文档介绍：03 基因突变 Gene Mutation
Gene Mutation
Change in genes caused by change in structure of the DNA.
Base(s) in DNA is (are) changed to other(s), or a base(s) is (are) added or removed.
Rearrangements of the chromosomes occur and are also considered.
Mutations are heritable changes in ic material.
1. Mutagens or Mutagenic Agents
These are substances, conditions and forms that significantly increase the frequency of mutations.
Mutations can occur at a spontaneous rate, or a far greater rate when there is exposure to mutagenic agents.
Exposure to too high a level of mutagens can threaten the survival of a species; ., frog species in the states of Washington and Oregon are facing extinction. This appears to be caused by reduced atmospheric ozone, and the resulting increased level of ultraviolet radiation.
A forms of energy
Examples of a forms of energy are ultraviolet light, x-rays, cosmic energy, gamma radiation, alpha particles, beta particles and neutrons.
Ultraviolet (UV) light
UV light has shorter wavelengths than visible light. Though these waves are invisible to the human eye, some insects, like bumblebees, can see them!
Scientists have divided the ultraviolet part of the spectrum into three regions: the near ultraviolet, the far ultraviolet, and the extreme ultraviolet.