Fatty Acids

Fatty acids are straight hydrocarbon-chain organic acids. The number of carbon atoms in the chain varies from 4 to about 24. Because fatty acids are synthesized by extending the chain two carbon atoms at a time, the number of carbon atoms in the chain is usually an even number. In higher organisms, 16 and 18 are the most common.

The molecular structure of an 18-carbon fatty acid.
18-carbon fatty acid