Practice question

High translational fidelity, error rate about 1 in 10000 codons, depends principally on aminoacyl-tRNA synthetases employing double-sieve and proofreading mechanisms. Initial activation selects amino acids by size and chemistry in synthetic active site, hydrolyzing non-cognate adenylates, while separate editing domains hydrolyze misacylated tRNAs after transfer. Without this upstream editing, ribosome would insert wrong residues despite codon-anticodon correctness. Ribosome contributes kinetic proofreading at decoding, but ultimate assignment of amino acid to anticodon is dictated by synthetase specificity, preserving genetic code integrity universally.