Must have precise anticodon specificity to match codon information in the mRNA Must be recognized by correct aminoacyl-tRNA synthetase so they are activated with correct amino acid Must recognize and bind correct ribosomal sites to perform their function as adaptors. Reduce the cysteine amino acid component of cysteyl-tRNA cys to alanine. Alanine was incorporated into polypeptides at positions that should have been occupied by cysteine. Even though the cysteine codons in the mRNA, and the corresponding cysteine anticodons in the tRNA were all normal and intact, alanine was still incorporated into the polypeptide. This proves that the tRNA, rather than the amino acid itself, is responsible for codon recognition specificity and subsequent amino acid incorporation into a growing polypeptide chain.
Initiation includes all events preceding formation of the first peptide bond.
The S-D sequence base pairs with a specific ribosomal RNA sequence to correctly position the mRNA molecule within the initiation complex so initiation at the appropriate AUG codon can occur.