The circle part of the structure is the CARBOXYL PART.
Generally, lipids are naturally occurring molecules and they serve as sources of high energy value in humans. Basically, lipids are synthesized from glycerol and fatty acids. The number of fatty acids attached to the glycerol determine the type of lipid that the molecule is. The glycerol is a type of alcohol and is made up of hydroxyl ions. lipid bio molecules are soluble in non polar solvent and insoluble in water.
