Question

Refer the given mRNA segment.


It can be translated completely into a polypeptide. Which of the following codons may correspond with A and B?

• A. A-AUG, GUG; B-UAA, UAG or UGA
• B. A-UAA, UGA; B-AUG, GUG or UAG
• C. A-AUG, UGA; B-GUG, UAA or UGA
• D. A-AUG, GAG; B-UAA, UUU or UGA

Answer 1

The correct option is A A-AUG, GUG; B-UAA, UAG or UGA

The mRNA has information for the synthesis of polypeptide chain in the form of codons.

A represents start codons and B represents stop codons.

The start codon in the beginning initiates the process of protein synthesis. The start codons are AUG in both prokaryotes and eukaryotes and GUG in certain prokaryotes. The start codons are present at 5' end of mRNA.

The synthesis of polypeptide chain terminates with the help of stop codons. The stop codons are UAG, UGA, UAA. The stop codons are present at 3' end of mRNA.