1. How Photosynthesis Works

2. Base Race Photosynthesis Light Reaction Chlorophyll Calvin Cycle
Thylakoid membrane
Light Energy
H+ ions
Chemical Energy
Electron Transport Chain
Light Reaction
Calvin Cycle
Chloroplast
Stroma
NADPH
Electrons
ATP

3. Chemical formula for photosynthesis
6CO2 + 6H2O + light C6H12O6 + 6O2
chlorophyll
Carbon dioxide
enzymes
Water
Energy
Carbohydrate
(glucose)
Oxygen

4. Three stages of Photosynthesis
Energy is captured from sunlight
2. Light energy is converted to ATP and NADPH (chemical energy)
3. ATP and NADPH provide energy for the synthesis or organic compounds (glucose)

5. Chloroplast Structure
Thylakoid: houses pigments
Grana: stacks of thylakoids
Stroma: liquid between grana
Grana

6. Stage 1– Energy captured from sunlight
It is the pigments in the thylakoids that absorb the light energy from the sun
Two common pigments include:
Chlorophyll reflects green light
Carotenoids  reflect yellow and orange light
Q: Why are broccoli green and carrots orange?
A: Broccoli uses chlorophyll and carrots use carontenoids

7. Stage 2—Light Energy Chemical Energy
“Light Reactions”
These reactions take place in the thylakoids.
Q: What do the thylakoids house that make them good candidates for the light reactions of photosynthesis?
A: Pigments that absorb light energy like chlorophyll

8. Energy from the sun is absorbed and electrons are excited
2. Water is split into hydrogen and oxygen
The oxygen is released
3. Electrons move through the “electron transport chain”
ATP and NADPH are released

9. Stage Three– Chemical Energy Organic Compounds
“Calvin Cycle” or dark reactions, light independent reactions
Take place in the stroma of the chloroplast.

10. Carbon Fixation takes place
Carbon from carbon dioxide is converted into carbohydrates (glucose)
2. Requires ATP and NADPH from light reactions

11. References
/Bio%20101%20Lectures/Photosynthesis/photosyn.htm