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Membrane transport

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Membrane transport

Postby grant01 » Thu Dec 02, 2010 10:04 pm

a. Explain why the isomers d-pentose and l-pentose have such varied permeabilities although nearly the same structure.
b. Explain what relationship is shown with urea, thiourea and dimethyl urea.
c. Explain why glycerol has a low permeability but can be the backbone of the membrane triglycerides.

I think
a) Due to same molecular weight and different atom spacial arragement d-pentose and l-pentose have such varied permeabilities. Is this right?

b) In above chart the urea, thiourea, and dimethyl urea are in sigmiodal fashion and has same basic chemical structure. urea is most soluable in water and thiourea is not really soluable in water, and dimethyl urea is a big compound and they are polar molecule. thiourea is slightly polar?

c) glycerol has low permeability b/c it as three hydrophilic group that makes it water soulable and glycerol is backbone because it is central for all fatty acid know as triglycerides?

I'm sorry if my asnwer don't make sense, I'm really having trouble with this class.
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Postby jwalin » Sun Dec 05, 2010 12:56 am

a) yes its because of the different spatial arrangement. its basically because there must be a channel protien most probably and the other isomer cant activate because of its different arrangement. its like if u have a palm sensor or sth that basically checks the hand layout of lets say the left hand you cant put your right hand on it.

c) basically the hydroxyl groups get replaced and the high hydrophilicity is lost and hence the triglycerides can make up the membrane for they are completely nonpolar (though be careful though to not confuse triglycerides with phospholipids which usually make up for most of the membrane.)
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Postby JackBean » Wed Dec 08, 2010 12:31 pm

a) you didn't answer why is that. You said, because of the different arrangement, what is already stated in the question, so I guess that's not supposed to be the answer...

b) hard to say, as we do not know what chart are you talking about...

c) basically as jwalin said

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