Facilitated diffusion

Definition

noun

Transport of substances across a biological membrane from an area of higher concentration to an area of lower concentration by means of a carrier molecule. Since the substances move along the direction of their concentration gradients, energy is not required.


Supplement

For example, polar molecules and charged ions dissolved in water can not diffuse freely across cell membrane due to its hydrophobic lipids. They can only be transported across membranes by proteins forming transmembrane channels. Larger molecules are transported by transmembrane carrier proteins, such as permeases that change their conformation as the molecules are carried through, for example glucose or amino acids.


Also called: facilitated transport.
Compare: active transport.
See also: passive transport, diffusion, carrier protein.


Please contribute to this project, if you have more information about this term feel free to edit this page



This page was last modified on 28 October 2008, at 10:51. This page has been accessed 280,088 times. 
What links here | Related changes | Permanent link