What you’ll learn to do: Recognize the impact of DNA mutations

A mutation is a permanent alteration in the DNA sequence that makes up a gene; that is, the sequence differs from what is found in most people. Mutations range in size; they can affect anywhere from a single DNA building block (base pair) to a large segment of a chromosome that includes multiple genes. Gene mutations can be classified in two major ways:

• Hereditary mutations are inherited from a parent and are present throughout a person’s life in virtually every cell in the body.
• Acquired (or somatic) mutations occur at some time during a person’s life and are present only in certain cells, not in every cell in the body.

Mutations can impact an organism in both negative and positive ways—and sometimes a genetic mutation doesn’t impact the organism at all!