question_answer 20)

  One of the following is true with respect to AUG (a) it codes for methionine only (b) it is also an initiation codon (c)it codes for methionine in both prokaryotes and eukaryotes (d) All of the above

Answer:

                  (d) Polypeptide synthesis is signaled by two initiation codons commonly AUG or methionine codon and rarely GUG or valine codon. Since there are 64 triplet codons and only 20 amino acids, the incorporation of some amino acids must be influenced by more than one codon. Only tryptophan (UGG) and methionine (AUG) are specified by single codons. AUG codes for methioninein both prokaryotes and eukaryotes.