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Like plants, the cyanobacteria use water as an electron donor for photosynthesis and therefore liberate oxygen; they also use chlorophyll as a pigment.In addition, most cyanobacteria use phycobiliproteins, water-soluble pigments which occur in the cytoplasm of the chloroplast, to capture light energy and pass it on to the chlorophylls.
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 ...
Eukaryotic photoautotrophs absorb photonic energy through the photopigment chlorophyll (a porphyrin derivative) in their endosymbiont chloroplasts, while prokaryotic photoautotrophs use chlorophylls and bacteriochlorophylls present in free-floating cytoplasmic thylakoids or, in rare cases, membrane-bound retinal derivatives such as ...
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 ...
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.
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.
The electron in the higher energy level is unstable and will quickly return to its normal lower energy level. To do this, it must release the absorbed energy. This can happen in various ways. The extra energy can be converted into molecular motion and lost as heat, or re-emitted by the electron as light (fluorescence).
All biological pigments selectively absorb certain wavelengths of light while reflecting others. [28] [29] The primary function of pigments in plants is photosynthesis, which uses the green pigment chlorophyll and several colourful pigments that absorb as much light energy as possible.