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    ''Explain the relationship between the ionisation of amino acids and pH''
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    (Original post by Flowerrainbow112)
    ''Explain the relationship between the ionisation of amino acids and pH''
    What do you know about the structure of amino acids and is the word "zwitterion" familiar?

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    (Original post by wolfmoon88)
    What do you know about the structure of amino acids and is the word "zwitterion" familiar?

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    i know that the structure of amino acids have a basic structure and consist of an R group, carboxylic group and a.amino group. Also, i know that the word zwitterion relates to either a molecule or ion having differently charged groups. However, i am not sure how to relate it to the question and am confused on how to answer the question
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    Perhaps: at a neutral pH a zwitterion will be formed. This means that the COOH will donate the H to the basic NH2 end of the amino acid (as NH2 has a lone pair) thus forming COO- and NH3+. However, at high pHs, the carboxylic acid groups will remain as be COO- and the NH3+ (from zwitterion form) will have its H+ taken off by one of the hydroxide ions in solution, leading to NH2 groups being formed. However, at a low pH, the zwitterion form will also change, as the negatively charged COO- ion will attract an H+ from soloution, forming COOH, while the NH3+ will remain as NH3+.

    Think that should answer the question - hope it helped!
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    (Original post by Flowerrainbow112)
    i know that the structure of amino acids have a basic structure and consist of an R group, carboxylic group and a.amino group. Also, i know that the word zwitterion relates to either a molecule or ion having differently charged groups. However, i am not sure how to relate it to the question and am confused on how to answer the question
    Okay :erm: bear with me. What happens when you add acid/base to a solution of amino acid? What is shown when electrophoresis is done?

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    i'm not sure but this is the information i found so far
    Acids in their general definition are proton donors
    Bases in their general definition are proton acceptors

    Amines will either be neutral (NH2) or gain a proton (NH3+)
    Carboxylic acids will either be neutral (COOH) or lose a proton (COO-)

    The proton count on each will depend on the acidity of the solution and note that amino acids can only be neutral or zwitterionic (overall neutral but have formal charges across the molecule).
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    (Original post by Flowerrainbow112)
    i'm not sure but this is the information i found so far
    Acids in their general definition are proton donors
    Bases in their general definition are proton acceptors

    Amines will either be neutral (NH2) or gain a proton (NH3+)
    Carboxylic acids will either be neutral (COOH) or lose a proton (COO-)

    The proton count on each will depend on the acidity of the solution and note that amino acids can only be neutral or zwitterionic (overall neutral but have formal charges across the molecule).
    The answer to your question can be seen in what occurs when you shift the pH of an amino acid solution from acidic to alkali. This is why I asked whether you have done electrophoresis before as it elucidates what occurs. At some point, after enough alkali is added to an acidic amino acid solution; the amino acid will no longer have a net positive or negative charge. (No longer in an ionized state) The pH of the amino acid solution at this point is the "isoelectric point". Therefore what is the function of pH?

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    (Original post by wolfmoon88)
    The answer to your question can be seen in what occurs when you shift the pH of an amino acid solution from acidic to alkali. This is why I asked whether you have done electrophoresis before as it elucidates what occurs. At some point, after enough alkali is added to an acidic amino acid solution; the amino acid will no longer have a net positive or negative charge. (No longer in an ionized state) The pH of the amino acid solution at this point is the "isoelectric point". Therefore what is the function of pH?

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    the function of the pH is to effectively measure the hydrogen ions found present in the solution?
 
 
 
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