Facilitated Diffuion question

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thewax
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Facilitated Diffuion question

Post by thewax » Fri Dec 26, 2008 1:29 am

Note: This is not a homework question. This is part of a study effort to prepare for a big upcoming test.

Question: Does Facilitated diffusion require a hydrophilic channel?????????? If so, then how are large hydrophobic (meaning nonpolar) molecules going to diffuse in (because they are large molecules, they cannot use simple diffusion to diffuse through the plasma membrane)??????????

Progress on this question: AP Biology by Deborah Goldberg says that "Facilitated diffusion requires a hydrophilic channel that will passively transport specific substances acros the membrane..." I got really confused here because then how are large hydrophobic (meaning nonpolar) molecules going to diffuse in (because they are large molecules, they cannot use simple diffusion to diffuse through the plasma membrane)?????????? I initially believed that facilitated diffusion had hydrophobic and hydrophilic channels. I searched on the web, but the websites don't really mention anything about whether the channels are hydrophobic or hydrophilic or both.

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MrMistery
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Post by MrMistery » Fri Dec 26, 2008 6:05 pm

well, what kind of molecules do you have in mind?
Generally, the term facilitated diffusion is specifically reserved for hydrophilic channels, but there are other types of protein-assisted membrane passage, such as pumps and permeases. But again, I don't know what you mean by large and hydrophobic molecules. I don't know many of those. And how large are we talking(daltons)?
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thewax
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Post by thewax » Sat Dec 27, 2008 5:12 pm

okay... thanks - so facilitated diffusion does require a hydrophilic channel... :)

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