1. Chapter 9
Energy in the Cell

2. ATP Adenosine triphosphate Quick source of energy Does not last long
The energy is stored in the bonds between the phosphates

3. Structure of the Chloroplast

4. Chloroplast Contains pigments
Molecules that absorb light of a specific wavelength
Chlorophyll – most common – absorbs most wavelengths EXCEPT green
Carotenoid – red, orange, yellow
Carotenes
Xanthophylls

5. Photosynthesis
Process that captures the sun’s energy and transforms it into simple sugars
6CO2 + 6H2O  C6H12O6 + 6O2
Occurs in the chloroplast
Two phases:
Light dependent – occurs in the membrane of the thylakoid – makes ATP
Light independent – occurs in the stoma of the chloroplast - makes simple sugars

7. Light Dependent Reactions
Requires sunlight
E from the light is transferred to e-
These excited e- enter the e- transport chain of photosystem II
Photosystem – a series of proteins embedded in the membrane of the thylakoid

8. Photosystem II and I
P II – e- is passed down the e- transport chain – makes ATP or pumps H+ into the center of the thylakoid disc at each step
P I – re-energized e- is passed down a second e- transport chain
@ the end, the e- is transferred to NADP
Forms NADPH which is used in the light- independent reactions
NADP is a carrier – it just transports the e- (like a taxi)

9. The e- Taken From the Chlorophyll Must be Replaced!
In PII water is split: photolysis
Creates oxygen, H+, and e-
Oxygen – released
H+ - pumped into the thylakoid to create a concentration gradient
e- returned to the chlorophyll

10. What happens to the H+?
An enzyme ATP synthetase allows the H to move down the concentration gradient and makes ATP

12. Light-Independent Reactions
Calvin Cycle (C3)
Make sugar from CO2
Carbon fixation
Occurs in the stroma of the chloroplast

13. C4 and CAM Used by plants in dry climates.
In dry climates, the stomata (pores) in the leaves need to stay closed to prevent water loss. This causes the CO2 levels to drop.
If not enough CO2 is available C3 plants will begin grabbing O2 and burning sugars instead of making them (photorespiration)
The protein in the light-independent rxn is more efficient at grabbing CO2