1. Photosynthesis

2. Last Topic= How do we burn glucose to make energy
This Topic=How do organisms make glucose

3. Photosynthesis
= Capture Sunlight energy and convert it into the chemical energy stored in glucose
+ 6H2O 12

4. What do we mean by “sunlight energy?”

5. Sunlight Light=radiation Radiation travels in waves
Frequency=number of waves in a defined time

6. Wavelengths
Visible Light Spectrum

7. Photons
Although a wave, light travels in energy bundles called PHOTONS

8. What part of a plant absorbs these photons?

9. Photosynthetic Pigments
Chlorophyll a
Absorbs red and blue, Reflects green
Chlorophyll b
Carotenes
Reflects Orange
Xanthophylls
Reflects Yellow

10. Chlorophyll Structure
More Similar or Different?

11. Purpose of Accessory Pigments
Ex. Carotenes and Xanthophylls
Capture additional wavelengths of light and pass energy onto the chlorophylls

12. Who has which pigments? Plants, green algae, euglenoids:
Chlorophyll a and b and carotenoids
Brown algae, diatoms, dinoflagellates:
Chlorophyll a and c and carotenoids
Red Algae:
Chlorophyll a, carotenoids and phycobilins

13. Brown Algae
Red Algae Tide
Green Algae

14. Absorption Spectrum

15. In the absence of sunlight which color of light bulb is best to grow plants?

16. Best: Red and Blue (Absorbed)
Worst: Green (Reflected)

17. Chloroplast Anatomy Grana= Stacks of sacs filled with Chlorophyll
= Each sac is called a thylakoid
= Reactions occur along the membranes of the thylakoids
Stroma=Gel-like material around grana

18. Reactions of Photosynthesis
Light-Dependent Reactions
Held in Grana
Need Sunlight or Red or Blue light
Light-independent reactions (a.k.a.Carbon Fixation Reactions or Calvin Cycle)
Held in Stroma
Can occur day or night

19. Light-Dependent Reactions

20. Light-Dependent Reactions

21. Light-Depdendent Reactions
Photosystem II molecules of chlorophyll absorb light and get excited.
H2O is split (Photolysis)
Electrons passed to thylakoid cytochromes in membrane for electron transport/chemiosmosis
Free H+s created
O2 waste created

22. Light Reactions 3. ATP created along ETC chain
4. Electrons from Photosystem II passed to Photosystem I chlorophyll
5. Photosystem I gets excited with absorption of light and electrons passed to 2nd ETC
6. Last receiver of electrons is NADP+ (with Hs of photolysis you get NADPH)

23. Light Reactions

25. Light-Independent Reactions (In Stroma)3
Cycles goes 6 times around to make 1 glucose

26. Overall Photosynthesis

27. Factors affecting photosynthesis
Light intensity
Temp
Water
minerals

28. C4 and CAM Plants C4 CAM Corn, Sugarcane, Tropical Grasses
On hot days they close their stomata to conserve water
Altered photosynthesis procedure
CAM
Cacti
Close stomata during day