Characterstics and Structure of Gene
17
1/15/2015 Gene Wikipedia, the free encyclopedia http://en.wikipedia.org/wiki/Gene 1/17 This stylistic diagram shows a gene in relation to the double helix structure of DNA and to a chromosome (right). The chromosome is X shaped because it is dividing. Introns are regions often found in eukaryote genes that are removed in the splicing process (after the DNA is transcribed into RNA): Only the exons encode the protein. The diagram labels a region of only 55 or so bases as a gene. In reality, most genes are hundreds of times longer. Gene From Wikipedia, the free encyclopedia A gene is the molecular unit of heredity of a living organism. It is used extensively by the scientific community as a name given to some stretches of deoxyribonucleic acids (DNA) and ribonucleic acids (RNA) that code for a polypeptide or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains. Genes hold the information to build and maintain an organism's cells and pass genetic traits to offspring. All organisms have genes corresponding to various biological traits, some of which are instantly visible, such as eye color or number of limbs, and some of which are not, such as blood type, increased risk for specific diseases, or the thousands of basic biochemical processes that comprise life. The word gene is derived from the Greek word genesis meaning "birth", or genos meaning "origin" (see pangenesis). A modern working definition of a gene is "a locatable region of genomic sequence, corresponding to a unit of inheritance, which is associated with regulatory regions, transcribed regions, and or other functional sequence regions ". [1][2] Colloquial usage of the term gene (e.g., "good genes", "hair color gene") may actually refer to an allele: a gene is the basic instruction— a sequence of nucleic acids (DNA or, in the case of certain viruses RNA), while an allele is one variant of that gene. Thus, when the mainstream press refers to "having" a "gene" for a specific trait, this is customarily inaccurate. In most cases, all people would have a gene for the trait in question, although certain people will have a specific allele of that gene, which results in the trait variant. Further, genes code for proteins, which might result in identifiable traits, but it is the gene (genotype), not the trait (phenotype), which is inherited. Big genes are a class of genes whose nuclear transcript spans 500 kb (1 kb = 1,000 base pairs) or more of chromosomal DNA. The largest of the big genes is the gene for dystrophin, which spans 2.3 Mb. Many big genes have modestly sized mRNAs; the exons encoding these RNAs typically encompass about 1% of the total chromosomal gene region in which they occur. Contents 1 History 2 Mendelian inheritance and classical genetics 3 Physical definitions
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Characterstics and Structure of Gene
Transcript of Characterstics and Structure of Gene
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1/15/2015 GeneWikipedia,thefreeencyclopedia
http://en.wikipedia.org/wiki/Gene 1/17
ThisstylisticdiagramshowsageneinrelationtothedoublehelixstructureofDNAandtoachromosome(right).ThechromosomeisXshapedbecauseitisdividing.Intronsareregionsoftenfoundineukaryotegenesthatareremovedinthesplicingprocess(aftertheDNAistranscribedintoRNA):Onlytheexonsencodetheprotein.Thediagramlabelsaregionofonly55orsobasesasagene.Inreality,mostgenesarehundredsoftimeslonger.
GeneFromWikipedia,thefreeencyclopedia
Ageneisthemolecularunitofheredityofalivingorganism.Itisusedextensivelybythescientificcommunityasanamegiventosomestretchesofdeoxyribonucleicacids(DNA)andribonucleicacids(RNA)thatcodeforapolypeptideorforanRNAchainthathasafunctionintheorganism.Livingbeingsdependongenes,astheyspecifyallproteinsandfunctionalRNAchains.Genesholdtheinformationtobuildandmaintainanorganism'scellsandpassgenetictraitstooffspring.Allorganismshavegenescorrespondingtovariousbiologicaltraits,someofwhichareinstantlyvisible,suchaseyecolorornumberoflimbs,andsomeofwhicharenot,suchasbloodtype,increasedriskforspecificdiseases,orthethousandsofbasicbiochemicalprocessesthatcompriselife.ThewordgeneisderivedfromtheGreekwordgenesismeaning"birth",orgenosmeaning"origin"(seepangenesis).
Amodernworkingdefinitionofageneis"alocatableregionofgenomicsequence,correspondingtoaunitofinheritance,whichisassociatedwithregulatoryregions,transcribedregions,andorotherfunctionalsequenceregions".[1][2]Colloquialusageofthetermgene(e.g.,"goodgenes","haircolorgene")mayactuallyrefertoanallele:ageneisthebasicinstructionasequenceofnucleicacids(DNAor,inthecaseofcertainvirusesRNA),whileanalleleisonevariantofthatgene.Thus,whenthemainstreampressrefersto"having"a"gene"foraspecifictrait,thisiscustomarilyinaccurate.Inmostcases,allpeoplewouldhaveageneforthetraitinquestion,althoughcertainpeoplewillhaveaspecificalleleofthatgene,whichresultsinthetraitvariant.Further,genescodeforproteins,whichmightresultinidentifiabletraits,butitisthegene(genotype),notthetrait(phenotype),whichisinherited.
Biggenesareaclassofgeneswhosenucleartranscriptspans500kb(1kb=1,000basepairs)ormoreofchromosomalDNA.Thelargestofthebiggenesisthegenefordystrophin,whichspans2.3Mb.ManybiggeneshavemodestlysizedmRNAstheexonsencodingtheseRNAstypicallyencompassabout1%ofthetotalchromosomalgeneregioninwhichtheyoccur.
Contents
1History2Mendelianinheritanceandclassicalgenetics3Physicaldefinitions
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1/15/2015 GeneWikipedia,thefreeencyclopedia
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ThechemicalstructureofafourbasefragmentofaDNAdoublehelix.
GregorMendel
3.1RNAgenesandgenomesintheworld3.2Functionalstructureofagene3.3Chromosomes
4Geneexpression4.1Geneticcode4.2Transcription4.3Translation
5DNAreplicationandinheritance5.1Molecularinheritance
6Mutation7Genome
7.1Chromosomalorganization7.2Numberofgenes7.3Geneticandgenomicnomenclature7.4Essentialgenes
8Evolutionaryconceptofagene9Genetargetingandimplications10Changingconcept11Seealso12Notesandreferences13Bibliography14Externallinks
History
TheexistenceofgeneswasfirstimpliedfromtheworkofGregorMendel(18221884),who,betweentheyearsof1857to1864planted8000commonediblepeaplantsandstudiedandtabulatedtheinheritancepatternsinpeaplants(Pisum)trackinginheritanceoftraitsfromparenttooffspringanddescribingthesemathematicallyas2ncombinationswherenisthenumberofdifferingcharacteristicsintheoriginalpeas.Althoughhedidnotusethetermgene,heexplainedhisresultsintermsofinheritedcharacteristics.Thenotionofagene[3]isevolvingwiththescienceofgenetics,butbeganwhenMendelnoticedthatbiologicalvariationsareinheritedfromparentorgrandparentorganismsasspecific,discretetraitsandaretransmittedthusunalteredfromtheoriginalsource.PriortoMendel'swork,thedominanttheoryofhereditywasoneofblendinginheritance,pangenesis,whichsuggestedthateachparentcontributedfluidstothefertilisationprocess
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andthatinmeiosisthetraitsoftheparentsblendedandmixedtoproducetheoffspring.AlthoughMendel'sworkwaslargelyunrecognizedafteritsfirstpublicationin1866,itwas'rediscovered'in1900bythreeEuropeanscientists,HugodeVries,CarlCorrens,andErichvonTschermak,whoclaimedtohavereachedsimilarconclusionsintheirownresearch.However,thesescientistswerenotyetawareoftheidentityofthe'discreteunits'onwhichgeneticmaterialresides.Thebiologicalentityresponsiblefordefiningtraitswaslatertermedagene,butthebiologicalbasisforinheritanceremainedunknownuntilDNAwasidentifiedasthegeneticmaterialinthe1940s.Mendelwasalsothefirsttoshowindependentassortment,thedistinctionbetweendominantandrecessivetraits,thedistinctionbetweenaheterozygoteandhomozygote,thephenomenonofdiscontinuinginheritanceandwhatwouldlaterbedescribedasgenotype(thegeneticmaterialofanorganism)andphenotype(thevisibletraitsofthatorganism)andtheconversionofoneformintoanotherwithinfewgenerations.
