1. Photosynthesis Basics Where on the plant?

2. Sunlight broken up

3. Photosynthesis Basics
Not all light is equal to a plant
Pg 207
Green light is worst for photosynthesis reactions, so green light gets reflected (red and blue/violet get absorbed) and we see plants as green (especially the leaves)

4. Photosynthesis Basics
Pg 184

5. Photosynthesis Basics
Chloroplasts

6. Photosynthesis Basics
Pg 184

7. Remember: Plants do both photosynthesis and cellular respiration
Cell Respiration
The overall chemical reaction:
REACTANTS  PRODUCTS
Carbon dioxide + Water + ENERGY  Oxygen + Food
(air) (sunlight = photons) (sugars)
CO2 + H2O + Photons  O2 + C6H12O6
The “true” equations:
6CO2 + 6H2O + 2 Photons  6O2 + C6H12O6
Photosynthesis:
6O2 + C6H12O6  6CO2 + 6H2O + ATP
Cellular Respiration:
Photosynthesis is just the reverse of Cellular Respiration
Remember: Plants do both photosynthesis and cellular respiration

8. (Sugars)
Both Stages happen in the
Chloroplasts (just in different parts)

9. Stage 1: Light-Dependent Reactions
Photons (x2) H2O NADP ADP (Light energy)
empty
Light reactions:
In the thylakoid’s membranes
O NADPH ATP e-
full

10. Light Reactions
-When photons strike a molecule of chlorophyll it “excites” a single electron on the thylakoid

11. Light Reactions
-This excited e- proceeds to jump around a bit until it is funneled down to the starting point to a e- transport chain in the thylakoid membrane - this is photon reception area is called Photosystem II

12. Photosystem II (the photon first reception area) & e- transport chain
Notice: Water is broken up in the process of going from PS I to the e-chain; this is how plants make O2
Pg 211

13. A way to think of the light reactions
Pg 227

14. Webpage animations for Light reactions

15. Stage 2: Calvin Cycle (Dark reactions)
CO NADPH ATP e-
full
(x18)
Calvin Cycle:
In the Stroma
Of Chloroplast
Also known as
The “Dark Reactions”
Sugars NADP ADP
empty
Ex: Glucose
Sucrose
(x18)

16. Pg 229

17. The 2 G3P are the basic units for making sugar molecules like glucose
Calvin Cycle: See Pg 229 of textbook
Calvin Cycle requires 3 turns (with 3 CO2 total) for one G3P to be made, so with the full six turns we make 2 G3P P C C C
(x 6) O C P C C C
The used ADP and empty NADP+ that make this reaction work are recycled back to the light reactions + C P OR
Glucose
The 2 G3P are the basic units for making sugar molecules like glucose

19. Plants also store excess sugar by reorganizing it as starch.
Some is stored as starch in chloroplasts or in storage cells in roots (potato), tubers, seeds (corn), and fruits.
Heterotrophs, including humans, may completely or partially consume plants for fuel and raw materials.
On a global scale, photosynthesis is the most important process to the welfare of life on Earth.
Each year photosynthesis synthesizes 175 billion tons of carbohydrates.