AP Biology Lipids: Fats & Oils

AP Biology Lipids  Lipids are composed of Carbon, Hydrogen, and small amts of Oxygen  long hydrocarbon chains (H-C)  Do not form polymers  They are big molecules made of smaller subunits  not a continuing chain

AP Biology Lipid Functions long term energy storage Insulation Waterproofing Hormone Production

AP Biology Fats  Structure:  Fats, Oils and Waxes are made of a Glycerol molecule (3-Carbon alcohol) + fatty acid  fatty acid = long Hydrogen/Carbon “tail” with carboxyl (COOH) group head dehydration synthesis H2OH2O enzyme

AP Biology Building Fats  Triacylglycerol  3 fatty acids linked to glycerol  ester linkage = between OH & COOH…links a glycerol to fatty acids. hydroxyl carboxyl

AP Biology Dehydration synthesis dehydration synthesis H2OH2OH2OH2OH2OH2OH2OH2O enzyme

AP Biology Fats store energy  Long Fatty Acid Tail  It is non-polar  Hydrophobic (repels water)  Function:  energy storage  2x what is given in carbohydrates  cushion organs  insulates body  think whale blubber!

AP Biology Saturated fatty acids  All Carbon bonded to Hydrogen  No C=C double bonds  long, straight chain  most animal fats  solid at room temp.  contributes to cardiovascular disease = plaque deposits

AP Biology Unsaturated fatty acid tail  C=C double bonds in the fatty acids  plant & fish fats  vegetable oils  liquid at room temperature  the kinks made by double bonded Carbon prevent the molecules from packing tightly together

AP Biology Saturated vs. unsaturated saturatedunsaturated

AP Biology Phospholipids  Structure:  Made of a glycerol molecule + 2 fatty acids + PO 4 (phosphate group)  PO 4 = negatively charged

AP Biology 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” hydrophobic hydrophillic (attracted to water)

AP Biology Phospholipids in water  Hydrophilic heads “attracted” to H 2 O  Hydrophobic tails “hide” from H 2 O  can self-assemble into “bubbles”  bubble = “micelle”  can also form a phospholipid bilayer  early evolutionary stage of cell? bilayer water

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

AP Biology Steroids  Structure:  4 fused Carbon rings + One Functional Grp??  different steroids created by attaching different functional groups to rings  Important: different structure = different function  examples: cholesterol, sex hormones cholesterol

AP Biology Cholesterol- type of Steroid  Important cell component  animal cell membranes - keeps fatty acid tails from sticking together  precursor of all other steroids  including vertebrate sex hormones  high levels in blood may contribute to cardiovascular disease

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

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

AP Biology LIPIDS  All Lipids are INSOLUBLE in water!