CharlesDarwinusedthetermgemmuletodescribeamicroscopicunitofinheritance,andwhatwouldlaterbecomeknownaschromosomeshadbeenobservedseparatingoutduringcelldivisionbyWilhelmHofmeisterasearlyas1848.Theideathatchromosomesarethecarriersofinheritancewasexpressedin1883byWilhelmRoux.Darwinalsocoinedthewordpangenesisby(1868).[4]ThewordpangenesisismadefromtheGreekwordspan(aprefixmeaning"whole","encompassing")andgenesis("birth")orgenos("origin").
Mendel'sconceptwasgivenanamebyHugodeVriesin1889,inhisbookIntracellularPangenesisalthoughprobablyunawareofMendel'sworkatthetime,hecoinedtheterm"pangen"for"thesmallestparticle[representing]onehereditarycharacteristic".[5]DanishbotanistWilhelmJohannsencoinedtheword"gene"("gen"inDanishandGerman)in1909todescribethefundamentalphysicalandfunctionalunitsofheredity,[6]whiletherelatedwordgeneticswasfirstusedbyWilliamBatesonin1905.[7]HederivedthewordfromdeVries'"pangen".Intheearly1900s,Mendel'sworkreceivedrenewedattentionfromscientists.In1910,ThomasHuntMorganshowedthatgenesresideonspecificchromosomes.Helatershowedthatgenesoccupyspecificlocationsonthechromosome.Withthisknowledge,MorganandhisstudentsbeganthefirstchromosomalmapofthefruitflyDrosophila.In1928,FrederickGriffithshowedthatgenescouldbetransferred.InwhatisnowknownasGriffith'sexperiment,injectionsintoamouseofadeadlystrainofbacteriathathadbeenheatkilledtransferredgeneticinformationtoasafestrainofthesamebacteria,killingthemouse.
Aseriesofsubsequentdiscoveriesledtotherealizationdecadeslaterthatchromosomeswithincellsarethecarriersofgeneticmaterial,andthattheyaremadeofDNA(deoxyribonucleicacid),apolymericmoleculefoundinallcellsonwhichthe'discreteunits'ofMendelianinheritanceareencoded.In1941,GeorgeWellsBeadleandEdwardLawrieTatumshowedthatmutationsingenescausederrorsinspecificstepsinmetabolicpathways.Thisshowedthatspecificgenescodeforspecificproteins,leadingtothe"onegene,oneenzyme"hypothesis.[7]OswaldAvery,ColinMunroMacLeod,andMaclynMcCartyshowedin1944thatDNAholdsthegene'sinformation.[8]In1952,RosalindFranklinandRaymondGoslingproducedastrikinglyclearxraydiffractionpatternindicatingahelicalform,andin1953,JamesD.WatsonandFrancisCrickdemonstratedthemolecularstructureofDNA.Together,thesediscoveriesestablishedthecentraldogmaofmolecularbiology,whichstatesthatproteinsaretranslatedfromRNAwhichistranscribedfromDNA.Thisdogmahassincebeenshowntohaveexceptions,suchasreversetranscriptioninretroviruses.
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Crossingbetweentwopeaplantsheterozygousforpurple(B,dominant)andwhite(b,recessive)blossoms
In1972,WalterFiersandhisteamattheLaboratoryofMolecularBiologyoftheUniversityofGhent(Ghent,Belgium)werethefirsttodeterminethesequenceofagene:thegeneforBacteriophageMS2coatprotein.[9]RichardJ.RobertsandPhillipSharpdiscoveredin1977thatgenescanbesplitintosegments.Thisledtotheideathatonegenecanmakeseveralproteins.Recently(asof20032006),biologicalresultsletthenotionofgeneappearmoreslippery.Inparticular,genesdonotseemtositsidebysideonDNAlikediscretebeads.Instead,regionsoftheDNAproducingdistinctproteinsmayoverlap,sothattheideaemergesthat"genesareonelongcontinuum".[1]Itwasfirsthypothesizedin1986byWalterGilbertthatneitherDNAnorproteinwouldberequiredinsuchaprimitivesystemasthatofaveryearlystageoftheearthifRNAcouldperformassimplyacatalystandgeneticinformationstorageprocessor.
ThemodernstudyofgeneticsatthelevelofDNAisknownasmoleculargeneticsandthesynthesisofmoleculargeneticswithtraditionalDarwinianevolutionisknownasthemodernevolutionarysynthesis.
Mendelianinheritanceandclassicalgenetics
AccordingtothetheoryofMendelianinheritance,variationsinphenotypetheobservablephysicalandbehavioralcharacteristicsofanorganismaredueinparttovariationsingenotype,ortheorganism'sparticularsetofgenes,eachofwhichspecifiesaparticulartrait.Differentformsofagene,whichmaygiverisetodifferentphenotypes,areknownasalleles.OrganismssuchasthepeaplantsMendelworkedon,alongwithmanyplantsandanimals,havetwoallelesforeachtrait,oneinheritedfromeachparent.Allelesmaybedominantorrecessivedominantallelesgiverisetotheircorrespondingphenotypeswhenpairedwithanyotheralleleforthesametrait,whereasrecessiveallelesgiverisetotheircorrespondingphenotypeonlywhenpairedwithanothercopyofthesameallele.Forexample,iftheallelespecifyingtallstemsinpeaplantsisdominantovertheallelespecifyingshortstems,thenpeaplantsthatinheritonetallallelefromoneparentandoneshortallelefromtheotherparentwillalsohavetallstems.Mendel'sworkdemonstratedthatallelesassortindependentlyintheproductionofgametes,orgermcells,ensuringvariationinthenextgeneration.
Physicaldefinitions
RNAgenesandgenomesintheworld
Whenproteinsaremanufactured,thegeneisfirstcopiedintoRNAasanintermediateproduct.Inothercases,theRNAmoleculesaretheactualfunctionalproducts.Forexample,RNAsknownasribozymesarecapableofenzymaticfunction,andmicroRNAhasaregulatoryrole.TheDNAsequencesfromwhichsuchRNAsaretranscribedareknownasRNAgenes.
