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InheritancePrinciples

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HumanGeneticsBioH-Chapter11GeneticsVocabularyReviewGenes–unitsofinformationaboutheritabletraitsHomologouschromosomes–similarchromosomesreceivedfrommaleandfemalethatlineupnexttoeachduringMetaphaseIinmeiosisAlleles–differentformsofageneLocus–locationonachromosomewherespecificgenesarefoundLinkage–whengenesonachromosome“staytogether”evenduringcrossing-overGeneticrecombination–the“recombining”ofgenesasaresultofcrossing-overChromosomesThomasHuntMorganStudiedfruitfliesFoundXandYchromosomesKaryotypesKaryotypingisaprocessthatallowschromosomestobepresentedinanorderly,easilycomparedmannerSexchromosomes(X,Y)Containgenesthatdeterminethesex(gender)ofanindividualAutosomesNotdirectlyinvolvedindeterminingthesexofanindividualDifferentorganisms,differentnumberXYSexdeterminationSpermhasequalchanceofreceivingXorYEggonlyreceivesXXX–femaleXY-maleTotallyRANDOM processSex-determinationRegionY(SRY)FoundinmammalianYchromosomeGenecodesproteintocause

gonadstodeveloptestesGenelocationSex-linkedTraitscodedforbyanalleleonasexchromosomeCouldbeonXorYchromosomeMoreX-linkedgenesbecauseXismuchlargerIfmalecarriesarecessivealleleontheXchromosome,itwillexhibitthetraitEx.Hemophilia(blooddisorder)LinkedgenesTraitsthatareinheritedtogetherMakesalinkagegroupThishappensbecausetheyarefoundclosetoeachotherinthesamechromosomeandnotaseasilygeneticallyrecombinedby“crossing-over”ChromosomeMapAdiagramthatshowsthelinearorderofgenesonachromosomeMapunit–frequencyofcrossingoverof1%.MutationsGerm-cellmutationsOccuringametes(maynotbeexpresseduntiloffspring)Somatic-cellmutationsOccurinbodycellsMayaffectorgansSkincancerandleukemiaLethalmutationsCausedeath,oftenbeforebirthInheritanceofTraitsPedigreesAdiagramshowinghowatraitisinheritedoverseveralgenerationsRussianRoyalFamily&hemophiliaGeneticabnormality–rare,uncommontraitversionGeneticdisorder–inheritedconditioncausingmedicaldisordersSyndrome–recognizedsetofdisordersthatcharacterizeadisorderPatternsofInheritanceIfatraitisAutosomalAppearsinbothsexesequallyDominantEveryindividualwiththetraitwillhaveparentswiththetraitBBorBb(dominanttraitwillshow)bb(recessivetraitwillshow)Recessive1,2,ornoparentwiththetraitBbXBbwillnotshowmutationbutcanproducechildrenfortherecessiveallele(bb)Bb(carrier)GeneticTraitandDisordersSingle-AlleletraitsControlledbyasinglealleleofageneMore200humantraitsHuntington’sdiseaseForgetfulnessandirritabilityGeneInheritance&DisordersPolygenicInheritanceTraitsareinfluencebymorethanonegeneSkincolor3to6genesGenescontrolamountofmelaninEyecolor,height,haircolorComplexcharactersInfluencedbothbyenvironmentandgenesSkincolor,breastcancer,heightMultipleAllelesGeneswith3ormoreallelesABObloodgroupsIA,IB,andIIAandIB

arecodominantCodominanceBothallelesareexpressedIAIB

istypeABIncompletedominanceTraitthatisdisplayedisintermediatebetweenthetwoparents.HairtypeCurly(CC)XStraight(cc)=Wavyhair(Cc)X-linkedGenesarelinkedtox-chromosomeColorblindnessRecessiveUnabletodistinguishcertaincolors,eg.greenorredSex-influencetraitsMalesandfemalescanshowdifferentphenotypesevenwithsamegenotypesAutosomalTypeofBaldnessDominantinmalesRecessiveinfemalesChromosomaldisordersChromosomeproblems,notgenesDuplication–arepeatof severalgenesequencesonthesamechromosomeDeletion–lossofachromosomesegmentInversion–genesequenceseparatedfromchromosome,reinsertedintosameplace,butinreverseTranslocation–transferofonechromosomeparttoanon-homologouschromosomeChromosomenumberdisordersNondisjunction–oneormorepairsofchromosomesfailtoseparateduringmitosisormeiosis(producesconditionknownasaneuploidy–moreorlesschromosomesthantheparentalnumber)DownSyndrome–oneextrachromosomeat#21SexChromosomenumberchangesTurnersyndrome–inheritingonlyoneXchromosomewithnoadditionalXorYchromosomeMostX0zygotesspontaneouslyabort

0.01–0.04%offemalesNon-functionalovaries(infertile)ShortheightNormalintelligenceKleinfelterSyndrome–oneextraXchromosomewithnormalXY(XXY)0.05-0.2%ofmalesConditionsdevelopafterpubertySmallertestes-usuallysterile(notalways)TallerthannormalNormalintelligenceVerysubtlephenotypecharacteristicsXYYCondition–extraYchromosomeasresultofnon-disjunction0.1%ofmalesTallerthanaverageMildretardationDetectionAmnioncentesisRemovalofamnioticfluidfromtheamnion,thesacsurroundingthefetusBetween14–16weekofpregnancyChorionicvillisamplingCellsderivedfromthezygotethatgrowbetweenuterusandplacentaBetween8thand10thweekGeneticcounselingInformingapersonorcoupleabouttheirgeneticmakeupFor