2. AP Biology Lipids: Fats & Oils

3. AP Biology 2006-2007 What is a Lipid? long term energy storage concentrated energy

4. AP Biology What are the characteristics of Lipids?  Lipids are composed of C, H, O  long hydrocarbon chains (H-C)  “Family groups”  Fats  Phospholipids  Steroids  Waxes  Do not form polymers  big molecules made of smaller subunits  not a continuing chain

5. AP Biology Making Butter  How do the molecules join?

6. AP Biology What is the structure of Fat?  Structure:  glycerol (3C alcohol) + fatty acid  fatty acid = long HC “tail” with carboxyl (COOH) group “head” dehydration synthesis H2OH2O enzyme

7. AP Biology How are Fats built?  Triacylglycerol  3 fatty acids linked to glycerol  ester linkage = between OH & COOH hydroxylcarboxyl

8. AP Biology Dehydration synthesis dehydration synthesis H2OH2OH2OH2OH2OH2OH2OH2O enzyme

9. AP Biology How do Fats store energy?  Long HC chain  polar or non-polar?  hydrophilic or hydrophobic?  Function:  energy storage  concentrated  all H-C!  2x carbohydrates  cushion organs  insulates body  think whale blubber! Why do humans like fatty foods?

10. AP Biology What are the characteristics of a saturated fat?  All C bonded to H  No C=C double bonds  long, straight chain  most animal fats  solid at room temp.  contributes to cardiovascular disease (atherosclerosis) = plaque deposits

11. AP Biology What are the characteristics of Unsaturated fats?  C=C double bonds in the fatty acids  plant & fish fats  vegetable oils  liquid at room temperature  the kinks made by double bonded C prevent the molecules from packing tightly together mono-unsaturated? poly-unsaturated?

12. AP Biology Saturated vs. unsaturated saturatedunsaturated

13. AP Biology What is the structure of a Phospholipid?  Structure:  glycerol + 2 fatty acids + PO 4  PO 4 = negatively charged It’s just like a penguin… A head at one end & a tail at the other!

14. AP Biology What are the characteristics of Phospholipids?  Hydrophobic or hydrophilic?  fatty acid tails =  PO 4 head =  split “personality” interaction with H 2 O is complex & very important! “repelled by water” “attracted to water” Come here, No, go away! hydrophobic hydrophillic

15. AP Biology How do Phospholipids act in water?  Hydrophilic heads “attracted” to H 2 O  Hydrophobic tails “hide” from H 2 O  can self-assemble into “bubbles”  bubble = “micelle” (pronounced "my sell" or "my seal”)  can also form a phospholipid bilayer  early evolutionary stage of cell? bilayer water

16. AP Biology Why is this important?  Phospholipids create a barrier in water  define outside vs. inside  they make cell membranes!

17. AP Biology What is the structure of a steroid?  Structure:  4 fused C rings + ??  different steroids created by attaching different functional groups to rings  different structure creates different function  examples: cholesterol, sex hormones cholesterol

18. AP Biology Why are Steroids like Cholesterol needed?  Important cell component  animal cell membranes  precursor of all other steroids  including vertebrate sex hormones  high levels in blood may contribute to cardiovascular disease

19. AP Biology Cholesterol helps keep cell membranes fluid & flexible Important component of cell membrane

20. AP Biology From Cholesterol  Sex Hormones  What a big difference a few atoms can make!

21. AP Biology 2006-2007 Let’s build some Lipids!

22. AP Biology 2007-2008 Ghosts of Lectures Past (storage)

23. AP Biology Phospholipids & cells  Phospholipids of cell membrane  double layer = bilayer  hydrophilic heads on outside  in contact with aqueous solution outside of cell and inside of cell  hydrophobic tails on inside  form core  forms barrier between cell & external environment How does soap work? Required Reading