ABSTRACT
Overview Ribosomes exist normally as separate subunits that come together to form a ribosome when they bind to an mRNA near its 5¢ end. The ribosome reads the nucleotide sequence from the 5¢ to 3¢ direction, synthesizing the corresponding protein from amino acids in an N-terminal (amino terminal) to C-terminal (carboxyl terminal) direction. The amino acids used are covalently bound to tRNA (transfer RNA) molecules to form aminoacyltRNAs. Each aminoacyl-tRNA bears a triplet of bases, called an anticodon. The ribosome reads each triplet codon of the mRNA in turn and an aminoacyl-tRNA molecule with an anticodon that is complementary to the codon binds to it via hydrogen bonding. A peptide bond is then formed between the incoming amino acid and the growing end of the polypeptide chain.
