Question of the Week: What Causes a Gene To Mutate or Change?
Submitted by Virginia Salazar, Whittier, Calif. Answered by Dr. Paul Sternberg, Professor of Biology, Caltech In most cases, the sequence of DNA making up a gene is copied accurately when a cell divides. This accurate process ensures that each cell is like its parent cell. DNA consists of a string of DNA bases, the letters in the genetic alphabet. The bad news is that DNA is under continual attack by chemicals within the cell that are byproducts of the ordinary workings of each cell; by environmental hazards; by radiation; and by the general tendency for things to break down. Environmental hazards include natural plant products as well as human-made chemicals. These attacks result in a range of problems, ranging from changes of a single DNA letter to a break in the string. The good news is that cells counter these continual attacks by correcting essentially all the damage, using a host of beautiful molecular machines. But a mutation occurs when a cell fails to repair damage to its DNA,
