The electron microscope has revealed that the cell membrane is composed of layers of

A lipid bi-layer and intergral proteins.

The lipid bi-layer is formed when the two phospholipid layers are placed together with the hydrophobic layers (made of fatty acids) face each other, and the hydrophilic parts (composed of phosphate heads) face outside.

Intergral protein of cell membrane may transverse the cell membrane (transverse protein) as IMP involved in active transport of substance across the cell.