1. Photosynthesis
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Packet #16
Chapter #8

2. Introduction I Photosynthesis Photo--”light”
The process of storing light energy from the sun in the form of glucose
The process of making sugar (glucose) using light energy
Photo--”light”
Synthesis--”make” ; “put together”
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3. Introduction II
Photosynthesis nourishes almost all of the living world directly or indirectly
Autotroph
Organism that obtains organic food molecules without eating other organisms.
Use energy from the sun or from oxidation of inorganic substances to make organic molecules from inorganic ones.
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4. Introduction III Heterotroph
An organism that obtains organic food molecules by eating other organisms or their by-products
Humans eating plant or animal matter
Fungi on feces, carcasses
Bacteria of the large intestines
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5. Photosynthesis Chemical Reaction
6CO2 + 12H2O + Light Energy --> C6H12O6 + 6O2 + 6H2O
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6. Structure of the Leaf Site of Photosynthesis
Chloroplasts are the sites of photosynthesis in plants.
Found within mesophyll cells.
Chloroplasts contain chlorophyll
A green pigment that captures light energy during photosynthesis
Found in the cells of the mesophyll of the leaves
Stomata
Pores under the leaves where CO2 enters and O2 leaves the plant/leaf
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7. Events of Photosynthesis
The Light Reactions
Photo part of photosynthesis
Calvin Cycle
Synthesis part
What does the plant synthesize?
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8. Light Reactions
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9. Light Reactions “Photo” part of photosynthesis
Convert solar energy to chemical energy
Contains the photo systems that cooperate in the light reactions of photosynthesis
Each photosystem will absorb specific wavelengths of light
Photosystem I--700nm
Photosystem II--680 nm
Oxygen is formed in photosystem II
H2O is a reactant in the formation of O2
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10. ATP & NADPH ATP is produced at Electron Transport Chain #1
NADPH is produced at Electron Transport Chain #2
ALL ATP and NADPH produced during the Light Reactions are transported to the Calvin Cycle to be used in the synthesis of glucose
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11. Light Reactions I Overall
Inputs
Light
NADP+
ADP P
H2O
Outputs
ATP
NADPH O2
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12. Cyclic vs. Non Cyclic Electron Flow
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13. Light Reactions—Non-cyclic Electron Flow
Photosystem II
The reaction center drives an oxidation-reduction reaction (Redox Reaction) that helps in the formation of oxygen.
Electron Transport Chain I
ATP produced will be used in the Calvin Cycle
Photosystem I
Continues the movement of electrons
Electron Transport Chain II
NADPH produced will be used in the Calvin Cycle
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14. Non-Cyclic Electron Flow
Uses both photosystems
Produces NADPH, ATP and oxygen
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15. Cyclic Electron Flow
Only uses photosystem I and part of Electron Transport Chain I
Produces ATP but no NADPH or O2
Used to “make-up” the necessary amount of ATP’s for the Calvin Cycle
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16. Calvin Cycle—The Dark Reactions
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17. Calvin Cycle “Dark Reactions”
Synthesis of photosynthesis
Makes sugar
Uses ATP and NADPH to convert CO2 to sugar
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18. Calvin Cycle Overall Inputs Outputs CO2 H2O ATP NADPH Sugars (Glucose)
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19. Calvin Cycle Sequence of Events
Carbon Fixation
Use of carbon dioxide
Reduction
1, 3 bisphosphoglycerate is reduced to the sugar G3P
6 ATP’s is used
Reduced using the electrons produced by the oxidation of NADPH
Regeneration of CO2 Acceptor
This acceptor, RuBP, is then re- used in carbon fixation to continue the next cycle of the Calvin Cycle
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20. Review
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