1. Lecture 13 FATTY ACIDS and Steroids Convener Dr. Fawaz Aldabbagh

2. Lipids – water insoluble compounds Excess carbohydrate (high energy foods) are stored as lipids, called fats. No definite structural grouping – include fats, oils, waxes, steroids + derivatives Uses – Insulation, protection, help maintain correct body temperature, covering of nerve fibres + major structural material in cells Two major groups – Saponifiable lipids and Non- Saponifiable lipids Fatty Acids – naturally occurring long chain carboxylic acids Unbranched carbon chain with an even number of carbon atoms

3. Long-chain fatty acids – 12-26 carbons are found in meat and fish Medium-chain fatty acids – 6-10 carbons Short-chain fatty acids – less than 6 are found in dairy products This is an example of a saturated fatty acid

4. Polyunsatuarated – have a carbon chain in which two or more DBs are present These are Essential Fatty Acids

5. Fats and Oils are Esters 1,2,3-Propanetriol

6. Fused Bicyclic Systems cis is the same side trans opposite sides

7. Steroids can be isolated from the lipid fractions of animals and plants Most show dramatic physiological effects when administered Cholestanol

8. Isolated from nearly all animal tissues Gallstones are particularly rich in cholesterol Intermediate in the biosynthesis of other steroids 8 stereocenters 2 8 = 256 possible isomeric forms

9. Sex Hormones 1. The female sex hormones (estrogens) 2. The male sex hormones (androgens) 3. The pregnancy hormones (progrestins)

10. Sun-light helped to cure rickets Ergosterol was isolated from yeast And was found to be highly active