SomevirusesstoretheirentiregenomesintheformofRNA,andcontainnoDNAatall.BecausetheyuseRNAtostoregenes,theircellularhostsmaysynthesizetheirproteinsassoonastheyareinfectedandwithoutthedelayinwaitingfortranscription.Ontheotherhand,RNAretroviruses,suchasHIV,require
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Diagramofthe"typical"eukaryoticproteincodinggene.PromotersandenhancersdeterminewhatportionsoftheDNAwillbetranscribedintotheprecursormRNA(premRNA).ThepremRNAisthensplicedintomessengerRNA(mRNA)whichislatertranslatedintoprotein.
thereversetranscriptionoftheirgenomefromRNAintoDNAbeforetheirproteinscanbesynthesized.In2006,FrenchresearcherscameacrossapuzzlingexampleofRNAmediatedinheritanceinmice.MicewithalossoffunctionmutationinthegeneKithavewhitetails.OffspringofthesemutantscanhavewhitetailsdespitehavingonlynormalKitgenes.TheresearchteamtracedthiseffectbacktomutatedKitRNA.[10]WhileRNAiscommonasgeneticstoragematerialinviruses,inmammalsinparticularRNAinheritancehasbeenobservedveryrarely.
Functionalstructureofagene
ThevastmajorityoflivingorganismsencodetheirgenesinlongstrandsofDNA(deoxyribonucleicacid).DNAconsistsofachainmadefromfourtypesofnucleotidesubunits,eachcomposedof:afivecarbonsugar(2'deoxyribose),aphosphategroup,andoneofthefourbasesadenine,cytosine,guanine,andthymine.ThemostcommonformofDNAinacellisinadoublehelixstructure,inwhichtwoindividualDNAstrandstwistaroundeachotherinarighthandedspiral.Inthisstructure,thebasepairingrulesspecifythatguaninepairswithcytosineandadeninepairswiththymine.Thebasepairingbetweenguanineandcytosineformsthreehydrogenbonds,whereasthebasepairingbetweenadenineandthymineformstwohydrogenbonds.Thetwostrandsinadoublehelixmustthereforebecomplementary,thatis,theirbasesmustalignsuchthattheadeninesofonestrandarepairedwiththethyminesoftheotherstrand,andsoon.
Duetothechemicalcompositionofthepentoseresiduesofthebases,DNAstrandshavedirectionality.OneendofaDNApolymercontainsanexposedhydroxylgrouponthedeoxyribosethisisknownasthe3'endofthemolecule.Theotherendcontainsanexposedphosphategroupthisisthe5'end.ThedirectionalityofDNAisvitallyimportanttomanycellularprocesses,sincedoublehelicesarenecessarilydirectional(astrandrunning5'3'pairswithacomplementarystrandrunning3'5'),andprocessessuchasDNAreplicationoccurinonlyonedirection.Allnucleicacidsynthesisinacelloccursinthe5'3'direction,becausenewmonomersareaddedviaadehydrationreactionthatusestheexposed3'hydroxylasanucleophile.
TheexpressionofgenesencodedinDNAbeginsbytranscribingthegeneintoRNA,asecondtypeofnucleicacidthatisverysimilartoDNA,butwhosemonomerscontainthesugarriboseratherthandeoxyribose.RNAalsocontainsthebaseuracilinplaceofthymine.RNAmoleculesarelessstablethanDNAandaretypicallysinglestranded.Genesthatencodeproteinsarecomposedofaseriesofthree
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nucleotidesequencescalledcodons,whichserveasthewordsinthegeneticlanguage.Thegeneticcodespecifiesthecorrespondenceduringproteintranslationbetweencodonsandaminoacids.Thegeneticcodeisnearlythesameforallknownorganisms.
AllgeneshaveregulatoryregionsinadditiontoregionsthatexplicitlycodeforaproteinorRNAproduct.Aregulatoryregionsharedbyalmostallgenesisknownasthepromoter,whichprovidesapositionthatisrecognizedbythetranscriptionmachinerywhenageneisabouttobetranscribedandexpressed.Agenecanhavemorethanonepromoter,resultinginRNAsthatdifferinhowfartheyextendinthe5'end.[11]Althoughpromoterregionshaveaconsensussequencethatisthemostcommonsequenceatthisposition,somegeneshave"strong"promotersthatbindthetranscriptionmachinerywell,andothershave"weak"promotersthatbindpoorly.Theseweakpromotersusuallypermitalowerrateoftranscriptionthanthestrongpromoters,becausethetranscriptionmachinerybindstothemandinitiatestranscriptionlessfrequently.Otherpossibleregulatoryregionsincludeenhancers,whichcancompensateforaweakpromoter.Mostregulatoryregionsare"upstream"thatis,beforeortowardthe5'endofthetranscriptioninitiationsite.Eukaryoticpromoterregionsaremuchmorecomplexanddifficulttoidentifythanprokaryoticpromoters.
Manyprokaryoticgenesareorganizedintooperons,orgroupsofgeneswhoseproductshaverelatedfunctionsandwhicharetranscribedasaunit.Bycontrast,eukaryoticgenesaretranscribedonlyoneatatime,butmayincludelongstretchesofDNAcalledintronswhicharetranscribedbutnevertranslatedintoprotein(theyaresplicedoutbeforetranslation).Splicingcanalsooccurinprokaryoticgenes,butislesscommonthanineukaryotes.[12]
Chromosomes
Thetotalcomplementofgenesinanorganismorcellisknownasitsgenome,whichmaybestoredononeormorechromosomestheregionofthechromosomeatwhichaparticulargeneislocatediscalleditslocus.Achromosomeconsistsofasingle,verylongDNAhelixonwhichthousandsofgenesareencoded.Prokaryotesbacteriaandarchaeatypicallystoretheirgenomesonasinglelarge,circularchromosome,sometimessupplementedbyadditionalsmallcirclesofDNAcalledplasmids,whichusuallyencodeonlyafewgenesandareeasilytransferablebetweenindividuals.Forexample,thegenesforantibioticresistanceareusuallyencodedonbacterialplasmidsandcanbepassedbetweenindividualcells,eventhoseofdifferentspecies,viahorizontalgenetransfer.Althoughsomesimpleeukaryotesalsopossessplasmidswithsmallnumbersofgenes,themajorityofeukaryoticgenesarestoredonmultiplelinearchromosomes,whicharepackedwithinthenucleusincomplexwithstorageproteinscalledhistones.ThemannerinwhichDNAisstoredonthehistone,aswellaschemicalmodificationsofthehistoneitself,areregulatorymechanismsgoverningwhetheraparticularregionofDNAisaccessibleforgeneexpression.Theendsofeukaryoticchromosomesarecappedbylongstretchesofrepetitivesequencescalledtelomeres,whichdonotcodeforanygeneproductbutarepresenttopreventdegradationofcodingandregulatoryregionsduringDNAreplication.Thelengthofthetelomerestendstodecreaseeachtimethegenomeisreplicatedinpreparationforcelldivisionthelossoftelomereshasbeenproposedasanexplanationforcellularsenescence,orthelossoftheabilitytodivide,andbyextensionfortheagingprocessinorganisms.[13]
Whereasthechromosomesofprokaryotesarerelativelygenedense,thoseofeukaryotesoftencontainsocalled"junkDNA",orregionsofDNAthatservenoobviousfunction.SimplesinglecelledeukaryoteshaverelativelysmallamountsofsuchDNA,whereasthegenomesofcomplexmulticellularorganisms,
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SchematicdiagramofasinglestrandedRNAmoleculeillustratingthepositionofthreebasecodons.
