What are the basic constituents of the cell membrane?

The cell membrane is produced of lipids, proteins and carbohydrates.

The membrane lipids are phospholipids, a special type of lipid to which one extremity a phosphate group is bound therefore assigning electrical charge to this region of the molecule. As phospholipids have one electrically charged extremity and a long neutral organic chain they can organize themselves in two layers of associated molecules: the hydrophilic portion (polar) of each layer faces outwards in contact with water (a polar molecule too) of the extracellular and the intracellular space and the hydrophobic chains (non polar) face inwards isolated from the water. Because this type of membrane is made of two phospolipid layers it is also known as a bilipid membrane.