1. Monday’s Topics 1.Overview of photosynthesis 2.Key early photosynthesis experiments 3. Photosynthesis: light reactions

2. From which molecule does the O2 released by plants come from? What happens to H20 during photosynthesis? (more than one answer might be correct) a. Oxidized b. Reduced c. Activated d. Looses electrons e. Gains electrons Which are the energy rich compounds generated during the light reactions?

3. Today’s Topics 1.Electron transfer during the light reactions 2.Regulation of photosynthesis 3.Evolution of photosynthetic systems

4. Energy H20H20 2 H + + ½ O 2 The Electron Transfer Process

5. Oxidized State Reduced State PSI Light PSI + PSII Light PSI Light Darkness Time Duysens & Amesz (1962) Cytochrome

6. Z-Scheme: Electron transfers (redox reactions)

7. Photosynthesis: Light Reactions

8. Reactions of Plastoquinones

9. Photosynthesis: Light Reactions

10. Electron Transfer in the Cytochrome b6f Complex

12. Photosynthesis: Light Reactions

13. Herbicides and the study of photosynthesis Blocks electron transfer to plastoquinone Blocks electron transfer in PSI

14. Excercises What will the status of the plastoquinone pool in DCMU treated plants? a. Reduced b. Oxidiced What will the status of the plastocyanin pool be in Paraquot treated plants? a. Reduced b. Oxidiced

15. Photosynthesis: Light Reactions

17. Today’s Topics 1.Electron transfer during the light reactions 2.Regulation of photosynthesis 3.Evolution of photosynthetic systems

18. Problems with the electron transfer process A.Excess energy absorbance B.Electron balances between PSI and PSII

19. Energy H20H20 2 H + + ½ O 2 Problems with the electron transfer process

20. PHOTOPROTECTION

21. Nonphotochemical Quenching a.Reorganization of antenna complexes b.Special carotenoids: xantophylls c.Thylakoid lumen pH

22. Problems with the electron transfer process A.Excess energy absorbance B.Electron balances between PSI and PSII

24. Energy partitioning between photosystems LHCIILHCII-P

25. Topics 1.Electron transfer during the light reactions 2.Regulation of photosynthesis 3.Evolution of photosynthetic systems

26. How does a plant make more chloroplasts? Where do the chloroplasts come from? Do all chloroplasts in all algae and plants have the same origin? Where are chloroplast proteins made?

27. What are the main open questions about the origin of oxygenic photosynthesis? Which are the current hypothesis to explain the beginning of oxygenic photosynthesis?

28. Next lecture: -Carbon reactions of photosynthesis Light Reactions ATP NADPH Carbon Reactions H 2 0 O 2 CO 2 CH 2 0