Changes

** DNA intercalating agents (e.g. [[ethidium bromide]])

** DNA intercalating agents (e.g. [[ethidium bromide]])

** [[DNA crosslinker]] (e.g. [[platinum]])

** [[DNA crosslinker]] (e.g. [[platinum]])

** Oxidative damage caused by [[oxygen]](O)] [[Radical (Chemistry)|radical]]s

** Oxidative damage caused by [[oxygen]](O) [[Radical (Chemistry)|radical]]s

* Radiation

* Radiation

** [[Ultraviolet]] radiation (nonionizing radiation) - excites electrons to a higher energy level. DNA absorbs one form, ultraviolet light. Two nucleotide bases in DNA - cytosine and thymine-are most vulnerable to excitation that can change base-pairing properties. UV light can induce adjacent thymine bases in a DNA strand to pair with each other, as a bulky dimer.  

** [[Ultraviolet]] radiation (nonionizing radiation) - excites electrons to a higher energy level. DNA absorbs one form, ultraviolet light. Two nucleotide bases in DNA - cytosine and thymine-are most vulnerable to excitation that can change base-pairing properties. UV light can induce adjacent thymine bases in a DNA strand to pair with each other, as a bulky dimer.  

==Beneficial mutations==

==Beneficial mutations==

A very small percentage of all mutations actually have a positive effect. These mutations lead to new versions of proteins that help an organism and its future generations better adapt to changes in their environment. For example, a specific 32 base pair deletion in human CCR5 (CCR5-32) confers [[HIV]] resistance to [[Zygosity|homozygotes]] and delays [[AIDS]] onset in [[Zygosity|heterozygotes]].<ref>[http://www.cdc.gov/genomics/hugenet/factsheets/FS_CCR5.htm]</ref> The CCR5 mutation is more common in those of European descent. One theory for the [[etiology]] of the relatively high frequency of CCR5-32 in the European population is that it conferred resistance to the [[bubonic plague]] in mid-14th century Europe.<ref>[http://www.pbs.org/wnet/secrets/case_plague/clues.html]</ref>

A very small percentage of all mutations actually have a positive effect. These mutations lead to new versions of proteins that help an organism and its future generations better adapt to changes in their environment. For example, a specific 32 base pair deletion in human CCR5 (CCR5-32) confers [[HIV]] resistance to [[Zygosity|homozygotes]] and delays [[AIDS]] onset in [[Zygosity|heterozygotes]].<ref>[https://www.cdc.gov/genomics/hugenet/factsheets/FS_CCR5.htm]</ref> The CCR5 mutation is more common in those of European descent. One theory for the [[etiology]] of the relatively high frequency of CCR5-32 in the European population is that it conferred resistance to the [[bubonic plague]] in mid-14th century Europe.<ref>[https://www.pbs.org/wnet/secrets/case_plague/clues.html]</ref>

==References==

==References==

* Taggart R. Starr C. ''Biology The Unity and Diversity of Life: Mutated Genes and Their Protein Products''.  14.4:227. Thompson Brooks/Cole 2006.

* Taggart R. Starr C. ''Biology The Unity and Diversity of Life: Mutated Genes and Their Protein Products''.  14.4:227. Thompson Brooks/Cole 2006.

===Online books===

===Online books===

* Chapter 7, [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Search&db=books&doptcmdl=GenBookHL&term=mutation+AND+mga%5Bbook%5D+AND+110363%5Buid%5D&rid=mga.section.996 The Molecular Basis of Mutation] in ''Modern Genetic Analysis'' by Anthony J. F. Griffiths, William M. Gelbart, Jeffrey H. Miller and [[Richard Lewontin|Richard C. Lewontin]] (1999) published by W. H. Freeman and Company ISBN 0-7167-3597-0.

* Chapter 7, [https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Search&db=books&doptcmdl=GenBookHL&term=mutation+AND+mga%5Bbook%5D+AND+110363%5Buid%5D&rid=mga.section.996 The Molecular Basis of Mutation] in ''Modern Genetic Analysis'' by Anthony J. F. Griffiths, William M. Gelbart, Jeffrey H. Miller and [[Richard Lewontin|Richard C. Lewontin]] (1999) published by W. H. Freeman and Company ISBN 0-7167-3597-0.

* Chapter 9, [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=hmg.section.1050 Instability of the human genome: mutation and DNA repair] in ''Human Molecular Genetics 2'' by Tom Strachan and  Andrew P. Read (1999) published by John Wiley & Sons, Inc.

* Chapter 9, [https://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=hmg.section.1050 Instability of the human genome: mutation and DNA repair] in ''Human Molecular Genetics 2'' by Tom Strachan and  Andrew P. Read (1999) published by John Wiley & Sons, Inc.

* ''[http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=gnd.preface.91 Genes and Disease]'' from the [[National Library of Medicine]] provides descriptions of mutations that cause human diseases. For example, a common mutation associated with [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Search&db=books&doptcmdl=GenBookHL&term=mutation+AND+gnd%5Bbook%5D+AND+138070%5Buid%5D&rid=gnd.section.207 Huntington disease] is an increased number of copies of repeated CGA triplets in the [[Huntingtin]] gene.

* ''[https://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=gnd.preface.91 Genes and Disease]'' from the [[National Library of Medicine]] provides descriptions of mutations that cause human diseases. For example, a common mutation associated with [https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Search&db=books&doptcmdl=GenBookHL&term=mutation+AND+gnd%5Bbook%5D+AND+138070%5Buid%5D&rid=gnd.section.207 Huntington disease] is an increased number of copies of repeated CGA triplets in the [[Huntingtin]] gene.

* ''[http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=gene GeneReviews]'' by Roberta A. Pagon, Editor-in-chief is made available by the [[University of Washington]] and contains peer-reviewed descriptions of heritable diseases written by experts. For example, [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=gene.chapter.brca1 BRCA1 and BRCA2 Hereditary Breast/Ovarian Cancer] describes mutations in [[BRCA1]] and [[BRCA2]] that are associated with  predispositions to cancer.

* ''[https://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=gene GeneReviews]'' by Roberta A. Pagon, Editor-in-chief is made available by the [[University of Washington]] and contains peer-reviewed descriptions of heritable diseases written by experts. For example, [https://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=gene.chapter.brca1 BRCA1 and BRCA2 Hereditary Breast/Ovarian Cancer] describes mutations in [[BRCA1]] and [[BRCA2]] that are associated with  predispositions to cancer.

==External links==

==External links==