KCET 2018 Biology Solved Paper

The sequence of RNA which has a start codon on side and the stop codon on the other and codes for polypeptide is called the translational unit of the mRNA. Some sequences are not translated in the mRNA. They are present before the start codon at the 5′ end and after the stop codon at the 3′-end. They are known as untranslated regions (UTRs). However, they aid efficient translation.