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COURSE BIOMOLECULES Lesson Fatty Acids Dr. Praveen Kumar Agrawal
Fatty acids Fatty acids are the basic components of neutral fats and phospholipids. Fatty acids are simple organic acids, containing long hydrocarbon chain, which may be straight or ringed. Fatty acids in natural fats are usually straight chain derivatives. They contain an even number of carbon atoms, because they are synthesised from 2 carbon units. Common number of carbon atoms is 16 to 24 The carboxylic end of fatty acid is polar (hydrophilic water loving) while hydrocarbon tail is non-polar (hydrophobic). The polar ends face toward water and form a monolayer over it and reduce surface tension
Essential fatty acids . Plants can synthesise all naturally occurring fatty acids but animals can synthesize only a few. Animals can not synthesise Linoleic acid, linolenic acid and arachidonic acid. Animals therefore must include these acids in their diet. Hence these three fatty acids are called essential fatty acids. . These are present chiefly in the oils of sunflower, groundnut. Deficiency of these acids produces phrenoderma (follicular hyperkeratosis), in which skin of the person is severely affected. Saturated and unsaturated fatty acids Saturated fatty acids are those which do not have any double bonds in the hydrocarbon chain. . While unsaturated fatty acids have one or more double or triple bonds in their hydrocarbon chains. Single double bonded fatty acids are called monounsaturated fatty acids while those having two or more double bonds are called polyunsaturated fatty acids.
Palmitic acid Stearic acid Oleic acid Linoleic acid Linolenic acid CH3 (CH214COOH CH3(CH2h6COOH CH3 (CH2CH CH(CH2)7COOH CH3(CH24CH CHCH2CH CH(CH2)COOH
Saturated fatty acids Unsaturated Fatty acids These do not have any double / triple bonds in their These have double / triple bonds in their hydrocarbon hydrocarbon chain These are straight chain Solid at room temperature Have high melting point These can increase blood cholesterol These are abundant in animal fats Hydrogenation does not alter their structure Examples- Palmitic acid, Stearic acid chain These have a bent at double bond Liquid at room temperature Have low melting point These lower the blood cholesterol Mainly found in plant fats Change to saturated fatty acids on hydrogenation Examples-Oleic acid, Linoleic acid, Arachidonic acid and Linolenic acid
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