<prompt> Aminoacyl t-RNA is not require for ?ProlineLysineHydroxylysineMethionine  <response>: Ans. is c i.e., Hydroxylysine The initial step in protein synthesis is the activation of amino acid in which each of the 20 amino-acids is covalently attached to their respective t-RNA, forming specific amino acyl t-RNA.The reaction is catalyzed by aminoacyl t-RNA synthase.Hydroxyproline and hydroxylysine are not represented into genetic code, i.e. they to not have t-RNA capable of accepting them and inseing them into polypeptide chain. Therefore, they have to be synthesized post-translationally from proline and lysine residues in the polypeptides. 