BSC 2010C Chapter 2: Bio Notes - Hydrophobic Substances
Document Summary
Hydrophobic substances are the opposite of hydrophilic substances; they are substances that do not readily dissolve in water and are not attracted to it. The term "hydrophobic" comes from the greek words "hydro" meaning water, and "phobos" meaning fear. Hydrophobic substances can be organic or inorganic and can be classified as nonpolar. Nonpolar hydrophobic substances have no net electric charge and do not interact with water molecules through electric dipole moments. Instead, these substances interact with each other through nonpolar covalent bonds, which are formed by the sharing of electrons between atoms that have similar electronegativity. Examples of nonpolar hydrophobic substances include oils, fats, and waxes. In biological systems, hydrophobic substances play an important role in the formation of biological membranes. Biological membranes are composed of a double layer of phospholipids, which have a hydrophilic head and a hydrophobic tail. The hydrophobic tails are nonpolar and interact with each other to form a stable, water-repelling layer.
