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Published byKathryn Simmons Modified over 9 years ago
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IMPORTANT “PLAYERS” IN PHOTOSYNTHESIS Electrons CO 2 H 2 O Sunlight (Photons) Electrons CO 2 H2OH2O Sunlight (Photons)
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Electron Carriers (Shuttle buses) NADPH ATP, ADP, P Photosystems I & II Electron Carriers (Shuttle buses) NADPH ATP, ADP, P Photosystems I & II
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Where is all this happening? The Chloroplast 2 parts-----1) Thylakoid membranes- - Stacks of thylakoids are grana 2) Matrix--The soupy inside of the chloroplast The Chloroplast 2 parts-----1) Thylakoid membranes- - Stacks of thylakoids are grana 2) Matrix--The soupy inside of the chloroplast
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Photosynthesis-->2 Stages I. Light Reaction-->4 parts II. “Dark” Reaction-->4 steps I. Light Reaction-->4 parts II. “Dark” Reaction-->4 steps
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Light Reaction 1) Light Absorption 2) Electron Transport 3) Oxygen Production 4) ATP formation 1) Light Absorption 2) Electron Transport 3) Oxygen Production 4) ATP formation
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1) Light Absorption Light is absorbed by a photosystem on the thylakoid membranes
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(A photosystem contains clusters of chlorophyll molecules & accessory pigments)
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The electrons of the chlorophyll are excited by sunlight and stripped off, raising them to a higher energy level (To do work) where they are passed to electron carrier molecules
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2) Electron Transport The high energy electrons (The excited ones) are passed along a series of electron carriers (proteins in the membrane) The carriers are known as the ETC (Electron Transport Chain) The high energy electrons (The excited ones) are passed along a series of electron carriers (proteins in the membrane) The carriers are known as the ETC (Electron Transport Chain)
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At the end of the ETC, the high energy electrons are passed to their final destination NADP+
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NADP+ + H+ + 2e- --->NADPH (NADPH is our carrier molecule, it carries electrons e- and Hydrogens H+)
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3) Oxygen Production The electrons that were stripped from the chlorophyll are paid back to the original chlorophyll molecule, from the splitting of H2O. (Photolysis) 2H20---> O2 + 4H+ + 4e-s The electrons that were stripped from the chlorophyll are paid back to the original chlorophyll molecule, from the splitting of H2O. (Photolysis) 2H20---> O2 + 4H+ + 4e-s
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4) ATP Formation When H 2 O is split, the H+’s are released inside of the thylakoid membrane. As e-’s are passed from chlorophyll to NADP+, more H+’s are pumped across the membrane. The inside becomes more positively charged. When H 2 O is split, the H+’s are released inside of the thylakoid membrane. As e-’s are passed from chlorophyll to NADP+, more H+’s are pumped across the membrane. The inside becomes more positively charged.
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This Condition sets the stage for the chemiosmosis of H+ ions. (high-->low) H+ ions can pass through a special protein enzyme port (ATP Synthase) that attaches a phosphate to ADP forming ATP This Condition sets the stage for the chemiosmosis of H+ ions. (high-->low) H+ ions can pass through a special protein enzyme port (ATP Synthase) that attaches a phosphate to ADP forming ATP
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ATP SYNTHASE
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The Dark Reaction (Calvin Cycle) Step 1 3 CO2 molecules enter the cycle Each join with a 5 carbon RUBP and split-->Into 6 3 carbon PGA 3 CO2 molecules enter the cycle Each join with a 5 carbon RUBP and split-->Into 6 3 carbon PGA
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Calvin cycle Step 2 The 6 molecules of PGA change into 6 molecules of PGAL (ATP & NADPH is used for this) 1 PGAL is used to make glucose The 6 molecules of PGA change into 6 molecules of PGAL (ATP & NADPH is used for this) 1 PGAL is used to make glucose
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Step 3 Regeneration of RUBP The remaining 5 are used to make RUBP (A 5 carbon molecule) RUBP is regenerated by re- arranging the remaining 5 PGALS The remaining 5 are used to make RUBP (A 5 carbon molecule) RUBP is regenerated by re- arranging the remaining 5 PGALS
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