Amino acids are biomolecules that contain an alpha-carbon (α-C) attached to two functional groups- carboxyl group (-COOH) and amine group (-NH₂), and an organic side chain (-R).
<em>The carboxyl and amine functional groups are common in all amino acids but the </em><u><em>side chain is distinctive to each amino acid.</em></u>
<u><em>Thus the amino acids can be easily classified on the basis of the properties of this organic side chain</em></u>.
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<u>Therefore, the various amino acids have different side chains.</u>
