Photosynthesis Chapter 7 Photosynthesis Solar energy to carbohydrate Carbs from photosynthesis used by every living thing on earth Producers Plants Algae Cyanobacteria Consumers Plants All green portions of plants Leaves Surface area Mesophyll section is photosynthetic section Plants Chlorophyll captures solar energy Water roots Carbon dioxide stomata All materials to chloroplasts Chloroplasts Double membrane Stroma fluid with enzymes Reduces carbon dioxide Thylakoids sacs Captures solar energy chlorophyll Granum stacks Thylakoid spaces are connected Chloroplasts Thylakoids capture solar energy that drives rxn Rxn occurs in stroma Carbon dioxide carbohydrate Produces enough to provide energy for plant and others Photosynthesis Pigments absorb portions of the visible light spectrum Chlorophyll a Chlorophyll b Carotenoids Photosynthesis the reaction Solar energy CO2 2H2O CH2O Solar energy 6CO2 6H2O C6H12O6 H2O O2 6O2 Photosynthesis the reaction Redox rxn CO2 CH2O reduction H2O O2 oxidation Photosynthesis the reaction Light reactions Thylakoid membrane Absorbs solar energy Energizes electrons Electron transport system Calvin cycle reaction Stroma CO2 reduced Light reactions Noncyclic electron pathway Electrons flow from water to NADPH Nicotinamide adenine dinucleotide phosphate Photosystems Pigment complex Pigments electron acceptors Photosystem II Photosystem I Light reactions PS II Pigments antennae Chlorophyll b Carotenoids Chlorophyll a reaction center Increased energy when electron arrives at rc Electron from oxidation of water Light reactions PS II Water split by enzymes Enzyme connected to rc Releases electrons one at a time Oxygen released to atmosphere 2H stay in thylakoid space Light reactions PS II Electron transport system Receptor molecules Pass e from molecule to molecule Quinone Proton pump complex Plastocyanin protein PS I Pumps proton into thylakoid space for ATP synthesis Light reactions ATP chemiosmosis Protons from water and proton pump from stroma in thylakoid space Thylakoid membrane impermeable to protons Pumped across membrane by ATP synthase What kind of molecule is ATP synthase As it proton passes through ADP in stroma is phosphorylated ATP Light reactions PS I Complex 13 protein subunits center 130 chlorophyll a antenna E Passed to more acceptors To NADP Accepts 2 e and one H NADP reductase NADPH Light reactions Cyclic reactions From PS I to PS I Produces more ATP Electron shuttled to proton pump Does not make NADPH Plants need more ATP than NADPH Depends of need Calvin cycle Energy from ATP from light rxns Reduction possible from NADPH Carbon fixation Carbon dioxide reduction Regeneration of RuBP Ribulose 1 5 bisphosphate Calvin cycle Carbon dioxide fixation CO2 RuBP five carbon molecule 6 carbon molecule 2 three C molecules Phosphoglycerate PGA Enzyme RuBP carboxylase rubisco Slow 50 of protein in most plants Most abundant protein on earth Calvin cycle Reduction of carbon dioxide Each PGA reduced to PGAL G3P NADPH donates electrons ATP provides energy R CO2 R CH2O carb Enzymes PGA kinase G3P dehydrogenase Calvin cycle Regeneration of RuBP Takes three turns of cycle for one PGAL G3P For every 1 released 5 go to the regeneration of to be released 3 RuBP Also costs ATP 5 PGAL 3 RuBP Released PGAL G3P used for many things Calvin cycle Overall reaction 3CO2 9ATP 6NADPH water G3P glyceraldehyde 3 phosphate 8P 9ADP 6NADP Calvin cycle PGAL G3P Glucose Sucrose Starch cellulose Fatty acids glycerol Amino acids
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