Question

There is only one possible sequence of amino acids when deduced from a given set of nucleotides. But multiple nucleotide sequences can be deduced from a single amino acid sequence. Explain this phenomenon.

Answer 1

Some amino acids are coded by more than one codon (known as degeneracy of codons), hence on deducing a nucleotide sequence from an amino acid sequence, multiple nucleotide sequence will be obtained.For e.g., Ile has three codons: AUU, AUC AUA hence dipeptide Met–Ile can have the following nucleotide sequence: 
(i) AUG – AUU 
(ii) AUG – AUC 
(iii) AUG – AUA

and if, we deduce amino acid sequence the above nucleotide sequences all the three will code for Met–Ile