CBSE Class 12 Chemistry Notes: Biomolecules – Amino Acids

Introduction

(i)   Amino acids are organic compounds of both, an amino group & carboxylic group.

(ii)   They are represented by general formula:

(iii)  These amino acids are very important because they are the building blocks of protein.

(iv)  Protein is the natural polymer moving α – amino acids as monomer.

(v)  With the exceptions of glycine. All the other amino acids have chiral carbon & have two optically active isomers.

(vi)  All naturally occurring amino acids are in L – series in which -NH₂ group on the left and -OH group in the right as L – glyceraldehydes.

Illustration 1.    Which among the following statements are true for glycine?

                        1.   It exists in crystalline form                2.   It is optically active

                        3.   It is soluble in water                         4.   It can form Zwitter ions

                        (A)  1, 2 and 3                                        (B)  1, 2 and 4

                        (C)  1, 3 and 4                                        (D)  2, 3 and 4

Solution: (C) It is ionic so it exists in crystalline form. Because it is ionic so it soluble in water. Because acidic and basic groups are present in the same molecule, so internal salt formation occurs to form dipolar ion NH₃^– ¾ CH₂ – COO^–

 Classification

Amino acid with non – polar side chain 

I.

II

III

IV

V

VI

VII

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