CEOE Biological Sciences Practice Exam

A mutation is a heritable change in the DNA sequence. It can arise because DNA replication isn’t perfect, leaving errors that become permanent if not fixed. It can also occur when mutagens—such as certain chemicals or radiation—damage DNA, causing base changes, breaks, or other alterations. Recombination during meiosis can shuffle genetic material and create new DNA configurations. These changes—substitutions, insertions, deletions, or larger chromosomal rearrangements—can affect a gene’s function or its regulation and may be passed on to offspring if they occur in germ cells.

Other descriptions describe changes that don’t involve altering the DNA sequence itself (environmentally driven changes in cell structure or transient, non-DNA-based changes in gene expression) or changes only at the RNA level, which are not mutations of the DNA.