How do salts&sugars get through the membrane?

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wiggleandawalk
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How do salts&sugars get through the membrane?

Post by wiggleandawalk » Thu Nov 23, 2006 1:33 pm

Hey,
Im pretty new to this, so any help would be great!
I have got an assignment to do and im having difficulty with these two questions;-

why do salts and sugars have difficulty getting through the membrane?

How is it possible for salts and sugars to pass through the membrane?

Have the answers got anything to do with sugars/salts being to big to move through the membrane's pores...... help me out plaese

wiggle

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MrMistery
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Post by MrMistery » Thu Nov 23, 2006 6:03 pm

look up water solubility and the terms hidrophobic/hidrophilic in relation with the membrane and salts&sugars.

for the second one, look up selective permeability.

this info can easily be found in any textbook, on this site's tutorials or on the internet using a search engine(google, yahoo etc)
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theman
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Post by theman » Thu Nov 23, 2006 10:57 pm

SOME MOLECULES DO NOT CROSS CELL MEMBRANES EASILY, SUCH AS SUGARS AND SALTS AND HAVE TO BE HELPED ACROSS:

Larger, polar uncharged molecules (e.g., glucose + salts) will not easily pass through the phospholipid bilayer. All ions, even small ones (e.g., Na+, H+) are hydrophilic and therefore have difficulty penetrating the hydrophobic layer.

Transport proteins: TO HELP SOME MOLECULES ACROSS. Transport proteins allow a way for hydrophilic substances to avoid (bypass) the hydrophobic core of the bilayer. Transport proteins thus make biological membranes permeable to specific ions and certain polar molecules of moderate size. - ie sugars and salts!

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Dr.Stein
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Post by Dr.Stein » Fri Nov 24, 2006 4:31 am

the size of molecules, the solubility ---> facilitated transportation: protein carrier, protein canal, etc.
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