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Unformatted text preview: October 8, 2010 Photosynthesis and the fixation of carbon Energy from light: light eraction Fixation of carbon: dark reaction Thykaloid disks in the stroma in chloroplasts How does the topology of chloroplasts compare with that of mitochondria? Chloroplasts have an extra compartment Electron transport chains, photosynthestic light capturing systems and ATPase synthase all live on the thylakoid membranes (contrasts inner membrane) Light and dark reactions Typically sunlight- not always Carbon dark reactions dont ONLY occur in light, but do not need light, use light indirectly Expensive process of making carbs out of CO2 Light reaction Antenna complex Membrane protein complexes Chlorophylls and other pigments Photochemical vreaction center From photosynthetic bacteria Special chlorophylls in reaction Bleed of energy in discrete steps so you can use them later for all the things a cell wants to do In cyano bacteria and plants: photosystem II catalyzes First in the series (weird) coordinates the xygezn from 2 water molecules Job of proteins is to orient pigments in the system and help them interact with ETC Overciew of cynaobacteria Same as mitochondria, e- coming down the chain Harvesting light energy to make a high energy compound Higher plants can use water as donor of elections, while cyano cannot Dark reactions Carbon fixatrion has lousy enzyme Chemisomosis and the chloroplast C4 plants have 4 th carbon, only center cells in bundle sheath makes carbs Designed to function when dry/arid Close of leaves to prevent evaporation Uses back up system C3- all chloroplasts used to make carbs...
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