1. Today: -Genetics and Evolution of Photosynthetic Systems -Regulation of the Photosynthetic Machinery -Carbon reactions: Calvin-Benson cycle

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

3. Clicker question: What are the main open questions about the origin of oxygenic photosynthesis? 1.Do cyanobacteria have two photosystems? 2.How did organisms end up with two photosystems? 3. When did oxygenic photosynthesis originate? 4. Why is oxygenic photosynthesis so important? A. 1, 2 B. 3, 1 C. 2,3 D. 2,3,1 E. 4,2

4. Clicker question: Which are the current hypothesis to explain the beginning of oxygenic photosynthesis (=two PS)? 1. Microbes adapted some photosynthesis genes from other metabolic pathways. 2. Gene transfer among early photosynthetic microbes. 3. The formation of chloroplasts. 4. The evolution of one photosynthesis from the other. A. 1 B. 2 C. 1,2 D. 3,4 E. 1,2,4

5. Why is oxygenic photosynthesis such and "upgrade"?

6. Clicker question: Which of these statements is false? A. Most chloroplast proteins are imported from the cytoplasm. B. The chloroplast genome encodes most of the chloroplast proteins. C. Chloroplast genes exhibit maternal inheritance. D. Most chloroplast proteins are encoded in the nucleus.

7. Today: -Genetics and Evolution of Photosynthetic Systems -Regulation of the Photosynthetic Machinery -Carbon reactions: Calvin-Benson cycle

8. PHOTOPROTECTION "Nonphotochemical quenching"

10. Today: -Genetics and Evolution of Photosynthetic Systems -Regulation of the Photosynthetic Machinery -Carbon reactions: Calvin-Benson cycle

11. Light Reactions ATP NADPH Carbon Reactions H 2 0 O 2 CO 2 CH 2 0 Julius Sachs (~1862): 6 CO 2 + 6 H 2 O + solar energy  C 6 H 12 O 6 + O 2. Glucose/Starch

12. Calvin, Benson, Bassham (1950) C 14 CO 2 Hot ethanol

13. Malic acid Citric acid Aspartic acid PGA Sugar-P Sugar-DiP Triose phosphates PEP 30 sec Sucrose Triose phosphates Glucose

14. 5 sec Malic acid Citric acid PGA Sugar-P Sugar-DiP Triose phosphates PEP

15. CO 2 ?3PGA H | H-C-OP | H-C-COOH | H Which is the acceptor of CO 2 ?

16. CO 2 3PGA H | H-C-O-P | H-C-COOH | H Ribulose-1,5- bisphosphate H | H-C-O-P | H-C=O | H-C-OH | H-C-OH | H-C-O-P | H 2x Which enzyme catalyzes this reaction?

17. 3-Phosphoglyceric acid (3PGA) STARCH Clicker Questions What do these reactions need? A. ADP B. ATP C. NADPH D. NAPDH and ATP D. sugar Where do these occur? A. Thylacoids B. cytosol C. Stroma Is all 3-PGA converted to starch? A. Yes B. No

19. 3PGA Triose-P 1,3-Bisphosphoglycerate Glyceraldehyde-3-P

20. Topics: 1.Carbon fixation: Calvin Cycle 2.Regulation of the Calvin Cycle 3.Photorespiration

21. Regulation of the Calvin cycle Clicker Question: When should the Calvin Cycle be activated? A. Darkness B. Light C. All the time