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The P700 reaction center is composed of modified chlorophyll a that best absorbs light at a wavelength of 700 nm. [14] P700 receives energy from antenna molecules and uses the energy from each photon to raise an electron to a higher energy level (P700*).
Reaction centers are present in all green plants, algae, and many bacteria.A variety in light-harvesting complexes exist across the photosynthetic species. Green plants and algae have two different types of reaction centers that are part of larger supercomplexes known as P700 in Photosystem I and P680 in Photosystem II.
Photosystem I operates with the functions of producing NADPH, the reduced form of NADP + (Fd 2-red + NADH + 2 NADP + + H + = Fd ox + NAD + + 2 NADPH.), at the end of the photosynthetic reaction through electron transfer, and of providing energy to a proton pump and eventually ATP, for instance in cyclic electron transport.
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.
The reaction center initiates a complex series of chemical reactions that capture energy in the form of chemical bonds. For photosystem II, 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, pheophytin , leaving the chlorophyll a in an ...
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.
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Photosynthetic reaction centre genes from PSII (PsbA, PsbD) have been discovered within marine bacteriophage. [12] [13] [14] Though it is widely accepted dogma that arbitrary pieces of DNA can be borne by phage between hosts (transduction), one would hardly expect to find transduced DNA within a large number of viruses. Transduction is presumed ...