Fatty acids have four main biological roles:

1.  They are used to create sphingolipids and glycerophospholipids which are necessary elements of biological membranes;

2.  Numerous proteins are covalently modified by fatty acids. palmitate   (C16:0)   and Myristate   (C14:0)     are   straightly   attached   to   some proteins, thus phosphatidylinositol is covalently connected to the C terminus of other proteins by a complex glycosylated structure;

3.  Fatty acids act as fuel molecules,   being collected as triacylglycerols and broken down to make energy;

4.  Derivatives of fatty acids serve as hormones (like as the prostaglandins) and intracellular second messengers (like as DAG and IP3).