1. 1 Classes of Lipids fatty acids triacylglycerols phospholipids Fat soluble vitamins steroids glycolipids *waxes * * fatty acids absent eicosanoids

2. 2 Functions Energy source –storage compounds (triacyl glycerols) Hydrophobic barriers –membrane constituents (phospholipids & glycoplipids) Functional –protective coverings (waxes) –regulatory properties e.g. coenzymes –hormones (steroids, prostaglandins,vitamins) –signalling e.g. odours

3. 3 1.FATTY ACIDS General structure OO C hydrophilic carboxyl group hydrophobic hydrocarbon chain Ionised at pH7amphipathic

4. 4 Aggregates of Fatty Acids Surface film micelle Hydrophobic tail Hydrophilic head water

5. 5 SATURATED FATTY ACIDS Typical example:stearic acid

6. 6 MONOUNSATURATED FATTY ACIDS e.g. OLEIC ACID - 18:1

7. 7 POLYUNSATURATED ACIDS LINOLEIC ACID - 18:2 Both bonds are cis

8. 8 Palmitic  16.0Structural Palmitoleic16.1(9)lipids and Stearic18.0 triacylglycerols Oleic acid  18.1(9) Acid name Symbol Function Butyric4:0Occur Capric10.0in milk Lignoceric24:0 Components of Nervonic24.1(15) cerebrosides Linoleic  18.2 essential fatty Linolenic18.3 acids Arachidonic20:4(5,8,11,14) Precursor of prostaglandins  predominant fatty acid residues in cells Mp C 63.1 -0.5 69.6 13.4

9. 9 Link between metabolism of carbohydrates, fats and amino acids AcetylCoA TCA Cycle Elongation Desaturation Various Fatty Acids Sugars Pyruvate glycolysis mitochondrion Palmitic acid 16.0 Amino acids AcetylCoA

10. 10 Synthesis of Fatty Acids: 2 carbon additions Palmitate 16.0 Stearate 18.0 Oleate 18.1(9) Linoleate 18.2 (9,12) Linolenate 18.3 (9,12,15) Arachidonate 20.4 (5.8.11.14) EICONASOIDS Other poly unsaturated FA elongation desaturation

11. 11 Fatty acids: Summary General formula CH 3 (CH 2 ) n COO Amphipathic Structure –C16 -20 (biological) –unsaturated / mono or polysaturated – cis configuration –branching simple Rarely free

12. 12 TRIACYLGLYCEROL

13. 13 Adipocyte nucleus triacylglycerol cytoplasm 10μm

14. 14 Sperm Whale Spermaceti organ