Changes

[[File:lighterstill.jpg]][[File:Lung-cancer-cells.jpg|right|frame]]

[[File:lighterstill.jpg]][[File:Lung-cancer-cells.jpg|right|frame]]

*Date: [http://www.wikipedia.org/wiki/14th_Century 14th century]

*Date: [https://www.wikipedia.org/wiki/14th_Century 14th century]

==Definitions==

==Definitions==

*1 : a significant and basic alteration : [[change]]

*1 : a significant and basic alteration : [[change]]

:b : an [[individual]], strain, or trait resulting from mutation

:b : an [[individual]], strain, or trait resulting from mutation

==Description==

==Description==

'''Mutations''' are changes in the [[DNA]] [[sequence]] of a [[cell]]'s genome and are caused by [[radiation]], [[virus]]es, [http://en.wikipedia.org/wiki/Transposon transposons] and mutagenic [[chemicals]], as well as errors that occur during [http://en.wikipedia.org/wiki/Meiosis meiosis] or DNA replication. They can also be induced by the [[organism]] itself, by cellular processes such as [http://en.wikipedia.org/wiki/Somatic_hypermutation hypermutation].

'''Mutations''' are changes in the [[DNA]] [[sequence]] of a [[cell]]'s genome and are caused by [[radiation]], [[virus]]es, [https://en.wikipedia.org/wiki/Transposon transposons] and mutagenic [[chemicals]], as well as errors that occur during [https://en.wikipedia.org/wiki/Meiosis meiosis] or DNA replication. They can also be induced by the [[organism]] itself, by cellular processes such as [https://en.wikipedia.org/wiki/Somatic_hypermutation hypermutation].

Mutation can result in several [[different]] types of [[change]] in [[DNA]] sequences; these can either have no [[effect]], alter the product of a gene, or prevent the gene from [[functioning]] properly or completely. Studies in the fly [http://en.wikipedia.org/wiki/Drosophila_melanogaster Drosophila melanogaster] suggest that if a mutation changes a [[protein]] produced by a gene, this will probably be harmful, with about 70 percent of these mutations having damaging [[effects]], and the remainder being either neutral or weakly beneficial. Due to the damaging effects that mutations can have on [[cells]], [[organisms]] have evolved [[mechanisms]] such as DNA repair to remove mutations. Therefore, the optimal mutation [[rate]] for a [[species]] is a trade-off between costs of a high mutation rate, such as deleterious mutations, and the [[metabolic]] costs of maintaining systems to reduce the mutation rate, such as [http://en.wikipedia.org/wiki/DNA_repair DNA repair] enzymes. [[Viruses]] that use [http://en.wikipedia.org/wiki/RNA RNA] as their genetic material have rapid mutation rates, which can be an advantage since these [[viruses]] will evolve constantly and rapidly, and thus evade the defensive [[responses]] of e.g. the [[human]] [[immune]] system.[http://en.wikipedia.org/wiki/Mutation]

Mutation can result in several [[different]] types of [[change]] in [[DNA]] sequences; these can either have no [[effect]], alter the product of a gene, or prevent the gene from [[functioning]] properly or completely. Studies in the fly [https://en.wikipedia.org/wiki/Drosophila_melanogaster Drosophila melanogaster] suggest that if a mutation changes a [[protein]] produced by a gene, this will probably be harmful, with about 70 percent of these mutations having damaging [[effects]], and the remainder being either neutral or weakly beneficial. Due to the damaging effects that mutations can have on [[cells]], [[organisms]] have evolved [[mechanisms]] such as DNA repair to remove mutations. Therefore, the optimal mutation [[rate]] for a [[species]] is a trade-off between costs of a high mutation rate, such as deleterious mutations, and the [[metabolic]] costs of maintaining systems to reduce the mutation rate, such as [https://en.wikipedia.org/wiki/DNA_repair DNA repair] enzymes. [[Viruses]] that use [https://en.wikipedia.org/wiki/RNA RNA] as their genetic material have rapid mutation rates, which can be an advantage since these [[viruses]] will evolve constantly and rapidly, and thus evade the defensive [[responses]] of e.g. the [[human]] [[immune]] system.[https://en.wikipedia.org/wiki/Mutation]

[[Category: Biology]]

[[Category: Biology]]