Question

How many amino acids will be coded by the mRNA sequence – 5'CCCUCAUAGUCA¹UAC3' if a adenosine residue is inserted after 12^th nucleotide?
(1) Five amino acids (b) Six amino acids (c) Two amino acids (d) Three amino acids

Answer 1

Dear student,
Answer is c) two amino acids.
The sequence provided by you does not have a start codon AUG and for the process of translation to start ribosome must find the start codon. Lets assume that translation process has started. Addition of an adenosine after 12th nucleotide will not make any difference as the third codon is UAG which is the stop codon and the process of translation would cease. As bases are read in triplets and 1 triplet codes for an amino acid, only two amino acids would be coded by this sequence.

Regards