Question

In a messenger RNA molecule, untranslated regions (UTRs) are present at: 
I. 5' end before start codon 
II. 3' end after stop codon 
III. 3' end before stop codon 
IV. 5'  end after start codon

• A. I & III
• B. II & III
• C. I & II
• D. III & IV

Hint:

UTRs are important regulatory regions of mRNA. The 5\textsuperscript{' } UTR precedes the start codon and helps in ribosome binding, whereas the 3\textsuperscript{' } UTR follows the stop codon and contributes to mRNA stability and translation efficiency. Understanding their location helps in identifying untranslated regions correctly in any mRNA molecule.

Answer 1

The Correct Option is C

Untranslated regions (UTRs) are segments of mRNA that are not translated into protein but play regulatory roles in translation and stability. The 5\textsuperscript{' } UTR is located upstream of the start codon, while the 3\textsuperscript{' } UTR is downstream of the stop codon. Regions within the coding sequence (inside start and stop codons) are translated and do not qualify as UTRs. Hence, the correct UTRs are I (5\textsuperscript{' } before start codon) and II (3\textsuperscript{' } after stop codon).