ch10 - Chapter 10 Photosynthesis Autotrophs =Producers...

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Chapter 10: Photosynthesis 1 Chapter 10: Photosynthesis Autotrophs =Producers Heterotrophs = Consumers Site of Photosynthesis in plans is the chloroplast/All green parts of plants, but laves are the major part. Where in leaves? In mesophyll: the interior o leaf A mesophyll usually contains 30-40 chloroplasts Half a millions per mm 2 . What is stomata? Opening on the leaf for passage of O2 and CO2 Photosynthesis requires water which is absorbed by roots and sent to other parts of the plant via veins Sugar is one of the products of photosynthesis: transported to other part via veins . Structure: Three membranes: Outer, inner and thylokoid membrane. Stroma is the dense fluid within the chloroplast Chlorophyll resides in thylokoid membrane 6CO2 + 12 H2O --------- Æ C6H12O6 + 6O2 + 6 H2O or 6CO2 + 6 H2O -------- Æ C6H12O6 + 6O2 (reverse of cellular respiration) In general: CO2 + H2O ------ Æ CH2O + O2 Where the O2 come from? From splitting H2O( NOT the CO2). Evidence: Bacteria that use H2S instead of H2O for photosynthesis, produce S not O2 as their by product. CO2 + 2 H2S ----- Æ CH2O + H2O + 2S Even though they use CO2 and produce sugar, O2 is not produced. Cellular respiration is an exergonic REDOX process: Energy is released from oxidation of sugar. a. Electrons associated with sugar’s hydrogen lose potential energy as carrier molecules transport them to oxygen forming water. b. Electronegative oxygen pulls electrons down the electron transport chain, and the potential energy released is used by mitochondrion to produce ATP Photosynthesis is an endergonic REDOX process:
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Chapter 10: Photosynthesis 2 Energy is required to reduce CO2. 1. Light is the energy source that boosts potential energy of electrons as they moved from water to sugar. 2. When water is split, electrons are transferred from the water to CO2, reducing it to sugar. Photosynthesis has two stages: 1. Light reaction : Converts light energy to chemical energy (stored in ATP and NADPH).Occurs in thylokoid membrane of chloroplast. Light energy splits water molecules and two energized electrons along with one proton (H + ) is transferred to NADP+, reducing it to NADPH. This is the source of energized electrons. Give off O2 as a by-product of splitting water. Generate ATP: The light reaction powers the addition of a phosphate group to ADP and Pi in a process called: photophosphorylation 2 Calvin cycle: a. Fixation of atmospheric CO2 and reducing it to sugar. Named after Melvin Calvin. It takes place in stroma. b. CO2 is incorporated into an existing organic molecule (carbon fixation). c.
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This note was uploaded on 11/29/2010 for the course BUSSINESS 221242 taught by Professor Michaeldouglas during the Spring '10 term at Georgia Perimeter.

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ch10 - Chapter 10 Photosynthesis Autotrophs =Producers...

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