Presentation on theme: "Chapter 17: Lipids Lipids are"— Presentation transcript:
1 Chapter 17: Lipids Lipids are Biomolecules that contain fatty acids or a steroid nucleus.Soluble in organic solvents but not in water.Named for the Greek word lipos, which means “fat.”Extracted from cells using organic solvents.
3 Fatty Acid: Long Chain COOH’s The formulas for fatty acids are written asCondensed formulas.Line-bond formulas.For example caprylic acid with 8 carbon atoms.CH3—(CH2)6—COOHCH3—CH2—CH2—CH2—CH2—CH2—CH2—COOH
20 Melting Points of Fats and Oils A triacylglycerol that is a fatIs solid at room temperature.Is prevalent in meats, whole milk, butter, and cheese.A triacylglycerol that is an oilIs liquid at room temperature.Is prevalent in plants such as olive and safflower.
23 Chemical Properties of Triacylglycerols The chemical reactions of triacylglycerols are similarto those of alkenes and esters.In hydrogenation, double bonds in unsaturated fatty acids react with H2 in the presence of a Ni or Pt catalyst.In hydrolysis, ester bonds are split by water in the presence of an acid, a base, or an enzyme.
28 Oxidation of Unsaturated Fats Unsaturated fatty acids oxidize to short-chain aldehydes and short-chain carboxylic acidsExample: Heavy perspiration
29 Cis and Trans Fatty Acids Unsaturated fatty acids can beCis with bulky groups on same side of C=C.CH3─ (CH2)5 (CH2)7─ COOH cisC=CH HTrans have bulky groups on opposite sides of C=C.CH3─ (CH2)5 HC=C transH (CH2)7─ COOH
30 Trans Fatty Acids and Hydrogenation Are formed during hydrogenation when cis double bonds are converted to trans double bonds.In the body behave like saturated fatty acids.Are estimated to make up 2-4% of our total Calories.Are reported in several studies reported to raise LDL-cholesterol (bad) and lower HDL-cholesterol. (good)
31 Foods that contain Trans Fats MilkBreadFried foodsGround beefBaked goodsStick margerine, soft margerineButterCookies, crackersFood Label reads: “Partially hydrogenated oil”
32 Hydrolysis In hydrolysis, Triacylglycerols split into glycerol and three fatty acids.An acid or enzyme catalyst is required.+3+3
33 Saponification and Soap Is the reaction of a fat with a strong base.Splits triacylglycerols into glycerol and the salts of fatty acids.Is the process of forming “soaps” (salts of fatty acids).With KOH gives softer soaps.