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amino acids, methionine?

Discussion in 'MCAT Study Question Q&A' started by MikeMitchell, Jul 28, 2011.

  1. MikeMitchell

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    I have been using the mnemonic VIP MALT pH glycine to remember the non-polar or hydrophobic amino acids. VIP MALT ph glycine came from examkrackers and Ive also seen GAVLIMP (or something similar, dont know where the trytophan went on that one) used as well on other websites.

    Kaplan has methionine listed as a polar amino acid, which it sure as hell looks like with a carboxylic acid and amine group. Whats the deal?

    Thanks!
     
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  3. user003

    user003 lab slave

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    Methionine is def nonpolar, I don't know what Kaplan is thinking
     
  4. MikeMitchell

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    [​IMG]

    This is nonpolar?
     
  5. ih2183

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    Def. nonpolar. Just because there is a slight polarity towards the sulfur atom, doesn't make the entirety of the side chain polar. The hydrocarbon chain makes the side group greasy, and overall, the side chain will tend to associate with other greasy residues.
     
  6. ih2183

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    The amine and carboxylic part are quenched when polymerized, so in a polypeptide chain, the residue is always considered. Otherwise to really ascertain the net polarity of the molecule in and of itself, one needs to add the dipole vectors of each electronegative atom.
     
  7. MikeMitchell

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    Thanks for the detailed response. Huge Kaplan fail on that one.
     

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