Another real Q's on MCAT!

[jbag]

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If a protein has a head group is non polar and the tail group is polar, then is it
a) hydrophilic
b) hydrophilic
c) amphoteric
d) Polar

 

[Sm00th13]

•••quote:•••Originally posted by jbag:
•If a protein has a head group is non polar and the tail group is polar, then is it
a) hydrophilic
b) hydrophilic
c) amphoteric
d) Polar•••••I think you might have read this question wrong because the thing that has a head group and a tail group are phosphorlipid from the bilayer membrane. I never heard of proteins having a head group and/or a tail group. Maybe a transverse transmembrane protein sticking from the cystoplasm side and extracellular side. Besides, There's not a lot of inform. given for this question. Then again, maybe it can be amphipathic.

 

[jbag]

No, actually, that was the exact Q's; I too was perplexed why they reversed it.

 

[Sm00th13]

Well it could be amphipathic or it could be a MCAT error (which does occur) on AAMC's part. I say it's an MCAT error. choice D should have at least been amphipathic (e.g. having hydrophobic and hydrophillic properties). 😎 😎

 

[Alli Cat]

I agree with choice d) polar. Amphoteric refers to a molecule that has acidic and basic properties; the Q didn't address this. I bet a lot of people picked it because it sounds like "amphipathic." I believe that proteins can have polarity in terms of hydrophobicity, which you talk about in terms of micelles and inclusion bodies... anyone else?

 

[Sm00th13]

•••quote:•••Originally posted by Alli Cat:
•I agree with choice d) polar. Amphoteric refers to a molecule that has acidic and basic properties; the Q didn't address this. I bet a lot of people picked it because it sounds like "amphipathic." I believe that proteins can have polarity in terms of hydrophobicity, which you talk about in terms of micelles and inclusion bodies... anyone else?•••••It's not the terms of polar or nonpolar that the problem. It's the uses of "head groups" and "tail groups", e.g. how is it define on a protein. It could be define based on the spatial location of the protein in bilayer membrane. Or it could be based on the the percentage of polar to nonpolar; or vice versa.

 

[CamelJockey]

I had that question too. And now looking at it with more "time", I see thats another I missed...great... <img border="0" title="" alt="[Eek!]" src="eek.gif" />