BIOLOGY
AMINO ACIDS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Amino acid side chain.
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Amino group attached to the
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Carboxyl group attached to the
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Hydrogen atom attached to the
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Detailed explanation-1: -At a pH inferior to their pK, the lysine, arginine and histidine side chains accept an H+ ion (proton) and are positive charged.
Detailed explanation-2: -Finally, there are 3 polar basic amino acids, which contain an ammonium group in the R group and carry a positive charge at physiological pH. An example of this class of amino acid is lysine.
Detailed explanation-3: -If you decrease the pH by adding an acid to a solution of an amino acid, the-COO-part of the zwitterion picks up a hydrogen ion. This time, during electrophoresis, the amino acid would move towards the cathode (the negative electrode).
Detailed explanation-4: -Lysine and arginine are the two positively charged amino acids in proteins that have high aqueous pKa’s ( 10.5 for Lys1 and 13.8 for Arg2) indicating a strong propensity to carry charge at physiological pH.