includinghumans,containanabsolutemajorityofDNAwithoutanidentifiedfunction.[14]Howeveritnowappearsthat,althoughproteincodingDNAmakesupbarely2%ofthehumangenome,about80%ofthebasesinthegenomemaybeexpressed,sotheterm"junkDNA"maybeamisnomer.[2]
Geneexpression
Inallorganisms,therearetwomajorstepsseparatingaproteincodinggenefromitsprotein:First,theDNAonwhichthegeneresidesmustbetranscribedfromDNAtomessengerRNA(mRNA)and,second,itmustbetranslatedfrommRNAtoprotein.RNAcodinggenesmuststillgothroughthefirststep,butarenottranslatedintoprotein.TheprocessofproducingabiologicallyfunctionalmoleculeofeitherRNAorproteiniscalledgeneexpression,andtheresultingmoleculeitselfiscalledageneproduct.
Geneticcode
Thegeneticcodeisthesetofrulesbywhichinformationencodedwithinageneistranslatedintoafunctionalprotein.EachgeneconsistsofaspecificsequenceofnucleotidesencodedinDNAorRNA.Thenucleotidebeingmadeupofasugar,aphosphatemoleculeandaspecificbase(adenine,thymine,cytosine,guanineorsometimesuracil[thymineisreplacedwithuracilinsomeviruses[15]])acorrespondencebetweennucleotides,thebasicbuildingblocksofgeneticmaterial,andaminoacids,thebasicbuildingblocksofproteins,mustbeestablishedforgenestobesuccessfullytranslatedintofunctionalproteins.Setsofthreenucleotides,knownascodons,eachcorrespondtoaspecificaminoacidortoasignalthreecodonsareknownas"stopcodons"and,insteadofspecifyinganewaminoacid,alertthetranslationmachinerythattheendofthegenehasbeenreached,justasaspecificsetof3bases,"AUG",knownasthe"startcodon",signifiesthegenetostarttranscribing.Thereare64possiblecodons(fourpossiblenucleotidesateachofthreepositions,hence43possiblecodons)andonly20standardaminoacidshencethecodeisredundantandmultiplecodonscanspecifythesameaminoacid.Thecorrespondencebetweencodonsandaminoacidsisnearlyuniversalamongallknownlivingorganisms.
Transcription
TheprocessofgenetictranscriptionproducesasinglestrandedRNAmoleculeknownasmessengerRNA,whosenucleotidesequenceiscomplementarytotheDNAfromwhichitwastranscribed.TheDNAstrandwhosesequencematchesthatoftheRNAisknownasthecodingstrandandthestrandfromwhichtheRNAwassynthesizedisthetemplatestrand.TranscriptionisperformedbyanenzymecalledanRNApolymerase,whichreadsthetemplatestrandinthe3'to5'directionandsynthesizestheRNAfrom5'to3'.Toinitiatetranscription,thepolymerasefirstrecognizesandbindsapromoterregionofthegene.Thusamajormechanismofgeneregulationistheblockingorsequesteringofthepromoterregion,eitherbytightbindingbyrepressormoleculesthatphysicallyblockthepolymerase,orbyorganizingtheDNAsothatthepromoterregionisnotaccessible.
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Inprokaryotes,transcriptionoccursinthecytoplasmforverylongtranscripts,translationmaybeginatthe5'endoftheRNAwhilethe3'endisstillbeingtranscribed.Ineukaryotes,transcriptionnecessarilyoccursinthenucleus,wherethecell'sDNAissequesteredtheRNAmoleculeproducedbythepolymeraseisknownastheprimarytranscriptandmustundergoposttranscriptionalmodificationsbeforebeingexportedtothecytoplasmfortranslation.Thesplicingofintronspresentwithinthetranscribedregionisamodificationuniquetoeukaryotesalternativesplicingmechanismscanresultinmaturetranscriptsfromthesamegenehavingdifferentsequencesandthuscodingfordifferentproteins.Thisisamajorformofregulationineukaryoticcells.
Translation
TranslationistheprocessbywhichamaturemRNAmoleculeisusedasatemplateforsynthesizinganewprotein.Translationiscarriedoutbyribosomes,largecomplexesofRNAandproteinresponsibleforcarryingoutthechemicalreactionstoaddnewaminoacidstoagrowingpolypeptidechainbytheformationofpeptidebonds.Thegeneticcodeisreadthreenucleotidesatatime,inunitscalledcodons,viainteractionswithspecializedRNAmoleculescalledtransferRNA(tRNA).EachtRNAhasthreeunpairedbasesknownastheanticodonthatarecomplementarytothecodonitreadsthetRNAisalsocovalentlyattachedtotheaminoacidspecifiedbythecomplementarycodon.WhenthetRNAbindstoitscomplementarycodoninanmRNAstrand,theribosomeligatesitsaminoacidcargotothenewpolypeptidechain,whichissynthesizedfromaminoterminustocarboxylterminus.Duringandafteritssynthesis,thenewproteinmustfoldtoitsactivethreedimensionalstructurebeforeitcancarryoutitscellularfunction.
DNAreplicationandinheritance
Thegrowth,development,andreproductionoforganismsreliesoncelldivision,ortheprocessbywhichasinglecelldividesintotwousuallyidenticaldaughtercells.ThisrequiresfirstmakingaduplicatecopyofeverygeneinthegenomeinaprocesscalledDNAreplication.ThecopiesaremadebyspecializedenzymesknownasDNApolymerases,which"read"onestrandofthedoublehelicalDNA,knownasthetemplatestrand,andsynthesizeanewcomplementarystrand.BecausetheDNAdoublehelixisheldtogetherbybasepairing,thesequenceofonestrandcompletelyspecifiesthesequenceofitscomplementhenceonlyonestrandneedstobereadbytheenzymetoproduceafaithfulcopy.TheprocessofDNAreplicationissemiconservativethatis,thecopyofthegenomeinheritedbyeachdaughtercellcontainsoneoriginalandonenewlysynthesizedstrandofDNA.[16]
AfterDNAreplicationiscomplete,thecellmustphysicallyseparatethetwocopiesofthegenomeanddivideintotwodistinctmembraneboundcells.Inprokaryotesbacteriaandarchaeathisusuallyoccursviaarelativelysimpleprocesscalledbinaryfission,inwhicheachcirculargenomeattachestothecellmembraneandisseparatedintothedaughtercellsasthemembraneinvaginatestosplitthecytoplasmintotwomembraneboundportions.Binaryfissionisextremelyfastcomparedtotheratesofcelldivisionineukaryotes.EukaryoticcelldivisionisamorecomplexprocessknownasthecellcycleDNAreplicationoccursduringaphaseofthiscycleknownasSphase,whereastheprocessofsegregatingchromosomesandsplittingthecytoplasmoccursduringMphase.Inmanysinglecelledeukaryotessuchasyeast,reproductionbybuddingiscommon,whichresultsinasymmetricalportionsofcytoplasminthetwodaughtercells.
