Both lipids and carbohydrates are important in animal cells because both are found in structures of the cell. The cell membrane is made up of glycerophospholipids which are molecules composed of glycerol. a phosphate group and two fatty acid chains. Glycerol is a three- carbon - molecule that functions as the backbone of the membrane lipids Carbohydrates are found in cell receptors where they are combined with protein to form glycoprotein that make up the structures of the receptors. Receptors can be found on the cell membrane.