In biology, and especially in genetics, a mutant is an organism or a new genetic character arising or resulting from an instance of mutation, which is generally an alteration of the DNA sequence of the genome or chromosome of an organism. It is a characteristic that would not be observed naturally in a specimen. The term mutant is also applied to a virus with an alteration in its nucleotide sequence whose genome is in the nuclear genome. The natural occurrence of genetic mutations is integral to the process of evolution. The study of mutants is an integral part of biology; by understanding the effect that a mutation in a gene has, it is possible to establish the normal function of that gene.[2]
Wild-type Physcomitrella and knockout mosses: Deviating phenotypes induced in gene-disruption library transformants. Physcomitrella wild-type and transformed plants were grown on minimal Knop medium to induce differentiation and development of gametophores. For each plant, an overview (upper row, scale bar corresponds to 1 mm) and a close-up (bottom row, scale bar equals 0.5 mm) is shown. A, Haploid wild-type moss plant completely covered with leafy gametophores and close-up of wild-type leaf. B-D, Different Mutants.[1]
Mutants arise by mutations occurring in pre-existing genomes as a result of errors of DNA replication or errors of DNA repair. Errors of replication often involve translesion synthesis by a DNA polymerase when it encounters and bypasses a damaged base in the template strand.[3] A DNA damage is an abnormal chemical structure in DNA, such as a strand break or an oxidized base, whereas a mutation, by contrast, is a change in the sequence of standard base pairs. Errors of repair occur when repair processes inaccurately replace a damaged DNA sequence. The DNA repair process microhomology-mediated end joining is particularly error-prone.[4][5]
Etymology
Although not all mutations have a noticeable phenotypic effect, the common usage of the word "mutant" is generally a pejorative term[citation needed], only used for genetically or phenotypically noticeable mutations.[6] Previously, people used the word "sport" (related to spurt) to refer to abnormal specimens. The scientific usage is broader, referring to any organism differing from the wild type. The word finds its origin in the Latin term mūtant- (stem of mūtāns), which means "to change".[6]
Mutants should not be confused with organisms born with developmental abnormalities, which are caused by errors during morphogenesis. In a developmental abnormality, the DNA of the organism is unchanged and the abnormality cannot be passed on to progeny. Conjoined twins are the result of developmental abnormalities.
Chemicals that cause developmental abnormalities are called teratogens; these may also cause mutations, but their effect on development is not related to mutations. Chemicals that induce mutations are called mutagens. Most mutagens are also considered to be carcinogens.
Epigenetic alterations
Mutations are distinctly different from epigenetic alterations, although they share some common features. Both arise as a chromosomal alteration that can be replicated and passed on to subsequent cell generations. Both, when occurring within a gene, may silence expression of the gene. Whereas mutant cell lineages arise as a change in the sequence of standard bases, epigenetically altered cell lineages retain the sequence of standard bases but have gene sequences with changed levels of expression that can be passed down to subsequent cell generations. Epigenetic alterations include methylation of CpG islands of a gene promoter as well as specific chromatin histone modifications. Faulty repair of chromosomes at sites of DNA damage can give rise both to mutant cell lineages[4] and/or epigenetically altered cell lineages.[7]
^Waters LS, Minesinger BK, Wiltrout ME, D'Souza S, Woodruff RV, Walker GC (March 2009). "Eukaryotic translesion polymerases and their roles and regulation in DNA damage tolerance". Microbiol. Mol. Biol. Rev. 73 (1): 134–54. doi:10.1128/MMBR.00034-08. PMC2650891. PMID 19258535.
^ abMcVey M, Lee SE (November 2008). "MMEJ repair of double-strand breaks (director's cut): deleted sequences and alternative endings". Trends Genet. 24 (11): 529–38. doi:10.1016/j.tig.2008.08.007. PMC5303623. PMID 18809224.
^Truong LN, Li Y, Shi LZ, Hwang PY, He J, Wang H, Razavian N, Berns MW, Wu X (May 2013). "Microhomology-mediated End Joining and Homologous Recombination share the initial end resection step to repair DNA double-strand breaks in mammalian cells". Proc. Natl. Acad. Sci. U.S.A. 110 (19): 7720–5. Bibcode:2013PNAS..110.7720T. doi:10.1073/pnas.1213431110. PMC3651503. PMID 23610439.
^ abMutant. (n.d.). The American Heritage Dictionary of the English Language, Fourth Edition. Retrieved March 05, 2008, from Dictionary.com
^Dabin J, Fortuny A, Polo SE (June 2016). "Epigenome Maintenance in Response to DNA Damage". Mol. Cell. 62 (5): 712–27. doi:10.1016/j.molcel.2016.04.006. PMC5476208. PMID 27259203.
