(a) These must be supplied to our diet as are not synthesized in body.
(b) Some of them are
(1) Valine (2) Leucine (3) Isoelucine (4) Phenylalanine (5) Arganine (5) Threonine
(6) Tryptophan (7) Methionine (8) Lysine (9) Arginine (10) Histadine
Note: Histidine and arginine are essential i.e. can be syntrhesized but not in quantities sufficient to permit normal growth.
Non – Essential Amino acids
These amino acids are synthesized in body.
Some of them are
These are as follows:
(1) Glycine (2) Alanine (3) Tyrosine (4) Serine (5) Cystine (6) Proline (7) Hydroxyprocine
(8) Cysteine (9) Aspartic acid (10) Glutonic acid
Synthesis of a – amino acids
Protein can be hydrolyzed by refluxing with dilute hydrochloric acid to give a mixture of α – amino acids. The resulting mixture can be separated by
(a) fractional crystallization.
(b) Fractional distillation of their ester followed by hydrolysis (Fischer’s method)
(c) Selective precipitation as salt with phosphotungstic and picric acid.
(d) Distribution of amino acid between n – butanol saturated with water (Dakin’s method).
(e) Column, paper and gas chromatography.
By amination of α – halo acid
By Gabriel synthesis
By Strecker Synthesis
Note: Generally the aldehyde is treated with a mixture of ammonium chloride and potassium cyanide in aqueous solution.
(D) All are correct
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