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Unformatted text preview: Process of Photosynthesis The process of photosynthesis is conveniently divided into two parts: the energy-fixing reaction (also called the light reaction) and the carbon-fixing reaction (also called the light-independent reaction, or the dark reaction). Energy-fixing reaction The energy-fixing reaction of photosynthesis begins when light is absorbed in photosystem II in the thylakoid membranes. The energy of the sunlight, captured in the P680 reaction center, activates electrons to jump out of the chlorophyll molecules in the reaction center. These electrons pass through a series of cytochromes in the nearby electron-transport system. After passing through the electron transport system, the energy-rich electrons eventually enter photosystem 1. Some of the energy of the electron is lost as the electron moves along the chain of acceptors, but a portion of the energy pumps protons across the thylakoid membrane, and this...
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- Fall '07