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Unformatted text preview: Photosynthesis Photosynthesis- In simple terms: photosynthesis uses light energy (photons) to make organic compounds (sugars)- 6CO2 + 6H2O -> C6H12O6 + O2 - It is the most important set of chemical reactions in the biosphere- Revisit basic chemistry: loss and gain of electrons -> Redox reactions (revisited)- Oxidation: the loss of electrons (in biological systems; often dehydrogenation)- Reduction: the gain of electrons- Usually coupled so: thus called a redox reaction- The same molecule can be: o Oxidized by one molecule o Reduced reduced by a different molecule- Affinity for electrons controls direction of electron flow Electron carriers- Electron carriers: molecules that can be reversibly oxidized and reduced o Can accept and donate e - Wary in their affinity for electron o Arrange by increasing affinity for electrons: electron transport chain (series of oxidatinon/reduction) o Gradual release of energy that can be captured- Allows maximal synthesis of ATP What does this have to do with photosynthesis?- We are going to oxidize H2O toOc, and HT^+ during part of phtosynteuos- We are going to reduce CO2 to glucose during part of photosynthesis (also endergonic) 6CO2+ 6H2-> 62H12O6 + 6O2- Endergonic energy input: the sun! Site of photosynthesis (figure 8.1) - Occurs within cells, usually in the leaf- Organelle involved is the chloroplast- Structure of choloroplast is important o Thylakoid membranes: Create enclosed compartment within disks o Must be intact for photosynthesis to occur Must maintain H+ concentration gradient Two parts to photosynthesis: light reactions- Light reactions (occur in thylakoid) o Requires light as energy as source o Oxidize H2Oproduce ATP & NADPH (reducing power) NADPH able to reduce other molecules by donating...
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This note was uploaded on 10/24/2011 for the course BIOL 110 taught by Professor Mason during the Fall '07 term at Purdue University-West Lafayette.
- Fall '07