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प्रश्न
Amino acids show amphoteric behaviour. Why?
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उत्तर
In aqueous solution, the carboxyl group of an amino acid can lose a proton and the amino group can accept a proton to give a dipolar ion known as zwitterion.
\[\begin{array}{cc}
\ce{\phantom{........}O\phantom{.......................................}O}\\
\phantom{.......}||\phantom{.......................................}||\\
\ce{R - CH - C - O - H ⇌ R - CH - C - O^-}\\
\phantom{.......}|\phantom{........................................}|\\
\ce{\phantom{.........}\ce{\text{}^\bullet_\bullet}NH2\phantom{................................}^+NH3}
\end{array}\]
Therefore, in its zwitterionic form, the amino acid can act as both an acid and a base.
\[\begin{array}{cc}
\ce{\phantom{........}O\phantom{....................................}O\phantom{.................................}O}\\
\phantom{.......}||\phantom{....................................}||\phantom{.................................}||\\
\ce{R - CH - C - O^- ⇌[H+][OH-] R - CH - C - O^- ⇌ R - CH - C - OH}\\
\phantom{.......}|\phantom{.....................................}|\phantom{...................................}|\\
\ce{\phantom{............}NH2\phantom{.............................}^+NH3\phantom{............................}^+NH3}
\end{array}\]
Thus, amino acids show amphoteric behaviour.
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संबंधित प्रश्न
What are amino acids?
Differentiable between the following:
Essential amino acids Non-essential amino acids
Match the following:
| I | II |
| (i) Amino acids | (A) protein |
| (ii) Thymine | (B) Nucleic acid |
| (iii) Insulin | (C) DNA |
| (iv) phosphodiester linkage | (D) Zwitter ion |
Which of the following is the best matched options?
Each polypeptide in a protein has amino acids linked with each other in a specific sequence. This sequence of amino acids is said to be ______.
Lysine, \[\begin{array}{cc}
\ce{H2N - (CH2)4 - CH - COOH}\\
\phantom{.....}|\\
\phantom{........}\ce{NH2}
\end{array}\] is:
(i) α-Amino acid
(ii) Basic amino acid
(iii) Amino acid synthesised in body
(iv) β-Amino acid
Amino acids can be classified as α–, β–, γ–, δ– and so on depending upon the relative position of amino group with respect to carboxyl group. Which type of amino acids form polypetide chain in proteins?
Which of the following compound can form a zwitterion?
The amino acid are the end product of the digestion of:-
Which of the following is a basic amino acid?
Define Zwitter ion
