Photosynthetic oxygen evolution is the fundamental process by which oxygen is generated in earth's biosphere. The reaction is part of the light-dependent reactions of photosynthesis in cyanobacteria and the chloroplasts of green algae and plants. It utilizes the energy of light to split a water molecule into its protons and electrons for photosynthesis. Free oxygen, generated as a by-product of this reaction, is released into the atmosphere.
Source : Wikipedia
The reaction 2H2O ⟶ 4e− + 4H+ + O2 is responsible for the continuation of all aerobic (i.e. oxygen breathing) life on Earth.
The production of oxygen from plants was first noted in the late 18th century, and has been very extensively studied since then. It's known that the oxygen (which originates from the plant's internal water) is generated in the plant's Oxygen Evolving Complex (OEC), using the so-called 'PS II' system. It involves the transfer of electrons (possibly one at a time), facilitated by a set of proteins.
A widely accepted theory from the 1970's (the Joliot and Kok cycle) proposes that the OECs have five 'states' and that manganese and calcium ions are essential to the process.
The process is extremely complex and has not yet been fully described - and the PS II atomic structure is not known.
Further reading : Florida State University, James Johnson.
Also see :and
Ideas for new topics, and suggested additions / corrections for old ones, are always welcome.
If you have skills or interests in a particular field, and have suggestions for Wikenigma, get in touch !
Or, if you'd like to become a regular contributor . . . request a login password. Registered users can edit the entire content of the site, and also create new pages.
( The 'Notes for contributors' section in the main menu has further information and guidelines etc.)
You are currently viewing an auto-translated version of Wikenigma
Please be aware that no automatic translation engines are 100% accurate, and so the auto-translated content will very probably feature errors and omissions.
Nevertheless, Wikenigma hopes that the translated content will help to attract a wider global audience.