Question

A normal polypeptide includes the following sequence of amino acids(Note:Each amino acid is named by a three-letter abbreviation.)
Iso-Leu-Pro-Val-His-Ser-Thr-Met

After a mutation, the amino acid sequence becomes the following:

Iso-Leu-Pro-Val-Tyr-Arg-Iso-Gly

Which of the following changes to a nitrogenous base in mRNA is most likely to have occured?

a. A cytosine(C) was replaced with uracil(U).
b. A uracil(U) was replaced with a thymine(T)
c. An adenine( A) was removed and not replaced
d. The codon ACU was removed and not replaced

Answer 1

Answer:

C

Explanation:

The mutation seen is most likely due to a frameshift mutation. A nucleotide was added or removed without replacement. This shifted the codon reading sequence by one nucleotide. Therefore the codon downstream of the mutation will code for different amino acids.