GENERAL BOTANY Lecture 9

GENERAL BOTANY Lecture 9 - B. Two options for electron...

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GENERAL BOTANY Lecture 9 - Photosynthesis I. Photosynthesis - The process that occurs in the chloroplasts of green plants in which simple sugars are formed from carbon dioxide and water in the presence of light and chlorophyll. A. Two major parts of photosynthesis 1. Light reactions a) Conversion of light energy into ATP and NADPH 2. Dark reactions a) B. Purpose of photosynthesis 1. Main biosynthetic pathway by which carbon and energy enter the web of life II. Where it occurs A. Chloroplast 1. Light reactions - granum (several thylakoids) and thylakoid membranes 2. Dark reactions - stroma III. Light reactions A. Light-trapping molecule 1. Chlorophyll (antenna chlorophyll pick up light) a) Transmits green and absorbs red and blue, etc. b) Right wavelength of energy excites an electron of chlorophyll c) Inductive resonance carries excitation energy from molecule to molecule d) Energy (P700 or P680) is transferred to an acceptor molecule
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Unformatted text preview: B. Two options for electron excitation energy 1. Cyclic (short) pathway) 2. Non-cyclic (long pathway) C. Cyclic photophosphorylation 1. (Photosystem I) LIGHT - P700 - P700* (Chl a/b redox) - [ETS: Fe-S protein-Ferredoxin-Plastoquinone] - P700 + ATP D. Non-cyclic photophosphorylation (Photosystem II and then I) 1. (Photosystem II) LIGHT - (OEC) - P680 - P680* (Pheophytin a) - [ETS: Plastoquinone- Plastocyanin + ATP - (Photosystem I) W/LIGHT - P700 - P700* (Chl a/b redox) - [ETS: Fe-S protein-Ferredoxin] - NADPH (NADPH from 2 e-and 1 H + ) 2. Electrons replaced by water (O 2 is released and H + goes into thylakoid) 3. Split of water referred to as photolysis 4. ATP comes from proton gradient (H + stored in thylakoid leaves to makes ATP) E. Use of products from photosynthesis 1. ATP - energy 2. NADPH - reducing equivalents for organic synthesis...
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This note was uploaded on 01/30/2012 for the course BSC BSC1085 taught by Professor Sharonsimpson during the Fall '10 term at Broward College.

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