Molecularinheritance
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Theduplicationandtransmissionofgeneticmaterialfromonegenerationofcellstothenextisthebasisformolecularinheritance,andthelinkbetweentheclassicalandmolecularpicturesofgenes.Organismsinheritthecharacteristicsoftheirparentsbecausethecellsoftheoffspringcontaincopiesofthegenesintheirparents'cells.Inasexuallyreproducingorganisms,theoffspringwillbeageneticcopyorcloneoftheparentorganism.Insexuallyreproducingorganisms,aspecializedformofcelldivisioncalledmeiosisproducescellscalledgametesorgermcellsthatarehaploid,orcontainonlyonecopyofeachgene.Thegametesproducedbyfemalesarecalledeggsorova,andthoseproducedbymalesarecalledsperm.Twogametesfusetoformafertilizedegg,asinglecellthatonceagainhasadiploidnumberofgeneseachwithonecopyfromthemotherandonecopyfromthefather.
Duringtheprocessofmeioticcelldivision,aneventcalledgeneticrecombinationorcrossingovercansometimesoccur,inwhichalengthofDNAononechromatidisswappedwithalengthofDNAonthecorrespondingsisterchromatid.Thishasnoeffectiftheallelesonthechromatidsarethesame,butresultsinreassortmentofotherwiselinkedallelesiftheyaredifferent.TheMendelianprincipleofindependentassortmentassertsthateachofaparent'stwogenesforeachtraitwillsortindependentlyintogameteswhichalleleanorganisminheritsforonetraitisunrelatedtowhichalleleitinheritsforanothertrait.Thisisinfactonlytrueforgenesthatdonotresideonthesamechromosome,orarelocatedveryfarfromoneanotheronthesamechromosome.Theclosertwogeneslieonthesamechromosome,themorecloselytheywillbeassociatedingametesandthemoreoftentheywillappeartogethergenesthatareverycloseareessentiallyneverseparatedbecauseitisextremelyunlikelythatacrossoverpointwilloccurbetweenthem.Thisisknownasgeneticlinkage.
Mutation
DNAreplicationisforthemostpartextremelyaccurate,withanerrorratepersiteofaround106to1010
ineukaryotes.[16](Althoughinprokaryotesandviruses,therateismuchhigher.)Rare,spontaneousalterationsinthebasesequenceofaparticulargenearisefromanumberofsources,suchaserrorsinDNAreplicationandtheaftermathofDNAdamage.Theseerrorsarecalledmutations.ThecellcontainsmanyDNArepairmechanismsforpreventingmutationsandmaintainingtheintegrityofthegenomehowever,insomecasessuchasbreaksinbothDNAstrandsofachromosomerepairingthephysicaldamagetothemoleculeisahigherprioritythanproducinganexactcopy.Duetothedegeneracyofthegeneticcode,somemutationsinproteincodinggenesaresilent,orproducenochangeintheaminoacidsequenceoftheproteinforwhichtheycodeforexample,thecodonsUCUandUCCbothcodeforserine,sotheUCmutationhasnoeffectontheprotein.Mutationsthatdohavephenotypiceffectsaremostoftenneutralordeleterioustotheorganism.Variantsmayconferbenefitstotheorganism'sfitnessitiscommonlythoughtthatmutationsmayproducebeneficialvariants.Themostcommonmutationsincludepointmutationsinwhichasinglecodonisreplaced,frameshiftmutationwhereasinglenucleotidebaseisinsertedordeletedfromtheDNAstrandsothatallbasesareshiftedover,silentmutationswhereasinglenucleotidebaseisreplacedbutwithoutcausingachangefortheaminoacidbeingcodedfor,andnonsensemutations,whereachangeinasinglenucleotidebasecausesacodontobeturnedintoastopcodonhenceterminatingtranscriptionatthispoint.
Mutationspropagatedtothenextgenerationleadtovariationswithinaspecies'population.Variantsofasinglegeneareknownasalleles,anddifferencesinallelesmaygiverisetodifferencesintraits.Althoughitisrareforthevariantsinasinglegenetohaveclearlydistinguishablephenotypiceffects,certainwelldefinedtraitsareinfactcontrolledbysinglegeneticloci.Agene'smostcommonalleleiscalledthewildtypeallele,andrareallelesarecalledmutants.However,thisdoesnotimplythatthewildtypealleleisthe
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Theproteinencodingcomponentofthehumangenome,categorizedbyfunctionofeachgeneproduct,givenbothasnumberofgenesandaspercentageofallgenes.[17]
ancestorfromwhichthemutantsaredescended.Forthemostpart,thesemutationsarerecessiveandarephasedoutquickly.However,onoccasionthesemutationsappearasdominanttootheralleles,becomingpredominantandincreasingintheratetheyareseeninapopulation.
Genome
Chromosomalorganization
Thetotalcomplementofgenesinanorganismorcellisknownasitsgenome.Inprokaryotes,thevastmajorityofgenesarelocatedonasinglechromosomeofcircularDNA,whileeukaryotesusuallypossessmultipleindividuallinearDNAhelicespackedintodenseDNAproteincomplexescalledchromosomes.Genesthatappeartogetherononechromosomeofonespeciesmayappearonseparatechromosomesinanotherspecies.Manyspeciescarrymorethanonecopyoftheirgenomewithineachoftheirsomaticcells.Cellsororganismswithonlyonecopyofeachchromosomearecalledhaploidthosewithtwocopiesarecalleddiploidandthosewithmorethantwocopiesarecalledpolyploid.Thecopiesofgenesonthechromosomesarenotnecessarilyidentical.Insexuallyreproducingorganisms,onecopyisnormallyinheritedfromeachparent.
Numberofgenes
Earlyestimatesofthenumberofhumangenesthatusedexpressedsequencetagdataputitat50000100000.[18]Followingthesequencingofthehumangenomeandothergenomes,ithasbeenfoundthatratherfewgenes(~20000inhuman,mouseandfly,~13000inroundworm,>46,000inrice[19])encodealltheproteinsinanorganism.[20]Theseproteincodingsequencesmakeup12%ofthehumangenome.[21]Alargepartofthegenomeistranscribedhowever,tointrons,retrotransposonsandseeminglyalargearrayofnoncodingRNAs.[20][21]Totalnumberofproteins(theEarth'sproteome)isestimatedtobe5millionsequences.[22]
Geneticandgenomicnomenclature
GenenomenclaturehasbeenestablishedbytheHUGOGeneNomenclatureCommittee(HGNC)foreachknownhumangeneintheformofanapprovedgenenameandsymbol(shortformabbreviation).AllapprovedsymbolsarestoredintheHGNCDatabase(http://www.genenames.org/cgibin/hgnc_search.pl).
