1. Figure 10.0 Sunbeams

2. Fig. 10-2 (a) Plants (c) Unicellular protist 10 µm 1.5 µm 40 µm (d) Cyanobacteria (e) Purple sulfur bacteria (b) Multicellular alga THE BASIS OF ECOSYSTEMS ARE AUTOTROPHS, ORGANISMS THAT CAN SYNTHESIZE ORGANIC MOLECULES USING SUNLIGHT AS A SOURCE OF ENERGY.

3. Overall photosythesis rxn: 6 CO 2 + 6 H 2 O → C 6 H 12 O 6 + 6 O 2  Objective of photosynthesis: Synthesize carbohydrates from CO 2 and H 2 O  Photosynthesis is reverse of respiration in overall rxn  Light energy is added to drive rxn  Detailed pathways are NOT reverse; different specific mechanisms

4. Link to mitochondria and chloroplasts

5. Figure 10.4 An overview of photosynthesis: cooperation of the light reactions and the Calvin cycle (Layer 1)

6. Figure 10.4 An overview of photosynthesis: cooperation of the light reactions and the Calvin cycle (Layer 2)

7. Figure 10.4 An overview of photosynthesis: cooperation of the light reactions and the Calvin cycle (Layer 3)

8. Figure 10.2 Focusing in on the location of photosynthesis in a plant

9. Figure 10.4 An overview of photosynthesis: cooperation of the light reactions and the Calvin cycle (Layer 3)

10. Link to VA Tech Photosynthesis Animation

11. Figure 10.5 The electromagnetic spectrum

12. Figure 10.6 Why leaves are green: interaction of light with chloroplasts

13. Figure 10.7 Determining an absorption spectrum

14. Spectrum of White Light (continuous spectrum); Emission and Absorption Spectrum of Hydrogen

15. Quantum Links Link to Phet Laser quantum

16. Absorption Spectra of a Molecule is much more complex than a single type of atom due to numerous overlapping quantized electronic transitions of valence electrons. (Many different vibrational and rotational motions possible in a big molecule )

17. Molecules that have alternating single and double bonds (resonance delocalization) tend to absorb visible and ultraviolet light; absorption of low energy visible light is due to transitions of weakly bonded pi bonding electrons from ground to excited states. PABA (sunscreen)Chlorophyll a

18. Pi bonding electrons are farther from nuclei and therefore more weakly attracted than sigma bonding electrons

19. Figure 10.9 Location and structure of chlorophyll molecules in plants Chlorophyll a and Cholorphyll b are the most important light absorbing molecules in photosynthesis

20. Figure 10.10 Excitation of isolated chlorophyll by light

21. Figure 10.8 Evidence that chloroplast pigments participate in photosynthesis: absorption and action spectra for photosynthesis in an alga Light Absorption of different plant pigments at different wavelengths Rate of photosynthesis at different wavelengths

22. Figure 10.8 Evidence that chloroplast pigments participate in photosynthesis: absorption and action spectra for photosynthesis in an alga Compare absorption spectrum of chlorophyll a to action spectrum Note photosynthesis is effective at more wavelengths than just those where chlorophyll a has high absorbance Key conclusion: Chlorophyll a and Chlorophyll b are responsible for a significant fraction of light absorption in photosynthesis but not all. Presence of additional pigments insures greater range of visible light wavelengths can be used by plant.