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Download PHOTOSYNTHESIS 6CO2 + 12H2O + light → C6H12O6 + 6O2 +
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AP BIOLOGY CELLULAR ENERGETICS ACTIVITY #4 NAME_____________________ DATE___________HOUR_____ PHOTOSYNTHESIS SUMMARY E QUATION 6CO2 + 12H2O + light à C6H12O6 + 6O2 + 6H2O 6CO2 + 6H2O + light à C6H12O6 + 6O2 CO2 + H2O + light à CH2O + O2 (emphasizes production of glucose 1 carbon at a time) SITE OF P HOTOSYNTHESIS -- PLANTS Cellular Energetics Activity #4 page 1 SITE OF P HOTOSYNTHESIS – PROKARYOTES Lack chloroplasts Chlorophyll built into plasma membrane STRUCTURE OF CHLOROPLASTS Cellular Energetics Activity #4 page 2 OVERVIEW OF PHOTOSYNTHESIS CO2 Light ADP + P Light Rxns (thylakoids) ATP NADP+ Calvin Cycle (stroma) NADPH H2O O2 Light Rxns • Take e- from H2O • Use light energy to boost e- to higher energy level • Use some energy to make ATP • Add high energy eto NADP+ Cellular Energetics Activity #4 page 3 Calvin Cycle • AKA Dark Rxn • Uses ATP produced in light rxn • Takes high energy efrom NADPH and adds them to CO2 • Produces sugar 1 carbon at a time CH2O LIGHT REACTIONS – C YCLIC E LECTRON F LOW 1o electron acceptor 2e- Fd Pq H+ gradient chemiosmosis Cytochrome complex P700 Rxn Center ATP Pc Photosystem Few 100 pigment molecules (chlorophyll a, b, & carotenoids) Reaction center Chlorophyll a molecule Bound to specific proteins Closer to 1 o electron acceptor Antenna pigments absorb photons and pass to rxn center Cellular Energetics Activity #4 page 4 LIGHT REACTIONS – NONCYCLIC E LECTRON FLOW Uses downward slide of e- to create H+ conc. gradient; H+ gradient used to make ATP 1o eacceptor 1o eacceptor Fd 2e- Pq NADP+ reductase Adds 2eand H+ to NADP+ 2eCytochrome Complex Pc H2O 2e2H+ + ½O2 NADP+ P680 photosystem II Cellular Energetics Activity #4 page 5 P700 photosystem I NADPH C ALVIN C YCLE Location = Stroma RuBP = ribulose biphosphate Rubisco = RuBP carboxylase PGA = phosphoglycerate DPGA = diphosphoglycerate PGAL = phosphoglyceraldehyde glyceraldehydes phosphate RuP = ribulose phosphate Cellular Energetics Activity #4 page 7 PROBLEM – P HOTORESPIRATION If [O2] > [CO2] in leaves Rubisco fixes O2 instead of CO2 5-C compound produced 5-C à 1 PGA enters Calvin Cycle 1 glycolate (2-C) exits chloroplasts and enters peroxisomes Decreases productivity Fostered by hot, dry, bright days C4 PLANTS • Fix CO2 as 4C compound • Segregate CO2 fixation from Calvin cycle • Acts as CO2 pump • PEP carboxylase has lower affinity for O2 than rubisco • Adaptation in hot regions with intense light Cellular Energetics Activity #4 page 8 CAM PLANTS Crassulacean Acid Metabolism Cellular Energetics Activity #4 page 9
