A frameshift mutation could result from which of the following genetic changes?

• A. A point mutation that changes a codon into a stop codon (nonsense mutation)
• B. A base substitution in a promoter that reduces transcription without changing the reading frame
• C. A single base substitution that changes one codon to another codon
• D. Insertion of a single nucleotide into the coding sequence of a gene

Answer: (D)

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. Review the types of mutations listed: a nonsense mutation changes a codon to a stop codon but does not shift the reading frame; a base substitution in a promoter affects transcription but not the coding sequence; a single base substitution changes one codon but keeps the reading frame intact.
3. Recognize that only insertions or deletions of nucleotides (indels) that are not multiples of three cause frameshift mutations because they alter the grouping of nucleotides into codons downstream of the mutation.
4. Identify that the insertion of a single nucleotide into the coding sequence changes the reading frame from that point forward, leading to a frameshift mutation.
5. Conclude that among the options, the insertion of a single nucleotide into the coding sequence is the genetic change that results in a frameshift mutation.