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Unformatted text preview: ents in a Photosystem 2. This molecule (P700 or P680) is the Reaction P680 Reaction Center of a photosystem Center 3. Reaction center accepts energy and donates electron to acceptor molecule reaction center (a specialized chlorophyll a molecule) 5 Electron Transport System
• Adjacent to photosystem • Acceptor molecule donates electrons from reaction center • As electrons flow through system, energy they release is used to produce ATP and, in some cases, NADPH 1. Cyclic Electron Flow
– are donated by P700 in photosystem I to acceptor molecule – flow through electron transport system and back to P700 2. Electron flow drives ATP formation (only!) 3. No NADPH is formed
electron acceptor e– e– Electron transport system e– ATP
e– P700 6 2. Noncyclic Electron Flow
1. Two-step pathway for light absorption and electron excitation 2. Uses two photosystems: type I and type II 3. Produces ATP and NADPH ATP NADPH 4. Involves photolysis - splitting of water photolysis
• Water-Splitting enzyme • Provides electrons for noncyclic flow Machinery of Noncyclic Electron Flow
ATP + Pi ATP ATP synthase
H+ H+ H+ H+...
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This document was uploaded on 03/18/2010.
- Spring '09