Lipids Fats Oils AP Biology Lipids Lipids are

Lipids: Fats & Oils AP Biology

Lipids § Lipids are composed of C, H, O u long hydrocarbon chains (H-C) § “Family groups” fats u phospholipids u steroids u § Do not form polymers big molecules made of smaller subunits u not a continuing chain u AP Biology

Fats § Structure: u glycerol (3 C alcohol) + fatty acid § fatty acid = long HC “tail” with carboxyl (COOH) group “head” H 2 O dehydration synthesis AP Biology

Building Fats § Triacylglycerol 3 fatty acids linked to glycerol u ester linkage = between OH & COOH u hydroxyl AP Biology carboxyl

Fats store energy § Long HC chain u non-polar and hydrophobic § Function: u energy storage § concentrated w all H-C! § 2 x carbohydrates cushion organs u insulates body u § think whale blubber! AP Biology

Saturated fats § All C bonded to H § No C=C double bonds long, straight chain u most animal fats u solid at room temp. u § contributes to cardiovascular disease (atherosclerosis) = plaque deposits AP Biology

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

Saturated vs. unsaturated AP Biology

Phospholipids- cell membrane § Structure: u glycerol + 2 fatty acids + PO 4 § PO 4 = negatively charged AP Biology

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

Other lipids: u Vitamins § u acquired from diet Plant pigments § Carotenoids § Beta carotene- photosynthetic pigment u Waxes § Ear, leaf wax, honeycombs structure u AP Biology Steroids

Steroids § Structure: u 4 fused C rings + ? ? § different steroids created by attaching different functional groups to rings § different structure creates different function u examples: cholesterol, sex hormones cholesterol AP Biology

Cholesterol § Important cell component animal cell membranes u precursor of all other steroids u § including vertebrate sex hormones u AP Biology high levels in blood may contribute to cardiovascular disease

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

Proteins Carbohydrates Lipids § Any questions? AP Biology

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

Phospholipids & cells § Phospholipids of cell membrane u u double layer = bilayer hydrophilic heads on outside § in contact with aqueous solution outside of cell and inside of cell u hydrophobic tails on inside § form core u forms barrier between cell & external environment Tell them about soap! AP Biology