Lipids

Macromolecule #2: Lipids  Hydrophobic (nonpolar) = insoluble in water  Contain C, H, O (less O than carbs), sometimes P Main types: Triglycerides (fats & oils) Phospholipids Steroids

1. Triglycerides (fats & oils) Saturated = each C has 4 single covalent bonds with H Unsaturated = presence of one or more double bonds Contain glycerol + three fatty acids FUNCTIONS: Energy storage, cushioning, insulation

The bad saturated fat  Large amounts of saturated fat increase the risk of heart disease  ↑ both LDL (“bad” lipoprotein) & HDL (“good” lipoprotein)  LDL may deposit cholesterol on arteries; HDL carries cholesterol from blood to liver where it may be stored Found in fats of mostly animal origin

Unsaturated oils = the good lipids Found in olive oil, canola oil, peanut oil, fish oil, nuts ↓ LDL (bad lipoprotein)

Hydrogenated fats = the worst guys Also called trans fats; hydrogens are added synthetically to unsaturated oils to make them solids at room T margarine, crisco ↑ LDL and ↓ HDL

2. Phospholipids Found in cell membranes

3. Steroids Functions of cholesterol: 1. Increases stability of all animal cell membranes 2. Needed to make bile (bile is needed for digestion of fats) 3. Precursor to steroid hormones, e.g. testosterone, estrogen, calcitriol

4. Other Lipids Eicosanoids – “local hormones”; LOTS of functions:  Contribute to inflammatory and immune response  Control other hormones  Prevent stomach ulcers  Regulate body T  Influence formation of blood clots Derived from omega-3 and omega-6 essential fatty acids