Question

How many amino acids will be coded by the sequence if the 14${}^{th}$ base of given mRNA, converts to G?
5' AUG UUU CUC UAG CCG 3'

• A. Three
• B. Five
• C. Four
• D. Two

Answer 1

The correct option is A Three

In the given sequence of mRNA,

• First codon is AUG which is the start codon and also codes for methionine.
• Second codon is UUU which codes for phenylalanine.
• Third codon is CUC which codes for leucine.
• Fourth codon is UAG which is the stop codon and does not code for any amino acid.

Now, the translation will terminate at this stop codon and the codons after this stop codon will not be translated as well. So, if the 14${}^{th}$ base of given mRNA converts to G, the codon CCG will become CGG but this will not have any impact on the translated amino acids because translation will terminate at UAG. Hence, only three amino acids will be produced.

So, the correct answer is 'Three'.