February 26, 2007

February 26, 2007 - February 26, 2007 Molecular Structure...

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February 26, 2007 Molecular Structure of Chlorophyll Light is absorbed by the ring structure Hydrocarbon tail secures the molecule to the thylakoid membrane What happens when chlorophyll absorbs a photon? Fluorescence – energy is given off as heat No biological functions Energy is passed to another molecule Pigments are arranged into antenna systems Pigments are packed together Excitation energy is passed on from one molecule to another Antenna System Energy moves from higher energy to lower energy Energy ends up in the reaction center A chlorophyll: a molecule that absorbs the longest wavelengths Excited Chlorophyll Excited chlorophyll acts as a reducing agent Excited electron is less tightly held to the nucleus and is easily transferred Reduced NADP+ generating a proton-motive force that drives ATP synthesis The Light Reactions: Electron Transport and Reductions The Light Reactions The electron from chl* participates in electron transport Thylakoid membrane Sets up a proton concentration gradient across the membrane Products are NADPH + H+ and ATP NADPH is used in anabolic reactions 2 types of electron transport Noncyclic – produces NADPH + H+ and ATP Cyclic – produces only ATP Noncyclic electron transport Light energy is used to oxidize H2O forming O2, H+ and electrons Requires 2 different photosystems Photosystem I – reduction of NADP+ Rxn center absorbs light at 700nm Photosystem II - oxidation of water molecules and drives ATP synthesis
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This note was uploaded on 08/27/2008 for the course BIOL 2160 taught by Professor Harmych during the Spring '08 term at Toledo.

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February 26, 2007 - February 26, 2007 Molecular Structure...

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