1. ARE LIPIDS BAD FOR US? GOOD VS. BAD

2. Lipids are a diverse group of hydrophobic molecules Lipids are the one class of large biological molecules that do not form polymers All lipids contain large chains of nonpolar hydrocarbons (chains of carbon and hydrogen) Lipids are hydrophobic and water insoluble The most biologically important lipids are fats (triglycerides), phospholipids, and steroids Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

3. Fats Fats are constructed from two types of smaller molecules: glycerol and fatty acids Glycerol is a three-carbon alcohol with a hydroxyl group attached to each carbon A fatty acid consists of a carboxyl group (COOH) attached to a long carbon skeleton Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fat molecule (triacylglycerol)

4. Saturated fatty acids have the maximum number of hydrogen atoms possible and no double bonds Unsaturated fatty acids have one or more double bonds Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

5. Saturated fats are solid at room temperature Most animal fats are saturated Found in soaps, candles, lotion, creams, etc Unsaturated fats or oils are liquid at room temperature Plant fats and fish fats are usually unsaturated Found in avocado, almonds, macadamia nuts, etc Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

9. FATS Stored as adipose tissue under skin, around kidneys, within abdomen, etc Long term energy source/long term energy storage Provides insulation, and protection around organs

10. Phospholipids In a phospholipid, two fatty acids and a phosphate group are attached to glycerol The two fatty acid tails are hydrophobic, but the phosphate group and its attachments form a hydrophilic head Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

11. Fig. 5-14 Hydrophilic head Hydrophobic tail WATER

12. Regulates the amount of material that goes in/out of cells. Provides flexibility and fluidity to cell membrane allowing formation of vesicles.

13. Steroids Steroids are lipids characterized by a carbon skeleton consisting of four fused rings Steroids all have a 17 carbon atom skeleton Cholesterol, an important steroid, is a component in animal cell membranes Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

14. Cholesterol: – Insoluble in blood so carried by lipoproteins – HDL = good cholesterol, picks up cholesterol and takes to liver – LDL = bad cholesterol, forms plaque in arteries

15. State three functions of lipids

16. Compare the use of carbohydrates and lipids in energy storage