THE BEECHMONT CREST GUIDE TO BIOLOGICAL TERMS
MUTATION
Mutation is a permanent change that occurs in a cell when its DNA is altered. Mutations often result from exposure to certain environmental factors, such as UV light or chemicals.
Most mutations have negative consequences for the cell. However, some mutations do affect the cell positively, making it more capable of surviving (and therefore reproducing in its environment). An example of a positive mutation is the resistance that many bacteria have developed to antibiotics such as penicillin in recent decades.
There are two types of mutations that can occur in cells: spontaneous mutations and induced mutations.
A spontaneous mutation occurs when a cell divides as a result of an uncorrected mistake by DNA polymerase III.
What do we mean by a “DNA polymerase III mistake”? DNA polymerase is the enzyme that synthesizes new DNA strands. Sometimes the enzyme inserts the wrong nucleotide into a DNA chain that it is copying prior to cell division. Most of these mistakes are caught and corrected---but the enzyme misses some of them.
An induced mutation is an error that occurs as a result of a mutagen. A mutagen is a factor that increases the error rate of DNA polymerase III.
Examples of functional groups: