1. Photosynthesis

2. The Essence of Photosynthesis
• energy from sunlight is converted into chemical bond energy in the form of carbohydrates
2. Summary equation for photosynthesis

3. The Essence of Photosynthesis cont.
3. Principle ingredients
a. Carbon dioxide (CO2)
b. Water
c. Light
d. Chlorophyll
1) Several types
2) All magnesium containing molecules
3) Light harvesting complex called a photosynthetic unit
• pigment molecules

4. The Essence of Photosynthesis cont.
3. Principle ingredients
a. Carbon dioxide (CO2)
b. Water
c. Light
d. Chlorophyll
1) Several types
2) All magnesium containing molecules
3) Light harvesting complex called a photosynthetic unit
• pigment molecules

5. Introduction to the Major Steps of Photosynthesis
1. The Light-Dependent Reactions
a. Reactions take place in thylakoid membranes of chloroplast
• light required
b. Water split, producing hydrogen ions and electrons, O2 gas released
c. ATP created
d. NADPH + H+ created

6. Introduction to the Major Steps of Photosynthesis

7. Introduction to the Major Steps of Photosynthesis
2. The Light-Independent Reactions (Calvin cycle)
a. Reactions take place in stroma of chloroplast
• light not required, hence "dark" reactions
b. Calvin cycle
1) Carbon dioxide from air combined with 5-carbon sugar
2) Glucose formed through several reaction steps

8. Introduction to the Major Steps of Photosynthesis

9. Label the components of the chloroplast and what they do.
Grana – light reaction
Stroma – dark reaction
Light trapping system
E trapped and guided down to chloroplast
2 main kinds of chlorophyll: a, and b
All light energy is transported to chlorophyll a which does the task.
B to a
C to a
Other pigments to a

10. spectrum
Leaves absorbe the red and blue end of the spectrum. That is why leaves look green.

11. Accessory pigments to trap light E
Xanthophylls – yellow antioxidant
Carotene – orange antioxidant

12. A Closer Look at Photosynthesis
1. Historical perspective
2. The Light-Dependent Reactions Reexamined
a. Nature of light
1) Wave and particle theory of light
2) Photoelectric effect
3) Photons
• discrete packets of light energy

13. A Closer Look at Photosynthesis cont.
b. Chlorophyll pigments
• each pigment has typical absorption spectrum
c. Consequences of light absorption by chlorophyll
1) Emit light immediately (fluorescence)
2) Emit light after a delay (phosphorescence)
3) Absorbed energy converted to heat
4) Absorbed energy converted and stored in chemical bond energy (photosynthesis)

14. A Closer Look at Photosynthesis cont.
d. Photosystem I contains
1) 200 or more chlorophyll a molecules
2) Small amount of chlorophyll b
3) Carotenoid pigment with protein attached
4) Special reaction-center molecule of chlorophyll a called P700
5) Iron-sulfur proteins (electron acceptors)

15. A Closer Look at Photosynthesis cont.
e. Photosystem II contains
1) Chlorophyll a molecules
2) ß-carotene pigments attached to protein
3) Small amount of chlorophyll b
4) Special reaction-center molecule of chlorophyll a called P680
5) Primary electron acceptor molecule called pheophytin
F. Photolysis
g. Photophosphorylation
h. Chemiosmosis

16. A Closer Look at Photosynthesis cont.
3. The Light-Independent Reactions Re-examined
a. The Calvin cycle (3-carbon pathway)
b. Photorespiration
c. The 4-carbon pathway
d. CAM photosynthesis
4. Other Significant Processes that Occur in Chloroplasts

17. The Essence of Respiration
1. Respiration defined
• energy releasing process where simple sugars are broken down during a series of stages controlled by enzymes
2. Summary equation for respiration
3. Anaerobic respiration and fermentation

18. Introduction to the Major Steps of Respiration
1. Glycolysis
2. Aerobic respiration
a. The Citric Acid (Krebs) Cycle
b. The Electron transport chain
3. Anaerobic respiration and fermentation
4. Factors affecting the rate of respiration
a. Temperature
b. Water
c. Oxygen

19. A Closer Look at Respiration
1. Glycolysis re-examined
a. Phosphorylation
b. Sugar cleavage
2. Transition Step to the Citric Acid (Krebs) Cycle
a. Pyruvic acid
b. Acetyl CoA
3. The Krebs cycle re-examined
4. Electron transport and oxidative phosphorylation

20. END