1. 8-3 The Reactions of Photosynthesis

2. Inside a chloroplast
thylakoids: saclike membranes found in chloroplasts
arranged in stacks known as grana
contain photosystems that capture sunlight (light-dependent reactions)
stroma: gel-like matrix surrounding the thylakoids
region where the Calvin cycle takes place

3. NADPH
electron carrier that can accept and transfer a pair of high-energy electrons to another molecule

4. Light Dependent Reactions
reactions that occur in the thylakoids that produce O2 gas and convert ADP and NADP+ into energy carriers ATP and NADPH

6. B. Electron Transport Chain
A. Photosystem 2 (II)
light is absorbed by chlorophyll and energy transferred to electrons
electrons transferred to electron transport chain
water molecules broken up by enzymes into electrons, H+, and O2
B. Electron Transport Chain
electrons move through electron transport chain to photosystem 1 (I)
molecules in electron transport chain use energy to transport H+ from stroma into inner thylakoid

7. C. Photosystem 1 (I)
pigments absorb energy which is passed to electrons
electrons used to form NADPH from NADP+
D. Hydrogen Ion Movement
inner thylakoid membrane fills up with H+
outside of membrane “+” charged and inside of membrane “-” charged

8. E. ATP Formation
H+ pass through ATP synthetase to convert ADP to ATP

10. 8-3 The Reactions of Photosynthesis (part 2)

11. The Calvin Cycle
dark reactions occurring in the stroma that uses ATP and NADPH to produce high energy sugars

12. CO2 Enters the Cycle Energy Input 5-Carbon Molecules Regenerated
6-Carbon Sugar
Produced
Sugars and other compounds

13. CO2 Enters the Cycle
6 CO2 molecules are combined with six 5-carbon compounds to produce twelve 3-carbon compounds
Energy Input
energy from ATP and high-energy electrons from NADPH are used to convert the twelve 3-carbon compounds into higher energy forms

14. 6-Carbon Sugars Produced
two 3-carbon compounds are used to make a 6-carbon sugar
5-Carbon Molecules Regenerated
the 10 remaining 3-carbon compounds are converted into six 5-carbon compounds which are used to fuel the next cycle

15. CO2 Enters the Cycle Energy Input 5-Carbon Molecules Regenerated
6-Carbon Sugar
Produced
Sugars and other compounds

16. Photosynthesis Review
includes
Light-
dependent
reactions
Calvin cycle
takes place in
uses
use
take place in
Thylakoid
membranes
Stroma
NADPH
ATP
Energy from
sunlight
to produce of
to produce
ATP
NADPH O2
Chloroplasts
High-energy
sugars

17. Factors Effecting the Rate of photosynthesis
What a plant needs for maximum photosynthesis

18. water Plants need water for the light reaction
Shortage slows photosynthesis
Plants have adaptations that conserve water

19. CO2 and O2 Plants need high levels of carbon dioxide
Plants need lower levels of oxygen
If oxygen builds up in the leaf the plant undergoes photorespiration
Plant may die
Some plants store CO2 to prevent this

21. light As light increases so does photosynthesis But only to a point
Plants can only absorb so much light…called saturation point
The rate then levels off

22. Saturation point

23. temperature
Photosynthesis takes place between 0 and 35 degrees Celsius
The enzymes do not work below or above this range

25. Factors Affecting Photosynthesis
water
shortage slows or stops photosynthesis
temperature
photosynthesis depends on enzymes that function best between 0ºC and 35ºC
light intensity
increases photosynthesis until maximum rate reached for plant