lecture 26 - This sea lion has a heavy layer of fat Lipids...

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Lipids Lipids Chapter 26 ± This sea This sea lion has a lion has a heavy layer heavy layer of fat of fat Lipids ± Lipids: Lipids: a heterogeneous class of naturally occurring organic compounds classified together on the basis of common solubility properties they are insoluble in water but soluble in aprotic organic solvents, including diethyl ether, methylene chloride, and acetone Lipids Lipids ± Lipids include triglycerides, phospholipids, prostaglandins, prostacyclins, and fat -soluble vitamins, cholesterol, steroid hormones, and bile acids Triglycerides (Fats & Oils) (Fats & Oils) ± Triglyceride: Triglyceride: an ester of glycerol with three fatty acids Fatty Acids Fatty Acids ± Fatty acid: Fatty acid: a carboxylic acid derived from hydrolysis of animal fats, vegetable oils, or membrane phospholipids nearly all have an even number of carbon atoms, most between 12 and 20, in an unbranched chain the three most abundant are palmitic (16:0), stearic acid (18:0), and oleic acid (18:1)
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Fatty Acids Fatty Acids - unsaturated fatty acids have lower melting points than their saturated counterparts; the greater the degree of unsaturation, the lower the melting point in most unsaturated fatty acids, the cis isomer predominates; the trans isomer is rare Unsaturated Fatty Acids Saturat ed Fat ty Acids 20:4 18:3 18:2 18:1 16:1 20:0 18:0 16:0 14:0 12:0 Carbon Atoms/ Double Bonds* Melting Point (°C) Common Name -49 -11 -5 16 1 77 70 63 58 44 Arachidonic acid Linolenic acid Linoleic acid Oleic acid Palmitoleic acid Arachidic acid Stearic acid Palmitic acid Myristic acid Lauric acid Triglycerides example: a triglyceride derived from one molecule each of palmitic acid, oleic acid, and stearic acid, the three most abundant fatty acids in the biological world CH 2 OC(CH 2 ) 14 3 2 OC(CH 2 ) 16 3 3 (CH 2 ) 7 CH=CH(CH 2 ) 7 COCH O O O oleate (18:1) stearate (18:0) palmitate (16:0) Tristearin: a saturated triglyceride A polyunsaturated triglyceride Triglycerides Triglycerides ± Physical properties depend on the fatty acid components melting point increases as the number of carbons in its hydrocarbon chains increases and as the number of double bonds decreases
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Triglycerides Triglycerides ± Physical properties depend on the fatty acid components triglycerides rich in unsaturated fatty acids are generally liquid at room temperature and are called oils Triglycerides Triglycerides ± Physical properties depend on the fatty acid components triglycerides rich in saturated fatty acids are generally semisolids or solids at room temperature and are called fats Triglycerides ± The lower melting points of triglycerides rich in unsaturated fatty acids are related to differences in their three-dimensional shape hydrocarbon chains of saturated fatty acids can lie parallel with strong dispersion forces between their chains ; they pack into well- ordered, compact crystalline forms and melt above room temperature Triglycerides Triglycerides because of the cis configuration of the double bonds in unsaturated fatty acids , their
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This note was uploaded on 09/06/2009 for the course CHEM chem 12 AB taught by Professor Valentin during the Spring '09 term at Evergreen Valley.

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lecture 26 - This sea lion has a heavy layer of fat Lipids...

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