1. Lipids Highly diverse structures Unifying property Hydrophobic: little to no affinity to water Contains hydrocarbons, which form nonpolar covalent bonds Do not form polymers Biologically important lipids containing molecules: –Fats –Phospholipids –Steroids

2. Fats Structure –Composed of two different molecules bonded by ester linkage fatty acid & glycerol –- Fatty acid Hydrocarbon chain with a carboxyl group at one end –Glycerol Three-carbon alcohol –Each carbon attached to hydroxyl group Try to Draw

3. LE 5-11a Dehydration reaction in the synthesis of a fat Glycerol Fatty acid (palmitic acid)

4. LE 5-11b Ester linkage Fat molecule (triacylglycerol)

5. Hydrophobic H 2 O molecules form hydrogen bonds with each other and EXCLUDE fatty acid chains--> Fats separate from H 2 O (like oil & vinegar) Properties of Fats Fatty acids variable chain length (often 16-18 carbons)

6. Saturated fat - refers to saturated fatty acid chains - carbons contains maximum number of hydrogens - results in 100% single bonds (no double bonds) - more linear, packs tightly to form solid Tend to be from animals

7. LE 5-11b Ester linkage Fat molecule (triacylglycerol) Saturated or unsaturated?

8. LE 5-12a Saturated fat and fatty acid. Stearic acid Butter

9. Unsaturated fat - contains unsaturated fatty acids -carbon-carbon double bonds (>1) -irregular hydrocarbon conformation -poor packing -forms liquids (oils) at room temperature Tend to be from plants and fish

10. LE 5-12b Unsaturated fat and fatty acid. Oleic acid cis double bond causes bending Olive oil Other liquid fats (unsaturated)?

11. Phospholipids Structure –two fatty acids bonded to glycerol through ester linkage –Phosphate bonded to third hydroxyl group of glycerol Fatty acids= Hydrophobic tail Phosphate and other groups= hydrophilic head Draw schematic

12. LE 5-13 Structural formula Space-filling model Phospholipid symbol Hydrophilic head Hydrophobic tails Fatty acids Choline Phosphate Glycerol Hydrophobic tails Hydrophilic head

13. If many phospholipids were mixed in H 2 O into what structures would they self-assemble? 1.Micelle (draw) - Detergents 2.Bilayer (draw) -Cell membranes

14. LE 5-14 WATER Hydrophilic head Hydrophobic tails WATER Cellular membrane: Phospholipid Bilayer

15. Steroids Structure - Hydrophobic molecules made of 4 fused hydrocarbon rings Examples and Diverse Functions –Cholesterol Component of animal cell membranes Building block for steroid sex hormones such as –Estrogen, testosterone, progesterone High levels--> contribute to heart disease

16. Cholesterol

17. estradiol testosterone

18. Pardon me. Did you miss anything?