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:8/22/2014)... to purchase fuel cell cars from Toyota and other ... cars will run on hydrogen made from natural gas, ... Now scientists at Stanford University have developed a low-cost, ... produce hydrogen by water electrolysis. The battery sends ... water into hydrogen and oxygen gas. Unlike other water ...
(Date:8/21/2014)... BLOOMINGTON, Ind. -- A new study of American ... partner, men have the highest orgasm rates. On ... time, with their sexual orientation making little difference. ... On average, women experience orgasm 62.9 percent of ... -- and this pattern varies with women,s sexual ...
(Date:8/21/2014)... to dandruff, eczema and other itchy, flaky maladies in ... reachesincluding Hawaiian coral reefs and the extreme environments of ... in the scientific journal PLOS Pathogens considers ... the genus Malassezia in light of new ... the world. , University of Hawai,i at Mānoa scientist ...
Breaking Biology News(10 mins):Stanford scientists develop a water splitter that runs on an ordinary AAA battery 2Stanford scientists develop a water splitter that runs on an ordinary AAA battery 3Orgasm rates for single women less predictable than men's, vary by sexual orientation 2Orgasm rates for single women less predictable than men's, vary by sexual orientation 3Orgasm rates for single women less predictable than men's, vary by sexual orientation 4From dandruff to deep sea vents, an ecologically hyper-diverse fungus 2
... Athene Donald has won the Science and Technology award ... honor to Professor Donald, Glamour magazine praised her as a ... real path for herself in the male-dominated world of physics." ... Physics at the University of Cambridge in the United Kingdom ...
... CAA researcher at Charles Drew University of Medicine and Science ... a promising, natural therapy for cancer. Dr. Mamdooh Ghoneum ... on "Cell Death Mechanism," sponsored by the American Association for ... San Diego. "The central focus of the meeting ...
... RIVERSIDE, Calif. Stem cell research at the University of ... establishment of a new Stem Cell Core Facility (SCCF) ... doing stem cell research that ordinarily would not be available ... Noel Keen Hall, had its grand opening on Friday, Jan. ...
Cached Biology News:Charles Drew cancer studies with yeast yield excellent results 2UC Riverside's new state-of-the-art technology to accelerate stem cell research 2
Other biology definitionOther Tags