Nonpolar (Molecular Biology)

A molecule or group of atoms is said to be nonpolar if it lacks electronegative atoms such as N, O, and S, so that it does not contain groups with substantial partial electrostatic charges. Such molecules include steroids and other lipids, and the long hydrocarbon side-chains of amino acids such as leucine, isoleucine, and valine. Such molecules show a tendency to move from water to oily surroundings such as the interiors of membranes. The physical basis of this tendency, and its quantitative measurement, are discussed in Hydrophobicity and Hydrophobic Effect.