Cell Membrane

Cell Membrane medical illustration
Body cells are surrounded by a thin covering called the plasma (cell) membrane. The cell membrane is composed of two layers of phospholipid molecules (the phospholipid bilayer). Within this layer are the plasma proteins. The integral proteins serve as channels through which substances are selectively transported into and out of a cell. When bound to chains of oligosaccharides the integral proteins also serve as receptor sites. Peripheral proteins are loosely bound to the membrane surface. Also present are cholesterol molecules and glycolipids.