BIOL 111 301 1st Edition Lecture 11 Outline of Last Lecture I Review quiz II Glycolysis III Junction Reactions IV Overview of the citric acid cycle V Mitochondrial structure VI VII Oxidative phosphorylation How much energy ATP was harvest4ed from glucose Outline of Current Lecture I Review Preview II Nature Of Light III Pigments IV What happens to the absorbed light V Light Reactions converting solar energy to chemical energy VI How much energy did we harvest from the sun Current Lecture Review Preview o Energy Matter o Redox rxns o Laws of Thermodynamics o Kinetic vs Potential energy o Follow carbons o Follow electrons o Carbon cycle o Electron transport chain chemiosmosis o ATP synthase Nature Of Light o Form of energy on electromagnetic spectrum from 380 750 nm o Both particle and wave properties o Wavelength distance between crests o Energy of light 1 wavelength so more E from shorter wave o Photon discrete light particles Pigments o Substances that selectively absorb visible light o Chlorophyll a o Chlorophyll b o Carotenoids What happens to the absorbed light o Photon hits pigment e excited then falls Fig 2 8 o Dissipation Fig 10 11 Emit photon of light Fluorescence Emit heat Transfer e to other pigment Resonance transfer Light Reactions converting solar energy to chemical energy o 1 Light harvesting complexes PSII and PSI Within thylakoid membrane Contain proteins and few 100 pigments Outer pigments absorb purple wavelengths inner absorb red Excited e energy transferred via resonance transfer from high E low E o 2 Linear electron flow produces ATP and NADPH Photons excite e in pigments and energy transferred to pair of chlorophyll a P680 donates e to a primary acceptor in the reaction complex P680 strongest oxidizing agent in the world Rips 2 e from WATER NOT light Water donates 2 e to excited P680 one by one Photons excite e in pigments and energy transferred to P680 Water donates 2 e to excited P680 one by one E fall down e transport chain via redox rxns to PSI e acceptor P700 Additional photons excite these e Photons excite e in pigments and energy transferred to P680 Water donates 2 e to excited P680 one by one E fall down e transport chain via redox rxns to PSI e acceptor P700 Additional photons excite these eo 3 Cyclic electron flow Produces ONLY ATP Use PSI Fd cytochrome complex Creates proton gradient ATP synthase How much energy did we harvest from the sun o In Linear E Transport 4 photons will Oxidize 1 H2O O2 2H 2e Transport 2 e from H2O NADP Reduce NADP NADPH to Calvin cycle Generate H in thylakoid space 2 H from H2O 4 H pumped by e transport Produce 1 5 ATP 4H ATP
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