The genetic information stored in DNA is "decoded" to form proteins via the process of translation. This involves the formation of peptide bonds between amino acids bound to transfer RNA (tRNA) molecules that glide over the ribosome in very close proximity to each other, and elongate the peptide chain, which later undergoes conformational change, forming a protein. In contrast to the codon-dependent aminoacyl-tRNA recognition in the small ribosomal subunit, the peptide bond formation in question occurs at the peptidyl transferase center (PTC) of the large ribosomal subunit, in a non-amino acid specific manner. This non-specificity indicates that the large subunit evolved before the small subunit, which has more specific interactions with mRNA and tRNA.