2 long term energy storage Lipidslong term energy storageconcentrated energy
3 Lipids Lipids are composed of C, H, O “Family groups” long hydrocarbon chains (H-C)“Family groups”fatsphospholipidssteroidsDo not form polymersbig molecules made of smaller subunitsnot a continuing chainMade of same elements as carbohydrates but very different structure/ proportions & therefore very different biological properties
4 dehydration synthesis FatsStructure:glycerol (3C alcohol) + fatty acidfatty acid = long HC “tail” with carboxyl (COOH) group “head”enzymeLook at structure… What makes them hydrophobic?Note functional group = carboxylH2Odehydration synthesis
5 Building Fats Triacylglycerol 3 fatty acids linked to glycerol ester linkage = between OH & COOHhydroxylcarboxylBIG FAT molecule!!
6 Dehydration synthesis H2Odehydration synthesisenzymeH2OPulling the water out to free up the bondenzymeH2OenzymeH2O
7 Why do humans like fatty foods? Fats store energyLong HC chainpolar or non-polar?hydrophilic or hydrophobic?Function:energy storageconcentratedall H-C!2x carbohydratescushion organsinsulates bodythink whale blubber!What happens when you add oil to waterWhy is there a lot of energy stored in fats?• big molecule• lots of bonds of stored energySo why are we attracted to eating fat?Think about our ancestors on the Serengeti Plain & during the Ice Age. Was eating fat an advantage?
8 Saturated fats All C bonded to H No C=C double bonds long, straight chainmost animal fatssolid at room temp.contributes to cardiovascular disease (atherosclerosis) = plaque depositsMostly animal fats
9 Unsaturated fats C=C double bonds in the fatty acids plant & fish fats vegetable oilsliquid at room temperaturethe kinks made by double bonded C prevent the molecules from packing tightly togetherMostly plant lipidsThink about “natural” peanut butter:Lots of unsaturated fats Oil separates outCompanies want to make their product easier to use:Stop the oil from separating Keep oil solid at room temp.Hydrogenate it = chemically alter to saturate itAffect nutrition?mono-unsaturated?poly-unsaturated?
11 It’s just like a penguin… PhospholipidsStructure:glycerol + 2 fatty acids + PO4PO4 = negatively chargedIt’s just like a penguin…A head at one end& a tail at the other!
12 Phospholipids Hydrophobic or hydrophilic? fatty acid tails = PO4 head =split “personality”hydrophobichydrophillic“attracted to water”Come here, No, go away!interaction with H2O is complex & very important!“repelled by water”
13 Phospholipids in water Hydrophilic heads “attracted” to H2OHydrophobic tails “hide” from H2Ocan self-assemble into “bubbles”bubble = “micelle”can also form a phospholipid bilayerearly evolutionary stage of cell?waterbilayerwater
14 Why is this important? Phospholipids create a barrier in water define outside vs. insidethey make cell membranes!Tell them about soap!
15 Steroids Structure: 4 fused C rings + ?? different steroids created by attaching different functional groups to ringsdifferent structure creates different functionexamples: cholesterol, sex hormonescholesterol
16 Cholesterol Important cell component animal cell membranes precursor of all other steroidsincluding vertebrate sex hormoneshigh levels in blood may contribute to cardiovascular disease
17 Cholesterol Important component of cell membrane helps keep cell membranes fluid & flexible
18 From Cholesterol Sex Hormones What a big difference a few atoms can make!Same C skeleton, different functional groups
21 Phospholipids & cells Phospholipids of cell membrane double layer = bilayerhydrophilic heads on outsidein contact with aqueous solution outside of cell and inside of cellhydrophobic tails on insideform coreforms barrier between cell & external environmentPhospholipid bilayerNote other molecules in membrane…Tell them about soap!