Question

Study the mRNA segment given above which is complete to be translated into a polypeptide chain.

(i) Write the codons ‘a’ and ‘b’.

(ii) What do they code for?

(iii) How is peptide bond formed between two amino acids in the ribosome?

Answer 1

(i) a is AUG

b is UAA/UAG/UGA

(ii) AUG codes for methionine (initiation codon).

UAA/UAG/UGA does not code for any amino acid, i.e., it is a stop or terminating codon.

(iii) There are two sites (P-site and A-site) in the large subunit of ribosome, where subsequent amino acids bind to and thus are close enough to form peptide bond. The ribosome also acts as a catalyst for the formation of peptide bond.