Multiple Choice
In the context of types of mutations, what most directly causes a frameshift mutation in a protein-coding region?
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17. Mutation, Repair, and Recombination
Types of Mutations
Multiple Choice
Which of the following is a frameshift mutation?
A
Deletion of a single nucleotide from the coding sequence
B
A nonsense mutation that changes a codon into a stop codon
C
A silent mutation that changes a codon but not the amino acid
D
Substitution of one nucleotide for another nucleotide
Verified step by step guidance1
Understand what a frameshift mutation is: it occurs when nucleotides are inserted or deleted from the coding sequence in numbers not divisible by three, causing a shift in the reading frame of the codons during translation.
Review each option and determine if it changes the reading frame: a deletion of a single nucleotide removes one base, which is not divisible by three, so it shifts the reading frame.
Recognize that a nonsense mutation changes a codon to a stop codon but does not shift the reading frame; it simply truncates the protein.
Note that a silent mutation changes a codon without altering the amino acid sequence, so it does not affect the reading frame.
Understand that substitution of one nucleotide for another (a point mutation) changes one base but does not shift the reading frame since the number of nucleotides remains the same.
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