All cells have a cell membrane, also known as a plasma membrane, which separates the interior of the cell from the external environment.
A semipermeable lipid bilayer makes up the cell membrane.
The movement of materials into and out of the cell is controlled by the cell membrane.
Glycerophospholipids, molecules formed of glycerol, a phosphate group, and two fatty acid chains, are the primary component of most cellular membranes, including plasma membranes and interior membranes.