Which genetic change would most likely result in a frameshift mutation within a coding sequence?

• A. A silent point mutation that does not change the amino acid sequence
• B. A missense point mutation that changes one codon to another codon
• C. Insertion of a single nucleotide (not in multiples of 3) into the coding region
• D. Deletion of exactly three nucleotides from the coding region

Answer: (C)

Verified step by step guidance

1. Understand what a frameshift mutation is: it occurs when nucleotides are inserted or deleted from the coding sequence in numbers not divisible by three, which shifts the reading frame of the codons during translation.
2. Recall that codons are read in groups of three nucleotides, so any insertion or deletion that is not a multiple of three will change the grouping of all downstream codons, potentially altering every amino acid after the mutation.
3. Analyze each option: a silent point mutation changes a single nucleotide but does not alter the amino acid sequence, so it does not cause a frameshift.
4. A missense point mutation changes one codon to another but involves only one nucleotide substitution, so it does not shift the reading frame.
5. An insertion or deletion of nucleotides in multiples of three adds or removes whole codons, preserving the reading frame, but an insertion of a single nucleotide (not a multiple of three) disrupts the reading frame, causing a frameshift mutation.