Which of the following processes yields arachidonicacid in mammals?
|A||Elongation of stearic acid|
|B||Chain elongation and one desaturation of linolenic acid|
|C||Chain elongation and two desaturations of linoleic acid|
|D||Desaturation of oleic acid|
a. In mammals, arachidonic 5, 8,11, 15- eicosapentaenoic acid acid can only be synthesized from essential fatty acids derived from the diet. Linoleic 9, 12-octadecadienoic acid produces arachidonic acid following two desaturations and chain elongation.
b. Although linolenic 9,12,1 5-octadecatrienoic acid also is an essential fatty acid, desaturation and elongation produce 8,11,14,1 7-eicosatetraenoic acid, which is distinct from arachidonic acid.
c. Oleic, palmitic, and stearic acids are all nonessential fatty acids that cannot give rise to arachidonic acids in mammals.