1. Light and Pigments

2. Properties of Light Part of the electromagnetic spectrum Travels as waves Light is composed of photons  Particles of energy  Energy is inversely proportional to wavelength

3. Electromagnetic Spectrum

4. Chloroplasts Found mainly in cells of mesophyll Double membrane  Inner membrane surrounds fluid- filled stroma – contains enzymes for carb production Within stroma is 3 rd system of membranes – forms thylakoids

5. Thylakoid membrane encloses thylakoid lumen Thylakoids may be arranged in stacks called grana Thylakoid membrane involved in ATP synthesis

6. Pigments Substances that absorb visible light Different pigments absorb different wavelengths  Wavelengths not absorbed are reflected or scattered – that’s the color you see

7. When photon strikes an atom/molecule, electron may move to a higher energy level http://earthguide.ucsd.edu/earthguide/diag rams/absorption/absorption.html http://earthguide.ucsd.edu/earthguide/diag rams/absorption/absorption.html Electron can either  Return to ground state  Leave atom and transfer to carrier molecule

8. Chlorophyll is main pigment of photosynthesis 2 main parts:  Ring  H-C tail Several kinds  Chlorophyll a main one Absorbs light in red and blue regions of spectrum

9. Absorption of chlorophyll

10. Accessory pigments Chlorophyll a (bright green) initiates light- dependent reactions of photosynthesis, other pigments participate as well Accessory pigments:  Chlorophyll b (yellow-green)  Carotenoids – yellow and orange

11. Action spectrum Graph of effectiveness of different wavelengths of light