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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.


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Re: Urea and membrane permeability of RBC

... the concentration of urea on the two sides of the membrane is the same (facilitated diffusion). But now the osmolarity of the intracellular solution is higher than the osmolarity ...

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by kidprof
Thu Aug 08, 2013 8:18 pm
 
Forum: Cell Biology
Topic: Urea and membrane permeability of RBC
Replies: 2
Views: 33127

In and out cell help

... help them as in active transport? Do they move freely as in simple diffusion or do they use only restricted place to pass as in facilitated diffusion?

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by JackBean
Thu Nov 08, 2012 7:19 pm
 
Forum: General Discussion
Topic: In and out cell help
Replies: 1
Views: 1702

In and out cell help

... the theatre, which transport process does this most resemble (simple diffusion, facilitated diffusion, or active transport) AND WHY? 2) An hour later, the same theatre is ...

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by japjis
Sat Oct 27, 2012 6:50 am
 
Forum: General Discussion
Topic: In and out cell help
Replies: 1
Views: 1702

Facilitated Diffusion vs Diffusion

What is facilitated diffusion? I can't find a place that explains it so I can understand it. I have to compare facilitated diffusion ...

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by luvinpurple
Thu Oct 04, 2012 5:58 am
 
Forum: Cell Biology
Topic: Facilitated Diffusion vs Diffusion
Replies: 1
Views: 4184

Need help with Plasma Membrane

... but in small proportions and in form of mucopolysacchides etc. types of diffusion, simple diffusion is where substances pass through the phospholipid layer, and facilitated diffusion is when it passes through the proteins. yes, its true. osmosis is ...

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by shubham999
Mon Mar 19, 2012 5:32 am
 
Forum: Cell Biology
Topic: Need help with Plasma Membrane
Replies: 4
Views: 7628
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