Mutation

From ArticleWorld

Mutation is the result of alterations to the genetic material found in cells. They may be caused by errors in the copying of the genetic information during cell division as well as by viruses, chemicals and deliberate cell processes. There are two main types of mutation in multicellular organisms. These are germline mutations that can be passed down to descendents and somatic mutations that are not inheritable. Mutations are thought to be necessary for the process of evolution as favorable mutations tend to accumulate and unfavorable mutations tend to die out by the process of natural selection. Many mutations are neutral as they have no effect on the organism. Many mutations are also temporary and repaired by DNA repair.

Classification

There are several ways to classify mutations. These include:

• By effect on structure – Structural changes may be small as in cases where only one or a few nucleotides are altered or large-scale mutations in chromosomal structure.
• By effect on function – These include mutations that result in the gain or loss of functions as well as dominant negative mutations and lethal mutations.
• By the phenotype affected – These are morphological mutations and biochemical mutations.
• Special classes – These are conditional mutations that only manifest under certain conditions.

Another classification identifies two major classes of mutations. These are:

• Spontaneous mutations
• Induced mutations

Disease

Mutations may result in non-functional or partially non-functional proteins. If the mutation affects a protein playing a critical role in the cells then medical problems can ensue. These conditions are referred to as genetic disorders. Most mutations however do not cause any medical problems. Problems do arise however in germ cell mutations as these can be transmitted to offspring and result in the development of hereditary diseases.