The Cycles of Photophosphorylation

There are two different light reaction cycles that occur in the thylakoid membrane within the chloroplast. The first, and most complex cycle is the non-cyclic. It begins with an H20 molecule splitting into 2H+ and ½ O2 in the process of photolysis. (During photolysis oxygen is released as a byproduct.) The two electrons lost from H20 are transferred to chlorophyll 680. Different pigments in Photosystem II can absorb specific wavelengths of light. The energy …

…Photosystem I. From this photosystem electrons move to a Primary Acceptor. The Primary Acceptor then sends the electrons to a chemical, ferredoxin. From ferredoxin they move to the Cytochrome complex. Between the Cytochrome complex and plastocynin energy for chemiosmotic synthesis of ATP is released. The electrons then cycles back to Photosystem I and repeats until a feedback mechanism slows the production because the Calvin-Benson cycle has enough of both ATP and NADPH to produce glucose.