Sterols Structure 4 rings with side chains Cholesterol

Sterols § Structure: 4 rings with side chains § Cholesterol: not found in plants or plant foods § No calories – not an energy source § Precursor of steroids: testosterone, estrogen, progesterone and vitamin D § Source: liver (not essential) and animal products – eggs, meat and dairy products § Too much harmful: forms deposits in arteries arteriosclerosis heart attack and strokes

Phospholipids § Structure: glycerol with 2 fatty acids, and phosphate group with a nitrogenous base attached §Lecithin: nitrogenous base is choline § Soluble in water & fat § Part of cell membrane – allows fat soluble vits and hormones to enter and leave easily § No calories – not an energy source § Source: liver (not essential) § Emulsifer in blood (bound to proteins) and foods (eggs, lecithin)

Characteristics of Lipids Triglyceride Sterol Phospholipid Structure Glycerol with 3 fatty acid chains (saturated or unsaturated) attached 4 ring structure with side chains attached Glycerol with 2 fatty acid chains and 1 phosphate and nitrogenous based attached Supplies Energy Essential Yes (9 kcal/gm) Yes – omega 6 (linoleic acid) and omega 3 (linolenic acid) No No Soluble in H 2 O No No Functions Cushion and protection of vital organs Insulation flavor and palatability of food satiety (feeling of fullness) No – made in liver; found No - made in liver in dairy products and eggs Yes Precursor of steroids: testosterone, estrogen, progesterone and vitamin D Heavy steroid use can lead to fatty deposits in arteries arteriosclerosis heart attack and strokes Part of cell membrane – allows fat soluble vits and hormones to enter and leave easily Emulsifer in blood (bound to proteins) and foods (eggs, lecithin)