Lipids

LIPIDS: Roles in the body energy storage, insulation protection of organs, steroid hormones, structural components of cells

Health Effects Too many Too few The right/wrong kind Obesity, heart disease Too few Body can’t make important hormones Dry skin and hair The right/wrong kind Too much LDL or trans fats: increased heart disease More HDL: decrease risk for heart disease

Classification Simple Lipids / Triglycerides Fats and oils: esters of fatty acids and glycerol Waxes: esters of high molar-mass fatty acids and high molar-mass alcohols Compound lipids / Phospholipids yield glycerol, phosphoric acid, fatty acids Lecithin: common name for phospholipids, isolated from animals (eggs), common non-toxic emulsifying agent used as food additive Steroids: 17-Carbon structure of 4 fused rings Misc: fat soluble vitamins (A, D, E, K)

Fatty Acids Long carbon chains with carboxylic acid groups Long carbon chain makes them mostly non-polar (hydrophobic/fatty) Saturated fats: no double bond, pack together easily, solid at room temp Unsaturated fats: presence of a double bond cis or trans Natural: cis, because of kink, can’t pack together, low dispersion forces, liquid at room temp Synthetic: trans

Mono-unsaturated (MUFA) vs poly-unsaturated (PUFA) Oleic acid: mono-unsaturated omega carbon (omega is the last letter of Greek alphabet) Alpha carbon linoleic acid: poly-unsaturated Omega-6 fatty acid Double bond occurs 6 carbons away from omega carbon = linolenic acid: poly-unsaturated Omega-3 fatty acid Double bond occurs 3 carbons away from omega carbon =

Essential fatty acids (EFAs) Some fatty acids are precursors to important biological molecules, but cannot be synthesized in the body: Omega-3 and 6 fatty acids are like this. Omega-3 is important for brain growth and development reduce inflammation and help prevent risk factors associated with chronic diseases such as heart disease, cancer, and arthritis. omega-3 fatty acid deficiency include extreme tiredness (fatigue), poor memory, dry skin, heart problems, mood swings or depression, and poor circulation found in fish, such as salmon, tuna, and halibut, other marine life such as algae and krill, certain plants (including purslane), and nut oils Omega-6 fatty acids are linked with inflammation and other health problems Parts taken from University of Maryland Medical Center website http://www.umm.edu/altmed/articles/omega-3-000316.htm (4/16/09)

Determining Degree of Saturation Alkene + Iodine  Addition reaction with color change Iodine Number: The mass of iodine that is absorbed by 100 g of substance Number of iodine molecules that add to an unsaturated fat can distinguish between saturated, mono and poly unsaturated fats Reacts with 1 molecule of iodine Reacts with 2 molecules of iodine

3.2 g of iodine reacts with 0.01 moles of a fatty acid, how many double bonds does it have? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Fats and Oils Triglyceride (Triglycerol) Ester linkages formed from carboxylic acid of fatty acid and alcohol from glycerol Glycerol: 3 OH groups (hence, triglyceride) 3 R groups usually different Most have 14-18 Carbons

Fats provide more than 2x the energy that carbs do when oxidized to CO2 and water. Carbs and Protein: 4 kcal/g Fats: 9 kcal/g Carbon atoms in fats are more reduced (not bonded to O) than those of most other food

Digestion of Fats Enzyme Catalyzed Hydrolysis Lipase Opposite of esterification/condensation, requires H2O Products: 3 fatty acids, and glycerol Happens in a step-wise fashion (one fatty acid lost at a time) + 3 fatty acids Glycerol

Saponification

Phospholipids One of the fatty acid chains on the triglyceride is changed to a phosphate group. Phosphate like carboxylic acid, COOH, Makes a phosphate ester

Phospholipids polar end (phosphate) Non-polar end (fatty acids) Forms phospholipid bilayer (liposome / cell membrane)

Cell Membrane Fluidity (animation) Semipermeable Keep bad stuff out, but let good stuff in

Steroids Lipids w/ four fused rings Cholesterol – a steroid with an alcohol Use in body (on red book cd) Cholesterol

Cholesterol Progesterone Estrogen Testosterone

Hormone Uses Sex Hormone Prod-uction Role Other Androgen (testosterone) Testes Development and maintenance of male reproductive system Estrogen (estradiol) Ovaries Same as above for females Progestin (Progesterone) Prepare and maintain uterus, help developing embryo

HDL vs LDL HDL: high density lipoprotein (45-55% P) LDL: low density lipoprotein (20-25% P) Different proportions of protein and lipid Protein = water soluble, lipid = not Blood mostly water, LPs needed to transport cholesterol through the body HDL: Prevent build up of cholesterol in arteries can absorb more cholesterol per molecule and can carry it away from arteries, LDL: Carry cholesterol to build and repair damaged tissue which accumulates on damaged tissue LDLs deposit cholesterol in artery walls, causing hardening (plaque) = cardiovascular disease