorophyll, Photosystem II absorbs light at a shorter wavelength. The pair of chlorophyll molecules at the reaction center are often referred to as P680. [1] When the photon has been absorbed, the resulting high-energy electron is transferred to a nearby pheophytin molecule.
When either of the two chlorophyll a molecules at the reaction center absorb energy, an electron is excited and transferred to an electron-acceptor molecule. Photosystem I contains a pair of chlorophyll a molecules, designated P700 , at its reaction center that maximally absorbs 700 nm light.