Each moiety may contain additional functional groups, for example, methyl para-hydroxybenzoate contains a phenol functional group within the acyl moiety.
From the en.wikipedia.org
Liu's group also made some interesting observations about gene expression and gene location in their study of the acyl-modifying enzyme genes.
From the sciencedaily.com
The acyl chains in the fatty acids are extended by a cycle of reactions that add the actyl group, reduce it to an alcohol, dehydrate it to an alkene group and then reduce it again to an alkane group.