What is a mutation in genetics?

A mutation in genetics refers to an alteration in the inherited nucleic acid sequence. This change can occur in various forms, such as a substitution of one nucleotide for another, the addition or deletion of nucleotides, or larger structural changes in chromosomes. Mutations can arise from several factors, including errors during DNA replication, exposure to radiation, or chemical agents. These alterations can lead to new traits that may be beneficial, neutral, or harmful to the organism, and they are essential for evolution as they contribute to genetic variability within a population.

The other choices do not accurately describe a mutation. An unchanging genetic structure implies that there is no variation or alteration, which contradicts the very nature of mutations. Identical traits passed down refer to the concept of inherited features that remain the same and do not account for the changes that mutations introduce. A fixed genetic trait also suggests stability and lack of alteration, which is not characteristic of mutations. Understanding these distinctions highlights the dynamic nature of genetic information and the role mutations play in the evolution of species.