Amphiphile

From Biology-Online Dictionary | Biology-Online Dictionary

Definition

noun, plural: amphiphiles

A chemical compound containing both hydrophobic and hydrophilic portions


Supplement

Amphiphile is a chemical compound that is made up of hydrophilic and hydrophobic portions. The hydrophilic portion is water-loving. In contrast, the hydrophobic portion tends to repel water. The hydrophobic portion is a lipophilic group and typically a large hydrocarbon moiety. It is nonpolar and therefore would not dissociate into ions in the presence of water. The hydrophilic portion, in turn, may either be charged or uncharged polar functional group. Examples of amphiphiles are bile salts, phospholipids, soaps, detergents, and surfactants. Phospholipids, in particular, are essential component of biological membranes, such as the plasma membrane. The amphiphilic nature of the phospholipids allows the latter to form a phospholipid bilayer. The polar heads of the phospholipids are found on the exterior whereas the nonpolar tails are on the interior of the bilayer. This structural arrangement of phospholipids in the bilayer of plasma membrane is one of the reasons that the latter is selectively permeable (or semipermeable). It means that not all substances are allowed to enter or leave the cell. Certain substances can relatively move with ease across the phospholipid bilayer whereas others would not be able to unless there are transport or carrier proteins to shuttle them across the phospholipid bilayer of the plasma membrane.


Word origin: Greek amphis ("both") + philia ("love")

See also:

Related form(s):

  • amphiphilic (adjective, of or pertaining to an amphiphile)