1. Photosynthesis By: Muhammad Iqbal Khan SS BiologyID
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2. Lecture 3 Outline (Ch. 8) Photosynthesis overview
A. Purpose
B. Location
The light vs. the “dark” reaction
Chloroplasts pigments
A. Light absorption
B. Types
Light reactions
A. Photosystems
B. Photophosphorylation
V. The light independent reaction (“dark” reaction)
A. Carbon “fixation”
B. Reduction
C. Regeneration
VI. Alternative plants

3. Photosynthesis - overview

4. Photosynthesis - overview
Overall purpose:
• photosynthesis –
light chemical energy
• complements respiration
Energy for all life on earth ultimately comes from photosynthesis

5. Cellular Respiration vs. Photosynthesis
(Exergonic)
Photosynthesis:
(Endergonic)

6. Photosynthesis – chloroplast recap
Outer membrane
Inner membrane
Thylakoid membrane
Stroma
Thylakoid space
Intermembrane space

7. Photosynthesis - overview
1. light rxn: store energy & split water – “photo”
NADPH & ATP
2. dark rxn: “fix” CO2 & make sugars – “synthesis”
Calvin cycle

8. Redox Reactions 6CO2 + 12H2O + light energy C6H12O6 + 6O2 + 6H2O
Equation for photosynthesis

9. Photosynthesis - overview
• light reactions:
• dark reactions:
– thylakoid membrane
– stroma
Light
H2O
Chloroplast
Reactions
NADP+ P
ADP +
ATP
NADPH O2
Calvin
Cycle
CO2
[CH2O]
(sugar)
– thylakoid space

10. Photosynthesis – light absorption
• visible light ~380 to 750 nm
• chloroplast pigments – abs blue-violet & red
- transmit and reflect green

11. Photosynthesis – light absorption
• pigments:
• chlorophyll a
-energy-absorbing ring
-hydrocarbon tail
• accessory pigments
- chlorophyll b
- carotenoids
- photoprotective

12. Interesting, right?
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