1. Photosynthesis Summary equation: Concept summary: Opposite of oxidative respiration Respiration: - energy in C-H bonds released - carbon is oxidized - electrons - after energy harvested as ATP are donated to O 2  water made

2. Photosynthesis: - Electrons – (H atoms) are taken from H 2 O - Carbon reduced (H atoms added) - Energy rich C-H bonds formed *Takes energy input to make happen  Sunlight needed!

3. Pigments Molecules that absorb wavelengths of light 1. Chlorophylls a,b,c,d 2. Carotenoids 3. Xanthophylls

4. Pigment absorption spectra

5. Photosynthesis overview

6. Light reactions –Occur on membranes Bacteria – cell membranes Plants,algae – chloroplast membranes of thylakoids

9. Summary of light reaction details 1.P 680 absorbs photon (light) 2.Excited P 680 e -  electron transport system 3.H 2 O split, restoring e - to P 680 and adds H + to thylakoid interior. O 2 gas released 4.Energy from P 680 e - powers pumping of H + into thylakoid interior

10. 5. P 700 (photosystem I) absorbs photons 6. P 700 e - replaced by P 680 e - 7. Excited P 700 e -  transport system 8. Energy from P 700 e - used to reduce NADP + to NADPH

11. InOut lightATP H 2 ONADPH + O 2 NADP +

15. The Calvin Cycle (Carbon fixation, dark reactions) Occurs in stroma of chloroplast H atoms and energy (ATP) from light reactions used to assemble C 6 H 12 O 6 from 6CO 2 Biochemical pathway cycle 6 turns of cycle  1 glucose Enzyme catalyzed – each step Enzymes have an optimum temp…implications?

18. Hot climate alternatives to Calvin (C 3 ) cycle: 1. C 4 pathway – many grasses 2. CAM pathway – stomata close by day - succulents (cacti)