In this article, fatty acids will be identified by their chain length, the number of double bonds present, and the position of the first double bond from the methyl end of the molecule. Thus 14:0 denotes a saturated fatty acid with 14 carbon atoms, 16:1n-9 denotes a monounsaturated fatty acid with 16 carbon atoms in which one double bond occurs nine carbon atoms from the methyl end, and 20:4n-6 denotes a polyunsaturated fatty acid with 20 carbon atoms in which the first of four double bonds is found six carbon atoms from the methyl end. Unless otherwise noted, all double bonds are in the cis configuration and double bonds in polyunsaturated fatty acids are separated by a single methylene (-CH2-) group. The carboxyl carbon atom of any fatty acid is carbon-1. The adjacent carbon atom is referred to as either carbon-2 or the a-carbon; the next is carbon-3 or the ^-carbon, and so on. Some examples are shown in Figure 1.
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