1. Lab Session 6 IUG, 2012 TMZ IUG, 2012 TMZ

2. Analysis of pigments and Oxidation processes in photosynthetic organisms

3. 1. Photosynthetic Organisms They contain an operative system that can selectively trap the visible light and use it in production of energy in form of ATP: This operative system includes: a.Chlorophylls b.Phycobilins c.Carotinoids

4. 2. Animal and plant cells In mitochondria of animal and plant cells, the energy is produced in a similar system (respiratory chain), where there are specific enzymes responsible for the production of energy

5. In plants… A number of high actively enzymes called oxidases is observed: 1.Peroxidases 2.Polyphenoloxidases  Such enzymes are involved in oxidation of secondary metabolites

6. Color reactions for plant pigments A. extraction of pigments from nettle leaves Principle Pigments such as chlorophyll and others have the property to dissolve in hot ethanol  Reacting with ethanol, chlorophyll is converted to ethylchlorophyllide (an ester in which the phytol is replaced by the ethanol)

7. B. Separation of pigments according to Kraus Principle Different pigments have different solubility in petroleum ether. Chlorophyll and chlorophyllide are soluble, while xanthophyl insoluble

8. C. Precipitation of chlorophyll Principle Chlorophyll ester groups are able to form a water-insoluble barium salts of chlorophyllide a & b on saponification with barium hydroxide solution  Supernatant liquid has a yellow color due to the presence of carotene and xanthophyll.

9. D. Reduction of chlorophyll with ascorbic acid Principle Ascorbic acid can reduce chlorophyll that forms a yellow color in a reduced form state.

10. E. Formation of Pheophytin from chlorophyll Principle Hydrochloric acid can bind to Mg 2+ of chlorophyll, to produce a Pheophytin that has an olive-brown color.