BIOL 3510 1st Edition Lecture 15 Outline of Last Lecture I Parts of the Mitochondria II Types of Electron Carriers III Oxidation Outline of Current Lecture I Parts of the Chloroplast II Photosystems III Charge Separation IV Noncyclic Photophosphorylation V Carbon Fixation in the Stroma VI Uses of Glyceraldehyde 3 phophate Current Lecture Chloroplasts contain light capturing pigments called chlorophylls and perform photosynthesis Photosynthesis creates organic molecules from CO2 using energy derived from light Parts of the Chloroplast Outer membrane highly permeable Intermembrane space composition similar to the cytosol Inner membrane less permable Stroma space enclosed by the inner membrane contains metabolic enzymes chloroplast genomes and ribosomes Thylakoid third membrane contains photosystems ETC and ATP synthase and the space it encloses The outer membrane intermembrane space and the inner membrane are part of the chloroplast envelope Chloroplast genomes are larger than mitochondrial genomes The equation for photosynthesis is light CO2 H2O sugars O2 heat Interaction with photons of light energy raises the energy of chlorophyll electrons Chlorophyll associates with proteins in photosystems in the thylakoid membrane These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Photosystems have two parts Antenna complex chlorophyll molecules capture light energy in high energy e and funnels the energy to a reaction center Reaction center contains a special pair of chlorophyll molecules that accepts energy from the atenna complex and transfers one high energy e to an e acceptor Charge Separation 1 The special pair donates an e to an electron carrier and it enters the e transport chain 2 The special pair accepts an e from a nearby donor Noncyclic Photophosphorylation The special pair in photosystem II donates e to an e transport chain o Lost e replaces by the splitting of water The special pair in photosystem I donates e to an e transport chain o Lost e is replaced by the e donated by photosystem II E are added to NADP by ferrodoxin NADP reductase to make NADPH Electron flow generates an H gradient which is used to make ATP and NADPH H2O is the source of electrons moving through the chloroplast electron transport chain ATP synthase generates ATP using energy derived from the flow of H down its electrochemical gradient into the stroma Chloroplasts can generate ATP only Cyclic phosphorylation electrons from photosystem I are transferred to the cytochrome b6 f complex instead of NADP Carbon Fixation in the Stroma ATP and NADPH generated by the light reactions are used to convert CO2 into sugar Addition of CO2 to ribulose 1 5 biphosphate is catalyzed by rubisco The net gain of the carbon fixation cycle is 1 moleculee of glyceraldehydes 3 phosphate Uses of glyceradehyde 3 phosphate 1 Converted to starch in the stroma energy storage for later 2 Transported to the cytoplasm and converted to other metabolites including sucrose energy transport 3 Transported to the cytoplasm and converted to pyruvate via glycolysis energy consumption Pyruvate enters the citric acid cycle in the plant mito Endosymbiont hypothesis origin of mitochondria and origin of chloroplasts
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