Which statement defines a mutation?

Which statement defines a mutation?

• A. A non-heritable change in phenotype due to environmental factors.
• B. A change in the DNA sequence that is not inherited.
• C. A chromosomal rearrangement occurring during meiosis.
• D. A heritable change in the DNA sequence that can alter a gene's function.

Answer: (D)

Mutations are heritable changes in the DNA sequence that can alter a gene's function. This means a change in the nucleotide sequence can affect the amino acid sequence of a protein or the way a gene is regulated, and if it occurs in germ cells, it can be passed to offspring. Environmental influences that change an organism’s phenotype without changing the DNA sequence are not mutations in the genetic sense. A chromosomal rearrangement involves a structural change, which can affect inheritance, but it isn’t the classic definition of a mutation as a sequence change that can be inherited. So, the statement that best defines a mutation is the one describing a heritable DNA sequence change that can alter a gene's function.

Mutations are heritable changes in the DNA sequence that can alter a gene's function. This means a change in the nucleotide sequence can affect the amino acid sequence of a protein or the way a gene is regulated, and if it occurs in germ cells, it can be passed to offspring. Environmental influences that change an organism’s phenotype without changing the DNA sequence are not mutations in the genetic sense. A chromosomal rearrangement involves a structural change, which can affect inheritance, but it isn’t the classic definition of a mutation as a sequence change that can be inherited. So, the statement that best defines a mutation is the one describing a heritable DNA sequence change that can alter a gene's function.