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IMPORTANT “PLAYERS” IN PHOTOSYNTHESIS

IMPORTANT “PLAYERS” IN PHOTOSYNTHESIS. Electrons CO 2 H 2 O Sunlight (Photons). Electron Carriers (Shuttle buses) NADPH ATP, ADP, P Photosystems I & II. Where is all this happening?. The Chloroplast 2 parts-----1) Thylakoid membranes-- Stacks of thylakoids are grana

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IMPORTANT “PLAYERS” IN PHOTOSYNTHESIS

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  1. IMPORTANT “PLAYERS” IN PHOTOSYNTHESIS Electrons CO2 H2O Sunlight (Photons)

  2. Electron Carriers (Shuttle buses) • NADPH • ATP, ADP, P • Photosystems I & II

  3. 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

  4. Photosynthesis-->2 Stages • I. Light Reaction-->4 parts • II. “Dark” Reaction-->4 steps

  5. Light Reaction • 1) Light Absorption • 2) Electron Transport • 3) Oxygen Production • 4) ATP formation

  6. 1) Light Absorption • Light is absorbed by a photosystem on the thylakoid membranes

  7. (A photosystem contains clusters of chlorophyll molecules & accessory pigments)

  8. 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

  9. 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)

  10. At the end of the ETC, the high energy electrons are passed to their final destination NADP+

  11. NADP+ + H+ + 2e- --->NADPH (NADPH is our carrier molecule, it carries electrons e- and Hydrogens H+)

  12. 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

  13. 4) ATP Formation • When H2O 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.

  14. 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

  15. ATP SYNTHASE

  16. 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

  17. 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

  18. 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

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