1. The Calvin Cycle Anabolic reaction (builds sugar)
Requires ATP and NADPH (reducing power)
Requires 9 ATP and 6 NADPH (which are regenerated by light reactions)
Carbon enters in the form of CO2 and exits as a glucose molecule
For every three molecules of CO2, one G3P(sugar) is produced (net gain)

2. Phases of The Calvin Cycle
Phase I: Carbon Fixation
CO2 attaches to a five-carbon sugar ribulose biophosphate (RuBP)
Enzyme (RuBP carboxylase aka rubisco most abundant protein) catalyzes this reaction
Produces a six carbon molecule but is unstable and split to form a three carbon molecule
3-phosphoglycerate
**For each CO2 molecule

4. Phase II: Reduction
Each 3-phosphoglycerate receives an additional phosphate group
Enzyme transfers phosphate from ATP to the molecule
A pair of electrons donated from NADPH reduces the molecule to G3P (potential energy)

6. Phase III: Regeneration of CO2 acceptor RuBP
five molecules of G3P are arranged into three molecules of RuBP
uses 3 ATP molecules to do this
RuBP is now prepared again to receive CO2 and the cycle continues

7. What would happen if you closed the stomata on a leaf?
Build up of oxygen
No water would be released
No carbon dioxide would enter
Why would a plant close its stomata?
Hot dry environments (prevent dehydration)
But this limits photosynthesis production

8. Alternate Methods of Carbon Fixation
Photorespiration:
C3 plants (most plants)
Produce G3P by fixating carbon using rubisco. Examples:Rice, wheat, soybean

9. Stomata close therefore CO2 decreases and O2 increases
Rubisco adds O2 to the Calvin Cycle which forms two carbon molecule broken down by mitochondria/peroxisomes into CO2
Process is called photorespiration
No ATP is generated
No food is generated
Seems wasteful

10. Modern Plants have Evolved
C4 Plants
Produces a four carbon molecule
Examples: sugarcane, corn, grass

11. Contain two types of photosynthetic cells
Bundle sheath cells
Mesophyll cells

12. CO2 is added to PEP (phosphoenopyruvate)
Enzyme PEP carboxylase combines the two due to enzymes high affinity for CO2
After C4 plants fixes CO2 then the mesophyll cells exports the four carbon into bundle sheath cells
Enhances sugar production (b/c CO2 is available)

13. CAM Plants (Crassulacean Acid Metabolism)
Cacti, pineapples

16. CAM Plants (Crassulacean Acid Metabolism)
Cacti, pineapples
open stomata at night
CO2 gained at night forms organic acid
Mesophyll cells of CAM plants store the organic acid
During daylight CO2 (from organic acid) is released into the bundle sheath and made into sugar

17. ** CAM, C3 and C4 plants all eventually use the Calvin Cycle to make sugar from CO2