Photosynthesis part deux: The Calvin Cycle

1. Photosynthesis part deux: The Calvin Cycle Chapter 6-2 pages 117-120 At right is Melvin Calvin who worked all this out Below is Calvin who worked out Calvin Ball

2. Objectives • Summarize the main events of the calvin cycle • Describe what happens to the compounds that are made during the calvin cycle • Distinguish between c3, c4, and CAM plants • Summarize how the light and dark reactions work together in photosynthesis • Explain how environmental factors affect photosynthesis

3. From photosynthesis we get ATP and NADPH Now we’ll use the energy from that to make biomolecules The energy from Niagra falls is used to power turbines so we can use electricity to do work Calvin Cycle

4. Carbon Fixation • Carbon fixation is the building of biomolecules from CO2 • 3 steps of the Calvin Cycle 1. CO2 diffuses into the stroma from the surrounding cytoplasm. RuBP is combined with CO2. The new 6 Carbon molecule splits into 2 3 Carbon molecules called PGA

5. Step 2 2 PGAs converted to another 3 Carbon molecule PGAL, in a two part process 1. PGA receives a Phosphate from ATP 2. NADPH gives its H+ The ADP, NADP+, and Phosphate are reused back in the photosynthesis reaction Confused, stare at this picture, watch the lines seem to move. Now get back to work Calvin Cycle

7. Calvin Cycle Step 3 Some of the PGAL goes back to RuBP so the Cycle can continue Other PGAL goes elsewhere to make Biomolecules

8. Calvin Cycle has to turn 3 times to get a PGAL That uses 9 ATPs and 6 NADPHs Now no glucose has been made yet. Cellular respiration is where Glucose is involved. The Lakers appreciate the Calvin Cycle, you should to. Balance sheet for Photosynthesis

9. Alternative pathways • C3 Plants only fix carbon through the Calvin Cycle • Most plants are this, trees for example • In hot climates plants lose water through open stomata so they need to keep stomata closed • But stomata are where CO2 & O2 leave and enter the cell

10. Alternative Pathways • C4 pathway plants put CO2 into 4 carbon molecules • Corn & Sugar Cane are examples • CAM pathway plants have stomata open at night and closed during the day, the opposite as normal • includes Cactus & Pineapple