Presentation on theme: "Chapter 15 Lipids 15.3 Waxes, Fats, and Oils"— Presentation transcript:
1 Chapter 15 Lipids 15.3 Waxes, Fats, and Oils Waxes are esters of long-chain alcohols and fatty acids.
2 WaxesWaxes areesters of saturated fatty acids and long-chain alcoholscoatings that prevent loss of water by leaves of plants
3 Fats and Oils: Triacylglycerols Fats and oils arealso called triacylglycerolsesters of glycerolproduced by esterificationformed when the hydroxyl groups of glycerol react with the carboxyl groups of fatty acids
4 TriacylglycerolsIn a triacylglycerol, glycerol forms ester bonds with three fatty acids.
5 Formation of a Triacylglycerol In a triacylglycerol, three hydroxyl groups on a glycerol molecule form ester bonds with the carboxyl groups of three fatty acids.
6 TriacylglycerolsTriacylglycerol may contain different fatty acids.
7 Learning CheckWhat are the fatty acids in the following triacylglycerol?
8 Solution What are the fatty acids in the following triacylglycerol? Stearic acidOleic acidMyristic acid
9 Melting Points of Fats and Oils A fatis usually solid at room temperatureis prevalent in meats, whole milk, butter, and cheeseAn oilis usually liquid at room temperatureis prevalent in plants such as olive and safflower
10 Oils with Unsaturated Fatty Acids have more unsaturated fatshave cis double bonds that cause “kinks” in the fatty acid chainswith “kinks” in the chains do not allow the triacylglycerol molecules to pack closelyhave lower melting points than saturated fatty acidsare liquids at room temperature
11 Diagram of Triacylglycerol with Unsaturated Fatty Acids Unsaturated fatty acid chains with kinks cannot pack closely.
12 Percent Saturated and Unsaturated Fatty Acids in Fats and Oils Vegetable oils have low melting points because they have a higher percentage of unsaturated fatty acids than do animal fats.
13 Learning Check Draw the condensed structural formula of glyceryl trilinoleate (trilinolein).
14 Solution Draw the condensed structural formula of glyceryl trilinoleate (trilinolein).