Noncyclic electron flow,
the predominant route, produces both ATP and NADPH.
Photosystem II absorbs a photon of light. One of the electrons of P680 is excited to a
higher energy state.
This electron is captured by the primary electron acceptor, leaving the reaction center
oxidized.
An enzyme extracts electrons from water and supplies them to the oxidized reaction
center. This reaction splits water into two hydrogen ions and an oxygen atom that
combines with another oxygen atom to form O2.
Photoexcited electrons pass along an electron transport chain before ending up at an
oxidized photosystem I reaction center.
As these electrons “fall” to a lower energy level, their energy is harnessed to produce
ATP.
Meanwhile, light energy has excited an electron of PS I’s P700 reaction center. The
photoexcited electron was captured by PS I’s primary electron acceptor, creating an
electron “hole” in P700. This hole is filled by an electron that reaches the bottom of the
electron transport chain from PS II.
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- Fall '10
- Orlando,Rebecca
- Biology, DNA, Electron Transport Chain, Photosynthesis, Adenosine triphosphate, primary electron acceptor, noncyclic electron flow
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