Multiple Choice
Which type of mutation most directly causes translation of an mRNA to stop prematurely by creating a stop codon within the coding sequence?
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17. Mutation, Repair, and Recombination
Types of Mutations
Multiple Choice
Which of the following DNA mutations would most likely result in a frameshift mutation in a protein-coding region?
A
Substitution of one nucleotide for another within a codon
B
Insertion of one nucleotide into the coding sequence
C
Deletion of three nucleotides from the coding sequence
D
A point mutation that changes a codon to a stop codon (nonsense mutation)
Verified step by step guidance1
Understand what a frameshift mutation is: it occurs when nucleotides are inserted or deleted from the DNA sequence in numbers not divisible by three, which shifts the reading frame of the codons during translation.
Recall that codons are read in groups of three nucleotides, so any insertion or deletion that is not a multiple of three will change how the sequence is read downstream, potentially altering every amino acid after the mutation.
Analyze each option: a substitution changes one nucleotide but does not shift the reading frame; deletion of three nucleotides removes one codon but keeps the reading frame intact; a nonsense mutation changes a codon to a stop codon but does not shift the frame.
Identify that insertion of one nucleotide adds an extra base, which is not divisible by three, thus shifting the reading frame and causing a frameshift mutation.
Conclude that among the options, the insertion of one nucleotide into the coding sequence is the mutation most likely to cause a frameshift.
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