Calvin Cycle & Alternate Pathways

1. Calvin Cycle & Alternate Pathways Chapter 10.3-10.4

2. Learning Target 3 (10.3) I can describe how the Calvin cycle uses ATP and NADPH to convert carbon dioxide to sugar.

3. Calvin Cycle Part of photosynthesis that makes glucose

4. Light Independent Reactions (Calvin Cycle) • NADPH and ATP generated in light dependent reactions run the Calvin Cycle • Depends on light reactions even though it happens in light and dark • Many cycles produce glucose (C6H12O6)

5. 3 Stages • Carbon fixation • CO2 gas is incorporated using rubisco enzyme, creating 3-phosphoglycerate • Most abundant protein on Earth! • Reduction • ATP, NADPH provide energy to reduce 3-phosphoglycerate into sugar (CH2O) • Regeneration of CO2 acceptor (RuBP) • RuBP is prepared to receive next CO2

7. Calvin Cycle Summary • Reactants: • NADPH • ATP • CO2 • Products: • NADP+ • ADP + Pi • CH2O  C6H12O6

8. Calvin Cycle Animation • http://highered.mcgraw-hill.com/sites/0070960526/student_view0/chapter5/animation_quiz_1.html

9. PS overview video • http://www.youtube.com/watch?v=g78utcLQrJ4

10. Photosynthesis Overview

11. Alternate Pathways 10.4

12. Evolution of PS • Life on land comes with benefits and risks • Benefits? • Risks?

13. C3 Plants • Examples: rice, wheat, soybeans • Carbon fixation in Calvin cycle with rubisco • Photorespiration • Stomata close  decrease of CO2  rubisco fixes O2 instead  releases CO2 • No ATP, decreased PS output… but protects plants in high light environments

14. C4 Plants • Examples: corn, sugarcane, grasses • PEP carboxylase fixes CO2 4C compound • 4C compound  CO2 released to rubisco, 3C compound regenerated • Allows plant to stockpile CO2 while stomata are closed during the day

15. CAM Plants • Examples: jade, pineapple, orchids • Stomates open at night, take in CO2 stored as an organic acid for use during the day