Membrane proteins are classify as either integral (intrinsic) or peripheral (extrinsic) depending on how tightly they are linked with membrane. The Integral membrane proteins are strongly bound to the membrane by interactions with the hydrophobic core of the bilayer and can be extracted from them only by using agents which disrupt the membrane structure, such as organic solvents like as chloroform or detergents. Many integral proteins contain one or more regions of the polypeptide chain which span the lipid bilayer and interact noncovalently with the hydrophobic fatty acid chains. Furthermore, some are anchored in the membrane by a covalently attached fatty acid or hydrocarbon chain.