A frameshift mutation is described as what?

A frameshift mutation is described as what?

• A. Everything is shifted because of a nucleotide addition or deletion, leading to an entirely wrong protein.
• B. Only a single amino acid is changed.
• C. A stop codon is introduced.
• D. No change to the protein.

Answer: (A)

Frameshift mutations happen when nucleotides are inserted or deleted in numbers that are not multiples of three, so the reading frame of codons shifts. Because codons are read in triplets, this shift changes every downstream codon, producing a completely different sequence of amino acids and often a premature stop. That cascade—an entire stretch of the protein being altered after the mutation—explains why the description of “everything is shifted because of a nucleotide addition or deletion, leading to an entirely wrong protein” is the best way to capture what a frameshift does. If the change were in multiples of three, the frame wouldn’t shift, so the effect would be different (an in-frame insertion or deletion rather than a frameshift). A single amino acid change describes a point mutation, not a frameshift, and while a new stop codon can occur after a frameshift, it isn’t the defining feature. No change to the protein is inconsistent with a frameshift.

Frameshift mutations happen when nucleotides are inserted or deleted in numbers that are not multiples of three, so the reading frame of codons shifts. Because codons are read in triplets, this shift changes every downstream codon, producing a completely different sequence of amino acids and often a premature stop. That cascade—an entire stretch of the protein being altered after the mutation—explains why the description of “everything is shifted because of a nucleotide addition or deletion, leading to an entirely wrong protein” is the best way to capture what a frameshift does. If the change were in multiples of three, the frame wouldn’t shift, so the effect would be different (an in-frame insertion or deletion rather than a frameshift). A single amino acid change describes a point mutation, not a frameshift, and while a new stop codon can occur after a frameshift, it isn’t the defining feature. No change to the protein is inconsistent with a frameshift.