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.
However, these mistakes are rare, and the cell has repair mechanisms that can repair some damage. - Sometimes a permanent change occurs in a cell's DNA and this is called a mutation. - Because a mutation in a gene causes a change in the protein that is made, the enzyme is nonfunctional. Types of mutations - Mutations can range from changes in a single base pair in the coding sequence of DNA to the deletions of large pieces of chromosomes. - Point mutations involve a chemical change in just one base pair and can be enough to cause a genetic disorder. - A point mutation in which one base is exchanged for another is called a substitution. - Most substitutions are missense mutations, where the DNA code is altered so that it codes for the wrong amino acid. - Other substitutions, called nonsense mutations, change the codon for an amino acid to a stop codon. Nonsense mutations cause translation to terminate early. Nearly all nonsense mutations lead to proteins that cannot function normally. - Another type of mutation that can occur involves the gain or loss of a nucleotide in the DNA sequence.