lipids

• Found in plant and animal (except cholesterol because cholesterol is only made in livers)
• Major functions: lipid membranes, precursor for steroid hormones (estrogen, testosterone, cortisol), energy storage, lubrication
• Essential lipids: linoleic (n-6) and alpha-linoleic (n-3). Essential because we lack enzyme to make double bonds past the 9 position
• Triacylglycerol (TAG): most abundant dietary lipid
• Saturated: 0 double bonds
• Monounsaturated: 1 double bond
• Polyunsaturated: 2 or more double bonds
• Stearic acid: saturated, Oleic acid: monounsaturated, Linoleic acid: polyunsaturated
• Cis bonds: H on same side, kinks are introduced
• Trans bonds: H on opposite sides, straight chain is maintained
• Phospholipids are the second most abundant in the diet
• Phospholipid: glycerol backbone, 2 fatty acids, and a polar head group
• Sphingolipid: sphingosine (amino alcohol) + fatty acid'
• Ceramide: sphingosine + fatty acyl moiety
• Sphingomyelin: ceramide + phosphocholine
• Signaling molecules are primarily on the cytosolic side of the cell membrane
• CCK stimulates pancreas and gallbladder to initiate digestion. EEC cells start this release
• Bile acids emulsify fats into lipid droplets: cholesterol and phospholipids