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Photosynthesis
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Photosynthesis

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  1. Photosynthesis

  2. Light Dependent ReactionLight Independent Reaction

  3. How is Light Energy converted into Chemical Energy (FOOD)

  4. Chloroplasts: Site of Photosynthesis

  5. Light Dependent Reaction: series of Oxidation Reduction Reactions • Reactants • Water • NADP+ • Light • PURPOSE: • Split (oxidize) the Water Molecule-removes H+ • Produce ATP for Calvin Cycle • Reduce NADP+ to NADPH-carries H+ to Calvin Cycle • Products • Oxygen • ATP • NADPH

  6. Light Dependent Reaction inside the thylakoid membrane

  7. Light Dependent Reaction

  8. Light Dependent Reaction 1.Photon of light strikes chlorophyll molecules 2.Chl loses electrons (oxidized) at the reaction center chl -> chl+ + electrons 3.Excited electrons are captured by primary receptor(-reduced) 4. Photolysis and oxidation of water molecule in thylakoid membrane H2O -> 2H+ + electrons + O (joins another O) waste product 5. Electrons from H2O reduce chl+ (chl+ + electrons -> chl) • Chemiosmosis produces ATP as electrons are moved from one receptor to another, releasing energy in the process 7. Electrons reduce chl+ in photosystem I which lost electrons when chl was ecited by photons of light 8. Primary acceptor captures electrons and passes them to NAPD+ 9. NADP+ (reduced) + electrons + H = NADPH 10. NADPH is formed in stroma where the H will be used to produce glucose

  9. Photophosphorylation produces ATP

  10. Photophosphorylation(Chemiosmosis-producing ATP) 1. H+ ions accumulate in stroma after photolysis of water 2. Electrons move along electron transport chain in thylakoid membrane-release energy to pump H+ into thylakoid • High concentration of H+ in thylakoid causes pH to drop(pH=5); pH=8 in stroma.This creates a concntration gradient from thylakoid to stroma.

  11. Chemiosmosis continued 4. H+ move along gradient through ATP synthetase (in thylakoid membrane) into the stroma • Energy released by moving H+ is captured by ADP and P to produce ATP molecules • ATP is used to power the Light Independent Reaction

  12. Non cyclic photophosphorylation • Produces ATP • Reduces NADP+ to NADPH • Involves PS I and II • P680 and P700 nm • Photolysis of water

  13. Cyclic Photophosphorylation • Produces ATP only • No photolysis of H2O • Involves PS I only • P700 nm • Evolutionary Remnant • Only photosystem in early prokaryotes-used to make ATP, not sugars

  14. Light Independent Reaction • Occurs in absence or presence of light • Carbon Fixation-conversion of an inorganic form of carbon to an organic form • Occurs in the Stroma • Also referred to as the Calvin Cycle-cyclical

  15. NEEDED Carbon Dioxide RuBP Provides energy reducing power to make Organic Compounds: carbohydrates,amino acids, etc ATP -> ADP + P NADPH ->NADP+ + H PRODUCED RuBP Triose Phosphate 6 turns of the Calvin Cycle makes 1 molecule of glucose ADP NADP+ Participants in the Light Independent Reaction