Navigation Links
Photosystem


In the process of photosynthesis, light is absorbed by a photosystem (ancient Greek: phos = light and systema = assembly) to begin an energy-producing reaction. The photosytems are contained within the chloroplasts in the leaves of plants. Two types of photosystems exist: photosystem I (P700) and photosystem II (P680). Each photosystem is differentiated by the wavelength of light to which it is most reactive (700 and 680 nanometers, respectively), and the type of terminal electron acceptor. Type I photosystems use ferredoxin like iron-sulfur cluster proteins as terminal electron acceptors, while type II photosystems ultimately shuffle electrons to a quinone terminal electron acceptor.

Structure

A photosystem is made up of a reaction center pigment of chlorophyll a and numerous antenna pigments and proteins. Because chlorophyll a can only absorb light of a narrow wavelength, it works with the antenna pigments to gain energy from a larger part of the spectrum. The pigments absorb light of various wavelengths and pass along their gained energy to the reaction center chlorophyll. When the energy reaches the chlorophyll a, it releases two electrons into an electron transport chain.

Though chlorophyll a normally has an optimal absorption wavelength of 660 nanometers, it associates with different proteins in each type of photosytem to slightly shift its optimal wavelength, producing two distinct photosystem types. Other proteins serve to support the structure and electron pathways in the photosystem.

See also

External links


'"/>


(Date:2/5/2016)... 5, 2016 http://www.researchandmarkets.com/research/5kvw8m/global_facial ... "Global Facial Recognition Market 2016-2020" ... http://www.researchandmarkets.com/research/5kvw8m/global_facial ) has announced the addition of ... report to their offering. --> ... has announced the addition of the ...
(Date:2/3/2016)... -- --> --> ... Identification System Market by Component (Hardware and Software), Search ... Government, Healthcare, and Transportation) and Geography - Global Forecast ... to be worth USD 8.49 Billion by 2020 at ... The transformation and technology evolution from the manual process ...
(Date:2/2/2016)... YORK , Feb. 2, 2016 /PRNewswire/ ... facilities are primarily focused on medical screening ... measure point-of-care parameters. Wearable devices that facilitate ... user,s freedom of movement are being bolstered ... for human biomedical signal acquisition coupled with ...
Breaking Biology News(10 mins):
Other biology definition