Multiple Choice
In the context of types of mutations, a mutation in DNA would initially start with a change in which molecule?
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17. Mutation, Repair, and Recombination
Types of Mutations
Multiple Choice
In the context of types of mutations, what most directly causes a frameshift mutation in a protein-coding region?
A
A substitution that changes a codon but still codes for the same amino acid due to redundancy in the genetic code (silent mutation)
B
Insertion or deletion of nucleotides in a number not divisible by , shifting the reading frame
C
A base substitution that converts an amino acid codon into a stop codon (nonsense mutation)
D
A single-base substitution that changes one codon into a different codon (missense mutation)
Verified step by step guidance1
Understand that a frameshift mutation occurs when the reading frame of the mRNA is altered during translation, which changes how codons are read downstream of the mutation.
Recall that codons are read in groups of three nucleotides, so any insertion or deletion (indel) of nucleotides that is not a multiple of three will shift the reading frame.
Recognize that a substitution mutation (silent, missense, or nonsense) changes one or more nucleotides but does not shift the reading frame because the number of nucleotides remains the same.
Identify that only insertions or deletions of nucleotides in numbers not divisible by three cause the ribosome to read incorrect triplets, leading to a frameshift mutation.
Conclude that the most direct cause of a frameshift mutation is an insertion or deletion of nucleotides in a number not divisible by 3, which shifts the reading frame and alters the downstream amino acid sequence.
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