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Eachsymbolisuniqueandeachgeneisonlygivenoneapprovedgenesymbol.Thisalsofacilitateselectronicdataretrievalfrompublications.Inpreferenceeachsymbolmaintainsparallelconstructionindifferentmembersofagenefamilyandcanbeusedinotherspecies,especiallythemouse.
Essentialgenes
Essentialgenesarethosegenesofanorganismthatarethoughttobecriticalforitssurvival.Surprisinglyfewgeneshavebeenshowntobeabsolutelyessentialforthesurvivalofbacteria,e.g.onlyabout10%ofthe~4,200genesofEscherichiacoli.
Evolutionaryconceptofagene
GeorgeC.Williamsfirstexplicitlyadvocatedthegenecentricviewofevolutioninhis1966bookAdaptationandNaturalSelection.Heproposedanevolutionaryconceptofgenetobeusedwhenwearetalkingaboutnaturalselectionfavoringsomegenes.Thedefinitionis:"thatwhichsegregatesandrecombineswithappreciablefrequency."Accordingtothisdefinition,evenanasexualgenomecouldbeconsideredagene,insofarthatithaveanappreciablepermanencythroughmanygenerations.
Thedifferenceis:themoleculargenetranscribesasaunit,andtheevolutionarygeneinheritsasaunit.
RichardDawkins'booksTheSelfishGene(1976)andTheExtendedPhenotype(1982)defendedtheideathatthegeneistheonlyreplicatorinlivingsystems.Thismeansthatonlygenestransmittheirstructurelargelyintactandarepotentiallyimmortalintheformofcopies.So,genesshouldbetheunitofselection.InRiverOutofEden,Dawkinsfurtherrefinedtheideaofgenecentricselectionbydescribinglifeasariverofcompatiblegenesflowingthroughgeologicaltime.Scoopupabucketofgenesfromtheriverofgenes,andwehaveanorganismservingastemporarybodiesorsurvivalmachines.Ariverofgenesmayforkintotwobranchesrepresentingtwononinterbreedingspeciesasaresultofgeographicalseparation.
Genetargetingandimplications
Genetargetingiscommonlyreferredtotechniquesforalteringordisruptingmousegenesandprovidesthemousemodelsforstudyingtherolesofindividualgenesinembryonicdevelopment,humandisorders,aginganddiseases.Themousemodels,whereoneormoreofitsgenesaredeactivatedormadeinoperable,arecalledknockoutmice.Sincethefirstreportsinwhichhomologousrecombinationamonghomologouschromosomesinembryonicstemcellswasusedtogenerategenetargetedmice,[23]genetargetinghasproventobeapowerfulmeansofpreciselymanipulatingthemammaliangenome,producingatleasttenthousandmutantmousestrainsanditisnowpossibletointroducemutationsthatcanbeactivatedatspecifictimepoints,orinspecificcellsororgans,bothduringdevelopmentandintheadultanimal.[24][25]
Genetargetingstrategieshavebeenexpandedtoallkindsofmodifications,includingpointmutations,isoformdeletions,mutantallelecorrection,largepiecesofchromosomalDNAinsertionanddeletion,tissuespecificdisruptioncombinedwithspatialandtemporalregulationandsoon.Itispredictedthattheabilitytogeneratemousemodelswithpredictablephenotypeswillhaveamajorimpactonstudiesofallphasesofdevelopment,immunology,neurobiology,oncology,physiology,metabolism,andhumandiseases.Genetargetingisalsointheoryapplicabletospeciesfromwhichtotipotentembryonicstemcellscanbeestablished,andthereforemayofferapotentialtotheimprovementofdomesticanimalsandplants.[25][26]
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Changingconcept
Theconceptofthegenehaschangedconsiderably(seehistorysection).Fromtheoriginaldefinitionofa"unitofinheritance",thetermevolvedtomeanaDNAbasedunitthatcanexertitseffectsontheorganismthroughRNAorproteinproducts.Itwasalsopreviouslybelievedthatonegenemakesoneproteinthisconceptwasoverthrownbythediscoveryofalternativesplicingandtranssplicing.[7]
Thedefinitionofageneisstillchanging.ThefirstcasesofRNAbasedinheritancehavebeendiscoveredinmammals.[27]Evidenceisalsoaccumulatingthatthecontrolregionsofagenedonotnecessarilyhavetobeclosetothecodingsequenceonthelinearmoleculeorevenonthesamechromosome.Spilianakisandcolleaguesdiscoveredthatthepromoterregionoftheinterferongammageneonchromosome10andtheregulatoryregionsoftheT(H)2cytokinelocusonchromosome11comeintocloseproximityinthenucleuspossiblytobejointlyregulated.[28]Eventhecodingsequenceofageneitselfdoesn'thavetobeallonthesamechromosome:MarandeandBurgershowedthat,inthemitochondriaoftheprotistDiplonemapapillatum,"genesaresystematicallyfragmentedintosmallpiecesthatareencodedonseparatechromosomes,transcribedindividually,andthenconcatenatedintocontiguousmessengerRNAmolecules".[29]
Theconceptthatgenesareclearlydelimitedisalsobeingeroded.Thereisevidenceforfusedproteinsstemmingfromtwoadjacentgenesthatcanproducetwoseparateproteinproducts.Whileitisnotclearwhetherthesefusionproteinsarefunctional,thephenomenonismorefrequentthanpreviouslythought.[30]Evenmoregroundbreakingthanthediscoveryoffusedgenesistheobservationthatsomeproteinscanbecomposedofexonsfromfarawayregionsandevendifferentchromosomes.[2][31]Thisnewdatahasledtoanupdated,andprobablytentative,definitionofageneas"aunionofgenomicsequencesencodingacoherentsetofpotentiallyoverlappingfunctionalproducts".[7]Thisnewdefinitioncategorizesgenesbyfunctionalproducts,whethertheybeproteinsorRNA,ratherthanspecificDNAlociallregulatoryelementsofDNAarethereforeclassifiedasgeneassociatedregions.[7]
Seealso
CopynumbervariationDNAEpigeneticsFullgenomesequencingGenecentricviewofevolutionGenedosageGeneexpressionGenefamilyGenepatentGenepoolGeneredundancyGenetherapy
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Notesandreferences
GeneticalgorithmGeneticengineeringGeneticsGenomicsListofgenepredictionsoftwareListofnotablegenesPopulationgeneticsPredictivemedicinePseudogene
1. ^abPearsonH(2006)."Genetics:whatisagene?".Nature441(7092):398401.Bibcode:2006Natur.441..398P(http://adsabs.harvard.edu/abs/2006Natur.441..398P).doi:10.1038/441398a(http://dx.doi.org/10.1038%2F441398a).PMID16724031(https://www.ncbi.nlm.nih.gov/pubmed/16724031).
2. ^abcElizabethPennisi(2007)."DNAStudyForcesRethinkofWhatItMeanstoBeaGene".Science316(5831):15561557.doi:10.1126/science.316.5831.1556(http://dx.doi.org/10.1126%2Fscience.316.5831.1556).PMID17569836(https://www.ncbi.nlm.nih.gov/pubmed/17569836).
