Photosystem II

Photosystem II is a specialized protein complex that uses light energy to oxidize water, resulting in the release of molecular oxygen into the atmosphere, and to reduce plastoquinone, which is released into the hydrophobic core of the photosynthetic membrane. All oxygenic photosynthetic organisms, which include plants, algae and some bacteria, depend on photosystem II to extract electrons from water that are eventually used to reduce carbon dioxide in the carbon reduction cycle. The complex is composed of a central reaction centre in which electron transport occurs, and a peripheral antenna system which contains chlorophyll and other pigment molecules that absorb light.