Straight chain fatty acids are the basic building block in the universe of lipids. They are composed of a carboxylic acid with a long and unbranched chain of carbon atoms. The number of carbons in the fatty acid varies among species. In higher organisms like mammals, fatty acids always consist of an even number of carbons, however in lower organisms like bacteria, odd number of carbon also exists. Most naturally occurring fatty acids have 4 to 26 carbons, but longer fatty acids of up to 35 carbons are also described in literature.