Rank the following one-base point mutations with respect to their likelihood of affecting the structure of the corresponding polypeptide (from most likely to least likely).
1) insertion mutation deep within an intron
2) substitution mutation at the third position of a codon in an exon
3) substitution mutation at the second position of a codon in an exon
4) deletion mutation within the first exon of the gene
A) 1, 2, 3, 4
B) 4, 3, 2, 1
C) 2, 1, 4, 3
D) 3, 1, 4, 2

Question

Quizplus · Accepted Answer

A deletion mutation within the first exon (4) is most likely to affect the polypeptide structure as it can cause a frameshift. A substitution at the second position of a codon (3) is more likely to change the amino acid than at the third position (2), which often results in a silent mutation. An insertion deep within an intron (1) is least likely to affect the polypeptide as introns are non-coding regions.

Rank the Following One-Base Point Mutations with Respect to Their