What is mutation?

What is mutation?

• A. A biochemical event causing a change in the DNA sequence
• B. A random change in phenotype
• C. A change in allele frequency within a population
• D. A temporary change in gene expression

Answer: (A)

Mutation is a permanent, heritable alteration in the DNA sequence. It arises from biochemical events that change nucleotides—such as replication errors, chemical damage, or radiation—producing a new allele. This lies at the heart of genetic variation and evolution because it creates new genetic material that can be passed to offspring (if it occurs in germ cells) and acted on by natural selection or drift. The other options describe different things: a change in phenotype without a change in the underlying DNA, a shift in allele frequencies across a population over time, or a temporary, reversible change in gene expression that doesn’t alter the DNA sequence.

Mutation is a permanent, heritable alteration in the DNA sequence. It arises from biochemical events that change nucleotides—such as replication errors, chemical damage, or radiation—producing a new allele. This lies at the heart of genetic variation and evolution because it creates new genetic material that can be passed to offspring (if it occurs in germ cells) and acted on by natural selection or drift. The other options describe different things: a change in phenotype without a change in the underlying DNA, a shift in allele frequencies across a population over time, or a temporary, reversible change in gene expression that doesn’t alter the DNA sequence.