1. Photosynthesis: Light-Independent Stage

2. Building Sugars What products came from the light-dependent reactions?
ATP and NADPH
Light-independent reactions use ATP and NADPH to build sugars from CO2
ATP energy source
NADPH high energy electrons and H+
Where do these reactions happen?
Stroma of the chloroplasts
Who mapped it out?
Melvin Calvin (called Calvin Cycle)

3. The Calvin Cycle: Part 1 Where do we also find GP?
CO2+ATP+NADPHADP+Pi+NADP++glyceraldehyde-3-phosphate(GP)
Where do we also find GP?
Half-way point in glycolysis
Can start glycolysis from here
Phase 1: Carbon Fixation
CO2 is fixed to 1,5-bisphosphate (RuBP) by the enzyme RuBP carboxylase/oxygenase (rubisco) creating a 6-C sugar
6-C is broken into two 3-phosphateglycerates (PGA)

4. The Calvin Cycle: Part 2 Phase 2: Reduction
3) NADPH and ATP supply the energy, electrons, and H+ needed to change PGA into GP
How many GP do we have? 2
How many do we need to make glucose?
Why do plants NOT just make sugar with the 2 GP?
Need to regenerate RuBP or cycle shuts down
Where have we seen this before?
Oxaloacetate in the Krebs cycle

5. The Calvin Cycle: Part 3 Phase 3: Regeneration
4) GP molecules will be used to build RuBP molecules
3 turns of the cycle will produce 6 GP but 5 will be used to place the RuBP used; the left over G3P is used to build sugars
3 Turns:
- 3 CO2 and 3 RuBP (5-C)  18 C
- 6 GPs produced
- 5 GPs 15 C 3 RuBP
- Last GP builds a sugar
How many turns are needed to make glucose?
6! That is really complex
How many ATP are used to make glucose?
18 ATP (3 ATP/Turn; 6 Turns)

6. Calvin Cycle: Regulation
What is used to regulate the cycle?
ATP and NADPH levels
What enzyme do they effect?
Rubisco
Rubisco is found in all photosynthetic organisms and up to 50% of all proteins in a leaf; most abundant protein on Earth (6kg/person)
What does the name RuBP carboxylase/oxygenase tell you about the enzyme?
Reacts with both CO2 and O2
Competitively inhibit each other

7. The Problem with Gas Exchange
How does CO2 and O2 get in and out of a plant?
Stromata under the leaves
What else can escape through a stromata that the plant needs?
H2O
What problems must plants in dry, hot climates deal with?
The plant needs to take in CO2 and release O2, but the open stromata will also release H2O
H2O out

8. Homework Read Ch 10 and do Ch 10 vocabulary Do Ch 9 vocabulary
“Test Your knowledge” for Ch 9 and “Apply Evolutionary Thinking”
Lab reports due next Thursday
Ch 10 and 11 are left and then a test on Ch 9, 10 and 11