Multiple Choice
In genetics, what best describes a missense mutation?
44
views
17. Mutation, Repair, and Recombination
Types of Mutations
Multiple Choice
Which of the following is an example of a frameshift mutation?
A
A three-nucleotide deletion that removes one amino acid but preserves the reading frame (in-frame deletion)
B
A base substitution that creates a premature stop codon (nonsense mutation)
C
Insertion of one nucleotide into a coding sequence, shifting the reading frame downstream
D
A point mutation that changes one codon but does not shift the reading frame (missense 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, causing a shift in the reading frame during translation.
Recognize that the genetic code is read in triplets (codons), so adding or removing nucleotides in multiples of three preserves the reading frame, while other changes disrupt it.
Analyze each option to see if it changes the reading frame: an in-frame deletion removes three nucleotides, so it does not shift the frame; a nonsense mutation is a base substitution that creates a stop codon but does not shift the frame; a point mutation changing one codon (missense) also does not shift the frame.
Identify that insertion of one nucleotide changes the number of nucleotides by one, which is not divisible by three, thus shifting the reading frame downstream and altering all subsequent codons.
Conclude that the insertion of one nucleotide into a coding sequence is the example of a frameshift mutation because it disrupts the triplet reading frame and can drastically change the resulting protein.
Related Videos
Related Practice
