important “players” in photosynthesis electrons co 2 h 2 o sunlight (photons) electrons co 2...
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IMPORTANT “PLAYERS” IN
PHOTOSYNTHESIS
IMPORTANT “PLAYERS” IN
PHOTOSYNTHESISElectrons
CO2
H2OSunlight (Photons)
ElectronsCO2
H2OSunlight (Photons)
• Electron Carriers (Shuttle buses)
• NADPH• ATP, ADP, P• Photosystems I & II
• Electron Carriers (Shuttle buses)
• NADPH• ATP, ADP, P• Photosystems I & II
Where is all this happening?
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
Photosynthesis-->2 StagesPhotosynthesis-->2 Stages
• I. Light Reaction-->4 parts• II. “Dark” Reaction-->4 steps
• I. Light Reaction-->4 parts• II. “Dark” Reaction-->4 steps
Light ReactionLight 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
1) Light Absorption1) Light Absorption
• Light is absorbed by a photosystem on the thylakoid membranes
• Light is absorbed by a photosystem on the thylakoid membranes
• (A photosystem contains clusters of chlorophyll molecules & accessory pigments)
• (A photosystem contains clusters of chlorophyll molecules & accessory pigments)
• 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
• 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
2) Electron Transport2) 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)
• At the end of the ETC, the high energy electrons are passed to their final destination NADP+
• At the end of the ETC, the high energy electrons are passed to their final destination NADP+
NADP+ + H+ + 2e- --->NADPHNADP+ + H+ + 2e- --->NADPH
(NADPH is our carrier molecule, it carries electrons e- and Hydrogens H+)
(NADPH is our carrier molecule, it carries electrons e- and Hydrogens H+)
3) Oxygen Production3) 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
4) ATP Formation4) 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.
• 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.
• 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
The Dark Reaction (Calvin Cycle) Step 1The 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
Calvin cycle Step 2Calvin 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
Step 3 Regeneration of RUBP
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