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For other uses see Mutant disambiguation This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Mutant news newspapers books scholar JSTOR August 2017 Learn how and when to remove this template message In biology and especially in genetics a mutant is an organism or a new genetic character arising or resulting from an instance of mutation which is generally an alteration of the DNA sequence of the genome or chromosome of an organism It is a characteristic that would not be observed naturally in a specimen The term mutant is also applied to a virus with an alteration in its nucleotide sequence whose genome is in the nuclear genome The natural occurrence of genetic mutations is integral to the process of evolution The study of mutants is an integral part of biology by understanding the effect that a mutation in a gene has it is possible to establish the normal function of that gene 2 The blue lobster is an example of a mutant Wild type Physcomitrella and knockout mosses Deviating phenotypes induced in gene disruption library transformants Physcomitrella wild type and transformed plants were grown on minimal Knop medium to induce differentiation and development of gametophores For each plant an overview upper row scale bar corresponds to 1 mm and a close up bottom row scale bar equals 0 5 mm is shown A Haploid wild type moss plant completely covered with leafy gametophores and close up of wild type leaf B D Different Mutants 1 Contents 1 Mutants arise by mutation 2 Etymology 3 Epigenetic alterations 4 See also 5 References 6 External linksMutants arise by mutation EditMutants arise by mutations occurring in pre existing genomes as a result of errors of DNA replication or errors of DNA repair Errors of replication often involve translesion synthesis by a DNA polymerase when it encounters and bypasses a damaged base in the template strand 3 A DNA damage is an abnormal chemical structure in DNA such as a strand break or an oxidized base whereas a mutation by contrast is a change in the sequence of standard base pairs Errors of repair occur when repair processes inaccurately replace a damaged DNA sequence The DNA repair process microhomology mediated end joining is particularly error prone 4 5 Etymology EditAlthough not all mutations have a noticeable phenotypic effect the common usage of the word mutant is generally a pejorative term citation needed only used for genetically or phenotypically noticeable mutations 6 Previously people used the word sport related to spurt to refer to abnormal specimens The scientific usage is broader referring to any organism differing from the wild type The word finds its origin in the Latin term mutant stem of mutans which means to change 6 Mutants should not be confused with organisms born with developmental abnormalities which are caused by errors during morphogenesis In a developmental abnormality the DNA of the organism is unchanged and the abnormality cannot be passed on to progeny Conjoined twins are the result of developmental abnormalities Chemicals that cause developmental abnormalities are called teratogens these may also cause mutations but their effect on development is not related to mutations Chemicals that induce mutations are called mutagens Most mutagens are also considered to be carcinogens Epigenetic alterations EditMutations are distinctly different from epigenetic alterations although they share some common features Both arise as a chromosomal alteration that can be replicated and passed on to subsequent cell generations Both when occurring within a gene may silence expression of the gene Whereas mutant cell lineages arise as a change in the sequence of standard bases epigenetically altered cell lineages retain the sequence of standard bases but have gene sequences with changed levels of expression that can be passed down to subsequent cell generations Epigenetic alterations include methylation of CpG islands of a gene promoter as well as specific chromatin histone modifications Faulty repair of chromosomes at sites of DNA damage can give rise both to mutant cell lineages 4 and or epigenetically altered cell lineages 7 See also EditEvolution Genetic engineering Genetically modified organism Mutants in fiction Mutationism Synthetic lethality Synthetic viabilityReferences Edit Egener et al BMC Plant Biology 2002 2 6 doi 10 1186 1471 2229 2 6 Clock Mutants of Drosophila melanogaster Waters LS Minesinger BK Wiltrout ME D Souza S Woodruff RV Walker GC March 2009 Eukaryotic translesion polymerases and their roles and regulation in DNA damage tolerance Microbiol Mol Biol Rev 73 1 134 54 doi 10 1128 MMBR 00034 08 PMC 2650891 PMID 19258535 a b McVey M Lee SE November 2008 MMEJ repair of double strand breaks director s cut deleted sequences and alternative endings Trends Genet 24 11 529 38 doi 10 1016 j tig 2008 08 007 PMC 5303623 PMID 18809224 Truong LN Li Y Shi LZ Hwang PY He J Wang H Razavian N Berns MW Wu X May 2013 Microhomology mediated End Joining and Homologous Recombination share the initial end resection step to repair DNA double strand breaks in mammalian cells Proc Natl Acad Sci U S A 110 19 7720 5 Bibcode 2013PNAS 110 7720T doi 10 1073 pnas 1213431110 PMC 3651503 PMID 23610439 a b Mutant n d The American Heritage Dictionary of the English Language Fourth Edition Retrieved March 05 2008 from Dictionary com Dabin J Fortuny A Polo SE June 2016 Epigenome Maintenance in Response to DNA Damage Mol Cell 62 5 712 27 doi 10 1016 j molcel 2016 04 006 PMC 5476208 PMID 27259203 External links Edit Wikiquote has quotations related to Mutant Antennapedia mutant Retrieved from https en wikipedia org w index php title Mutant amp oldid 1118575228, wikipedia, wiki, book, books, library,
