1. Photosynthesis

2. Capturing Light Energy
All energy needed by living things comes directly or indirectly from the Sun
Energy moves through organisms in a living system
Autotrophs vs. Heterotrophs
Energy is released as bonds are broken.
Some as heat the rest is stored, temporarily, as ATP.
Energy is stored when bonds are made.

3. ATP Energy storing compound Nucleotide structure
As phosphate is removed, energy is released from ATP.
ATP--> ADP + P---> AMP + P
As phosphate is added, energy is stored in ATP.
AMP + P ---> ADP + P ---> ATP

4. Photosynthesis Intro. Example of a biochemical pathway
6CO2 + 6H20 + Sunlight---> C6H12O6 + 6O2 + Energy
Reverse reaction is Cellular Respiration (chapter 7)
Use of sunlight (radiant energy) to make chemical energy (ATP)
Involves Chloroplasts located in the leaves of plants
2 types of reactions take: Light and Dark reactions

6. Chloroplasts Light reactions begin with the absorption of light
Contain a double membrane like mitochondria
Thylakoids are individual sacs stacked to form a grana and are surrounded by the stroma
Thylakoids contain pigments that absorb the different wavelengths of light
Chlorophyll a and b
Accessory pigments (carotenoids, xanthophylls)

8. Physics of Light White light contains different wavelengths of color
Visible spectrum (light) is what is seen by the eye
ROY G BIV
red region has long wavelengths
blue region has short wavelengths

9. Light Reaction AKA: Light Dependent Reaction
Photosystems II and I are involved
Light excites molecules in Photosystem II causing them to move to an electron acceptor which then passes them through an ETC to replace ‘lost’ electrons in photosystem I
Light also excites molecules in Photosystem I causing them to move to an electron acceptor which then passes them through an ETC to form NADPH
Hydrolysis of water allows for electrons to replace ‘lost’ electrons in photosystem II. Hydrogen atoms stay inside the thylakoid while Oxygen diffuses out of the chloroplast.
2H20---> 4H+ + 4e’ + O2

11. Chemiosmosis
Concentration of protons across the thylakoid causes ATP to form
ATP synthase (protein located in the thylakoid membrane) harnesses energy from concentration gradient causing ADP to add another P to make ATP
ATP synthase also acts like a carrier protein and an enzyme

13. Recap of Light Rx
Light Dependent Reactions absorb light energy in structures called thylakoids, which contain pigments.
Electrons in photosystems II and I are excited and move via the ETC
Water is split to replace ‘lost’ electrons for PS2
NADPH and ATP are made

14. Calvin Cycle AKA: Light Independent Reaction or Dark Reaction
Products made during the Light Reaction start the Dark Reaction (biochemical pathway)
Dark Reaction takes place in the stroma
Carbon Dioxide is used to make organic compounds (carbon fixation) by enzyme controlled reactions

15. CO2 joins a 5-carbon sugar called RUBP making a 6-carbon sugar
6-carbon sugar splits into 2 3-carbon sugars PGA
ATP and NADPH from the light reaction are used to convert PGA into PGAL
PGAL is converted back into RUBP using more ATP and into organic molecules

17. Recap of Dark Rx
ATP and NADPH from Light Reaction are used in the Dark Reaction
RUBP combines with a CO2 to make 2 PGA molecules
ATP then NADPH rearrange PGA into PGAL
Some PGAL is used to make organic compounds; the rest to remake RUBP so cycle can continue

18. Alternative Pathway C3 plants use Calvin cycle to fix Carbon Dioxide
C4 plants covert CO2 into a 4-carbon compound before going to calvin cycle (corn, sugar cane, crabgrass)
CAM plants close stomata during day and open them at night fixing CO2 into organic compounds to use during the day in the calvin cycle (pineapple, cactuses)

19. Rate of Photosynthesis
Rate at which a plant carries out photosynthesis is affected by the environment
Light intensity
Carbon Dioxide levels
Temperature