1. Review

2. C. The Calvin cycle occurs in the stroma 1. Phase 1: carbon fixation
2. Phase 2: reduction reactions
3. Phase 3: RuBP regeneration

3. CALVIN CYCLE ____ x C-C-C—P __ x C-C-C—P glucose ____ x P--C-C-C-C-C—P
____ x [3-PGA]
__ x C-C-C—P
[G-3-P]
glucose
____ x C-C-C—P
____ x P--C-C-C-C-C—P
ribulose biphosphate
___ x ADP
___ x ATP
___ Pi
___ H2O
CALVIN CYCLE
O=COH
HCOH
H2C—O—P
O=C—O—P
HOCH
____ x [G-3-P]
O=CH
[1,3-BPG]

4. 1. Phase 1: carbon fixation
CALVIN CYCLE
1. Phase 1: carbon fixation
6 x CO2
6 x H20
O=COH
HCOH
H2C—O—P
12 x
3-phosphoglycerate [3PGA]

5. 1. Phase 1: carbon fixation
a CO2 is added to a 5-C ribulose biphosphate (RuBP) to form a 6-carbon intermediate
this unstable intermediate immediately splits into two 3-C molecules of 3-phosphoglycerate (3-PGA)
enzyme involved  ribulose biphosphate carboxylase (rubisco), a very large and slow-working enzyme
this process happens 6 times to make one glucose, x (5-carbon) RuBP + 6CO  12 x (3-carbon) 3PGA
this process is called C3 photosynthesis because the first product of fixation is a 3-carbon molecule

6. Pi 2 CALVIN CYCLE O=COH HCOH H2C—O—P 12 x ATP 12 x ADP O=C—O—P HOCH
12 x [3-phosphoglycerate 3-PGA]
12 x ATP
12 x ADP
O=C—O—P
HOCH
H2C—O—P
12 x 1,3-biphosphoglycerate
[1,3-BPG]
12 x NADPH +H+ Pi
12 x NADP+
12 X glyceraldehyde-3-phosphate
[G-3-P]
O=CH
HOCH
H2C—O—P 2
x C-C-C—P
[G-3-P]
glucose

7. 2. Phase 2: reduction reactions
a series of reactions that are essentially the reverse of glycolysis
3PGA is phosphorylated to biphosphoglycerate (1,3-BPG) using ATP
1,3-BPG is reduced to glyceraldehyde-3-phosphate (G3P) by NADPH + H+ (and a Pi is lost)
1 molecule of G-3-P leaves the cycle for every 5 molecules of G3P that go on
2 molecules of G3P will combine to make 1 glucose

8. CALVIN CYCLE 6 10 x P--C-C-C-C-C—P ribulose biphosphate [RuBP] 6 x ADP
6 x ATP
4 Pi
4 H2O 10
x C-C-C—P
G-3-P

9. 3. Phase 3: RuBP regeneration
10 molecules of 3-C G3P are converted into 6 molecules of 5-C RuBP
we start with 10 phosphates (1 per G3P) and must end with 12 (2 per RuBP)
in the process 4 Pi are removed and 6 ATP are consumed
4 H2O must be added for the H and OH groups to add to the molecules

10. 4. Overall equation
6CO2 + 18ATP + 12(NADPH + H+) + 10H2O + 6RuBP 
18ADP + 16Pi +
12NADP+ +
6RuBP +
2 G3P

11. 5. Fate of G3P
chloroplast
G-3-P
glucose
starch
glucose
cellular respiration
sucrose
cellulose
transported to other parts of plant (translocation)
starch (storage)