Plymouth Elementary School first grade students celebrate the groundbreaking of the new Legoland Discovery Center at Plymouth Meeting Mall by playing in a pile of more than 50,000 Lego bricks spilled by a dump truck at the Oct. 25 ceremony. | Photo courtesy Legoland Discovery Center.
If this DNA has a mutation, the child that grows from the fertilized egg will have the mutation in each of his or her cells. Acquired (or somatic) mutations occur at some time during a personâs life and are present only in certain cells, not in every cell in the body.
A mutation is a change in a DNA sequence that alters the protein for which the DNA codes. Sometimes mutations occur due to damage from an outside source, such as ultraviolet radiation. Excess ultraviolet radiation from the sun sometimes causes mutations that lead a cell to become cancerous. Most mutations that damage a DNA strand are harmful. Other mutations occur due to deletion or insertion of DNA base pairs. One such deletion in humans confers HIV resistance or a delayed AIDS onset. Humans who are heterozygous for the mutation, meaning they possess one mutant gene and one normal gene, experience a slower progression of AIDS.