1. Photosynthesis Making Organic Molecules

2. Overview

3. Light-Dependent Reactions Absorption of Light by Chlorophyll

4. Light-Dependent Reactions

5. Non-Cyclic Electron Transport

6. Cyclic Electron Transport Light-Dependent Reactions

8. Light Independent Reactions Calvin Cycle Calvin-Benson Cycle Dark Reactions

9. Light Independent Reactions RuBP Carboxylase PGA

10. “C-3 Plants” Calvin Cycle results in 3-carbon PGA. Problem: Photorespiration –When CO 2 levels are low… –O 2 combines with RuBP instead of CO 2 –Product splits, and breaks apart, releasing CO 2 and NO ATP! –Inefficient – less sugar…less energy! Little PGA is produced – the precurser to sugar.

11. Solution?... Alternate Pathways for CO 2 fixation have evolved! C-4 plants –Carbon fixation results in a 4-carbon molecule: Oxaloacetate (OAA). –C-4 pathway in mesophyll cells, Calvin Cycle in bundle-sheath cells. CAM plants –Crassulacean Acid Metabolism –C-4 pathway by night, Calvin Cycle by day

12. C-4 plants & CAM plants

13. Alternate pathways for CO 2 fixation! Read pp. 195-197.