3. ^Noble,D.(Sep2008)."Genesandcausation"(http://rsta.royalsocietypublishing.org/cgi/pmidlookup?view=long&pmid=18559318)(Freefulltext).Philosophicaltransactions.SeriesA,Mathematical,physical,andengineeringsciences366(1878):30013015.Bibcode:2008RSPTA.366.3001N(http://adsabs.harvard.edu/abs/2008RSPTA.366.3001N).doi:10.1098/rsta.2008.0086(http://dx.doi.org/10.1098%2Frsta.2008.0086).ISSN1364503X(https://www.worldcat.org/issn/1364503X).PMID18559318(https://www.ncbi.nlm.nih.gov/pubmed/18559318).
4. ^DarwinC.(1868).AnimalsandPlantsunderDomestication(1868).5. ^Vries,H.de(1889)IntracellularPangenesis[1](http://www.esp.org/books/devries/pangenesis/facsimile/)
("pangen"definitiononpage7and40ofthis1910translationinEnglish)6. ^"TheHumanGenomeProjectTimeline"(http://www.genome.gov/25019879).Retrieved20060913.
7. ^abcdeGersteinMarkB.etal.Bruce,C.Rozowsky,J.S.Zheng,D.Du,J.Korbel,J.O.Emanuelsson,O.Zhang,Z.D.etal.(2007)."Whatisagene,postENCODE?Historyandupdateddefinition".GenomeResearch17(6):669681.doi:10.1101/gr.6339607(http://dx.doi.org/10.1101%2Fgr.6339607).PMID17567988(https://www.ncbi.nlm.nih.gov/pubmed/17567988).
8. ^SteinmanRM,MobergCL(February1994)."Atripletributetotheexperimentthattransformedbiology"(https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2191359).J.Exp.Med.179(2):37984.doi:10.1084/jem.179.2.379(http://dx.doi.org/10.1084%2Fjem.179.2.379).PMC2191359(https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2191359).PMID8294854(https://www.ncbi.nlm.nih.gov/pubmed/8294854).
-
1/15/2015 GeneWikipedia,thefreeencyclopedia
http://en.wikipedia.org/wiki/Gene 14/17
9. ^MinJouW,HaegemanG,YsebaertM,FiersW(1972)."NucleotidesequenceofthegenecodingforthebacteriophageMS2coatprotein".Nature237(5350):828.Bibcode:1972Natur.237...82J(http://adsabs.harvard.edu/abs/1972Natur.237...82J).doi:10.1038/237082a0(http://dx.doi.org/10.1038%2F237082a0).PMID4555447(https://www.ncbi.nlm.nih.gov/pubmed/4555447).
10. ^RassoulzadeganM,GrandjeanV,GounonP,VincentS,GillotI,CuzinFGrandjeanGounonVincentGillotCuzin(2006)."RNAmediatednonmendelianinheritanceofanepigeneticchangeinthemouse".Nature441(7092):46974.Bibcode:2006Natur.441..469R(http://adsabs.harvard.edu/abs/2006Natur.441..469R).doi:10.1038/nature04674(http://dx.doi.org/10.1038%2Fnature04674).PMID16724059(https://www.ncbi.nlm.nih.gov/pubmed/16724059).
11. ^MortazaviA,WilliamsBA,McCueK,SchaefferL,WoldB(May2008)."MappingandquantifyingmammaliantranscriptomesbyRNASeq".Nat.Methods5(7):6218.doi:10.1038/nmeth.1226(http://dx.doi.org/10.1038%2Fnmeth.1226).PMID18516045(https://www.ncbi.nlm.nih.gov/pubmed/18516045).
12. ^WoodsonSA(1998)."Ironingoutthekinks:splicingandtranslationinbacteria"(http://genesdev.cshlp.org/content/12/9/1243.full).GenesDev.12(9):12437.doi:10.1101/gad.12.9.1243(http://dx.doi.org/10.1101%2Fgad.12.9.1243).PMID9573040(https://www.ncbi.nlm.nih.gov/pubmed/9573040).Retrieved20090807.
13. ^BraigM,SchmittC(2006)."Oncogeneinducedsenescence:puttingthebrakesontumordevelopment".CancerRes66(6):28814.doi:10.1158/00085472.CAN054006(http://dx.doi.org/10.1158%2F00085472.CAN054006).PMID16540631(https://www.ncbi.nlm.nih.gov/pubmed/16540631).
14. ^InternationalHumanGenomeSequencingConsortium(2004)."Finishingtheeuchromaticsequenceofthehumangenome"(http://www.nature.com/nature/journal/v431/n7011/full/nature03001.html).Nature431(7011):93145.Bibcode:2004Natur.431..931H(http://adsabs.harvard.edu/abs/2004Natur.431..931H).doi:10.1038/nature03001(http://dx.doi.org/10.1038%2Fnature03001).PMID15496913(https://www.ncbi.nlm.nih.gov/pubmed/15496913).Retrieved20090807.
15. ^MeSH(2008)NationalLibraryofMedicineMedicalSubjectHeadings.Nationallibraryofmedicinehttp://www.nlm.nih.gov/cgi/mesh/2008/MB_cgi?mode=&term=RNA+Viruses&field=entry(accessed27September2011)B04.820.19990101.
16. ^abWatsonJD,BakerTA,BellSP,GannA,LevineM,LosickR(2004).MolecularBiologyoftheGene(5thed.).PeasonBenjaminCummings(ColdSpringHarborLaboratoryPress).ISBN080534635X.
17. ^PANTHERPieChart(http://www.pantherdb.org/chart/summary/pantherChart.jsp?filterLevel=1&chartType=1&listType=1&type=5&species=Homo%20sapiens)atthePANTHERClassificationSystemhomepage.RetrievedMay25,2011
18. ^SchulerGD,BoguskiMS,StewartEA,etal(October1996)."Agenemapofthehumangenome"(http://www.sciencemag.org/cgi/content/full/274/5287/540).Science274(5287):5406.Bibcode:1996Sci...274..540S(http://adsabs.harvard.edu/abs/1996Sci...274..540S).doi:10.1126/science.274.5287.540(http://dx.doi.org/10.1126%2Fscience.274.5287.540).PMID8849440(https://www.ncbi.nlm.nih.gov/pubmed/8849440).
19. ^YuJ,HuS,WangJ,etal.(April2002)."Adraftsequenceofthericegenome(OryzasativaL.ssp.indica)".Science296(5565):7992.Bibcode:2002Sci...296...79Y(http://adsabs.harvard.edu/abs/2002Sci...296...79Y).doi:10.1126/science.1068037(http://dx.doi.org/10.1126%2Fscience.1068037).PMID11935017(https://www.ncbi.nlm.nih.gov/pubmed/11935017).
