Question

A nonsense mutation CANNOT be reversed by hydroxylamine exposure. This is because:

A. Hydroxylamine will convert the codon to a different amino acid.
B. Hydroxylamine removes an amino group from the nucleotide.
C. Hydroxylamine can only induce a CG-to-TA transition.
D. Hydroxylamine can only induce a TA-to-CG transition.
E. Both A and C are correct.

Answer 1

Hydroxylamine cannot reverse a nonsense mutation because it can only induce a CG-to-TA transition, which does not correct a stop codon to an amino acid codon.

Step-by-step explanation:

A nonsense mutation changes an amino acid codon into a stop codon, leading to premature termination of protein synthesis, which usually yields a nonfunctional protein. The exposure to hydroxylamine cannot reverse a nonsense mutation because hydroxylamine can only induce a CG-to-TA transition. Such a transition mutation does not correct the stop codon back to an amino acid codon, which means a hydroxylamine-induced change wouldn't fix the premature stop and restore the original or a comparable amino acid to rescue protein function. Therefore, the correct answer is E. Both A and C are correct.