Which mutation disrupts the reading frame by insertion or deletion not in multiples of three?

Which mutation disrupts the reading frame by insertion or deletion not in multiples of three?

• A. Silent mutation
• B. Missense mutation
• C. Frameshift mutation
• D. Nonsense mutation

Answer: (C)

Reading frame is read in consecutive triplets, so the grouping of nucleotides into codons matters for every amino acid produced. If you insert or delete nucleotides but not in multiples of three, the downstream grouping shifts. This changes every codon from that point onward, typically producing a string of incorrect amino acids and often a premature stop codon. That misalignment is what defines a frameshift mutation. Insertion or deletion of three nucleotides preserves the frame, so the downstream codons stay aligned and you mainly alter the protein by adding or removing whole amino acids rather than scrambling the entire sequence. Other mutation types either don’t change an amino acid at all (silent), swap one amino acid for another without shifting the frame (missense), or introduce a stop codon without shifting the reading frame (nonsense). The crucial idea is that non-multiple-of-three indels disrupt the reading frame and drastically change the protein.

Reading frame is read in consecutive triplets, so the grouping of nucleotides into codons matters for every amino acid produced. If you insert or delete nucleotides but not in multiples of three, the downstream grouping shifts. This changes every codon from that point onward, typically producing a string of incorrect amino acids and often a premature stop codon. That misalignment is what defines a frameshift mutation. Insertion or deletion of three nucleotides preserves the frame, so the downstream codons stay aligned and you mainly alter the protein by adding or removing whole amino acids rather than scrambling the entire sequence. Other mutation types either don’t change an amino acid at all (silent), swap one amino acid for another without shifting the frame (missense), or introduce a stop codon without shifting the reading frame (nonsense). The crucial idea is that non-multiple-of-three indels disrupt the reading frame and drastically change the protein.