-
1/15/2015 GeneWikipedia,thefreeencyclopedia
http://en.wikipedia.org/wiki/Gene 15/17
20. ^abCarninciP,HayashizakiY(April2007)."NoncodingRNAtranscriptionbeyondannotatedgenes".Curr.Opin.Genet.Dev.17(2):13944.doi:10.1016/j.gde.2007.02.008(http://dx.doi.org/10.1016%2Fj.gde.2007.02.008).PMID17317145(https://www.ncbi.nlm.nih.gov/pubmed/17317145).
21. ^abClaverieJM(September2005)."Fewergenes,morenoncodingRNA".Science309(5740):152930.Bibcode:2005Sci...309.1529C(http://adsabs.harvard.edu/abs/2005Sci...309.1529C).doi:10.1126/science.1116800(http://dx.doi.org/10.1126%2Fscience.1116800).PMID16141064(https://www.ncbi.nlm.nih.gov/pubmed/16141064).
22. ^CarolinaPerezIratxeta,etalPalidwor,GarethAndradeNavarro,MiguelA(2007)."TowardscompletionoftheEarth'sproteome"(http://www.nature.com/embor/journal/v8/n12/full/7401117.html).NatureEMBOreports8(12):11351141.doi:10.1038/sj.embor.7401117(http://dx.doi.org/10.1038%2Fsj.embor.7401117).PMC2267224(https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2267224).PMID18059312(https://www.ncbi.nlm.nih.gov/pubmed/18059312).
23. ^Thomas,KRCapecchi,MR.(1987)."Sitedirectedmutagenesisbygenetargetinginmouseembryoderivedstemcells".Cell51(3):50312.doi:10.1016/00928674(87)906465(http://dx.doi.org/10.1016%2F00928674%2887%29906465).PMID2822260(https://www.ncbi.nlm.nih.gov/pubmed/2822260).
24. ^The2007NobelPrizeinPhysiologyorMedicinePressRelease(http://nobelprize.org/nobel_prizes/medicine/laureates/2007/press.html)
25. ^abDeng,C.(2007)."InCelebrationofDr.MarioR.Capecchi'sNobelPrize"(http://www.biolsci.org/v03p0417.htm).IntJBiolSci3:417419.doi:10.7150/ijbs.3.417(http://dx.doi.org/10.7150%2Fijbs.3.417).
26. ^MarioR.Capecchi(http://www.hhmi.org/research/investigators/capecchi.html)27. ^RassoulzadeganM,GrandjeanV,GounonP,VincentS,GillotI,CuzinFGrandjeanGounonVincentGillot
Cuzin(May2006)."RNAmediatednonmendelianinheritanceofanepigeneticchangeinthemouse".Nature441(7092):46974.Bibcode:2006Natur.441..469R(http://adsabs.harvard.edu/abs/2006Natur.441..469R).doi:10.1038/nature04674(http://dx.doi.org/10.1038%2Fnature04674).PMID16724059(https://www.ncbi.nlm.nih.gov/pubmed/16724059).
28. ^SpilianakisCG,LaliotiMD,TownT,LeeGR,FlavellRALaliotiTownLeeFlavell(June2005)."Interchromosomalassociationsbetweenalternativelyexpressedloci".Nature435(7042):63745.Bibcode:2005Natur.435..637S(http://adsabs.harvard.edu/abs/2005Natur.435..637S).doi:10.1038/nature03574(http://dx.doi.org/10.1038%2Fnature03574).PMID15880101(https://www.ncbi.nlm.nih.gov/pubmed/15880101).
29. ^Marande,WilliamBurger,Gertraud(19October2007)."MitochondrialDNAasagenomicjigsawpuzzle".Science(AAAS)318(5849):415.Bibcode:2007Sci...318..415M(http://adsabs.harvard.edu/abs/2007Sci...318..415M).doi:10.1126/science.1148033(http://dx.doi.org/10.1126%2Fscience.1148033).PMID17947575(https://www.ncbi.nlm.nih.gov/pubmed/17947575).
30. ^ParraG,ReymondA,DabbousehN,etal.(January2006)."Tandemchimerismasameanstoincreaseproteincomplexityinthehumangenome"(https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1356127).GenomeRes.16(1):3744.doi:10.1101/gr.4145906(http://dx.doi.org/10.1101%2Fgr.4145906).PMC1356127(https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1356127).PMID16344564(https://www.ncbi.nlm.nih.gov/pubmed/16344564).
-
1/15/2015 GeneWikipedia,thefreeencyclopedia
http://en.wikipedia.org/wiki/Gene 16/17
Bibliography
Dawkins,Richard(1990).TheSelfishGene.OxfordUniversityPress.ISBN0192860925.GoogleBookSearch(http://books.google.com/print?id=WkHO9HI7koEC)firstpublished1976.Dawkins,Richard(1995).RiverOutofEden.BasicBooks.ISBN0465069908.Ridley,Matt(1999).Genome:TheAutobiographyofaSpeciesin23Chapters.FourthEstate.ISBN0007635737.Guerzoni,McLysaght,D,A(November10,2011).DeNovoOriginsofHumanGenes.(http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1002381).PLoSGenet7(11).HartwellL,HoodL,GoldbergML,ReynoldsAE,SilverLM,VeresR(2004).Genetics:fromgenestogenomes(Seconded.).Boston:McGrawHillHigherEducation.ISBN0072919302.
Externallinks
ComparativeToxicogenomicsDatabase(http://ctdbase.org/)DNAFromTheBeginningaprimerongenesandDNA(http://www.dnaftb.org/)GenesAndDNAIntroductiontogenesandDNAaimedatnonbiologist(http://www.bioinformaticstutorials.com/?p=6)EntrezGeneasearchabledatabaseofgenes(http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene)IDconverterconvertsgeneIDsbetweenpublicdatabases(http://idconverter.bioinfo.cnio.es/)iHOPInformationHyperlinkedoverProteins(http://www.ihopnet.org/UniPub/iHOP/)TranscriptomeBrowserGeneexpressionprofileanalysis(http://tagc.univmrs.fr/tbrowser)TheProteinNamingUtility,adatabasetoidentifyandcorrectdeficientgenenames(http://www.jcvi.org/pnutility)Genes(http://www.mdpi.com/journal/genes/)anOpenAccessjournalIMPC(InternationalMousePhenotypingConsortium)(http://www.mousephenotype.org/)EncyclopediaofmammaliangenefunctionGlobalGenesProject(http://www.globalgenes.org/)Leadingnonprofitorganizationsupportingpeoplelivingwithgeneticdiseases
31. ^KapranovP,DrenkowJ,ChengJ,etal.(July2005)."ExamplesofthecomplexarchitectureofthehumantranscriptomerevealedbyRACEandhighdensitytilingarrays"(https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1172043).GenomeRes.15(7):98797.doi:10.1101/gr.3455305(http://dx.doi.org/10.1101%2Fgr.3455305).PMC1172043(https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1172043).PMID15998911(https://www.ncbi.nlm.nih.gov/pubmed/15998911).
-
1/15/2015 GeneWikipedia,thefreeencyclopedia
http://en.wikipedia.org/wiki/Gene 17/17
ENCODEthreadsExplorer(http://www.nature.com/encode/#/threads/characterizationofintergenicregionsandgenedefinition)Characterizationofintergenicregionsandgenedefinition.Nature(journal)
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