what macromolecule makes up the cell membrane?

The cell membrane is primarily made of a lipid bilayer composed of phospholipids, with cholesterol, and a variety of proteins embedded in or associated with the membrane. Carbohydrate groups are often attached to lipids or proteins on the exterior surface, forming glycoproteins and glycolipids. In short, the key macromolecules are phospholipids (forming the bilayer), proteins (integral and peripheral), cholesterol (a lipid that modulates fluidity), and carbohydrates (glycoproteins and glycolipids).