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Part6.4
1Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
Storycard
PeterandhisfamilyliveonasmallfarminWesternAustralia.Peterworkslonghoursonthefarm,sixtosevendaysaweek,makingamodestincometosupporthisfamily.InaddiAontoseveralothercrops,Peterhasbeengrowingcanolaonhisfarmforthelast10years(canolaisaplantthatisgrownforitsoil,whichisusedinproductslikemargarineandcookingoil).Hiscanolacropshavebeenaffectedbyweedsthough,whichhavereducedhisyields.PeterbaHlesweedsinhiscanolacropsbysprayingthemwitharangeofcostlyherbicides.Heworriesabouttheeffectoftheseherbicidesontheenvironment.Peter’sfriend,Geoff,farmsgeneAcallymodified(GM)canolathathasbeenmodifiedtoberesistanttoaparAcularherbicide.Thisherbicidekillsarangeofdifferentweeds,soGeoffcansprayhiscropswithfewerherbicidestokillweeds,withoutaffecAnghiscanolaplants.PeterwantstotrygrowingGMcanola,becausehethinksitwillmakethecropseasiertomanageandincreasehisyields.Hisdaughter,Leah,isunsureaboutherdad’sideatotrygrowingGMcanola,itmightmakelifeeasier,butherfriendssayGMcropsareunsafeandcontrolledbylargemoney-grabbingcompanies.Peter’sneighbour,Sally,whoisanorganicfarmer,hastoldhimheshouldn’tgrowunnaturalGMcropsthatcouldcontaminateherfarm.
ShouldPetertrygrowingGMcanola?
2Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
Doweknowenoughaboutthesafetyof
GMfoodstobeeaAngthem?
Issuecard
AreGMplantsgoodnewsorbadnews
fortheenvironment?
Issuecard
DowereallyneedGMcrops?
Issuecard
DoGMplantsbenefitsmallfarmers,oraretheyjustatoolforlargecompanies
tomakemoney?
Issuecard
3Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
ShouldPeterhavetherighttogrowGM
plantsnexttoanorganicfarm?
Issuecard
Issuecard
Isitrighttointerferewithnature
bymovinggenesbetweenspecies?
4Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
ControllingweedsincanolaWeedsaffectcanolacropsbycompeAngfornutrients,sunlightandwater.Farmerscanreduceweedsmechanically(byAlling),butthisdegradesthetopsoil.ToreducetheneedforAlling,manyfarmersuseherbicidestokillweeds.WithconvenAonalcanola,theyapplyherbicidebeforeplanAng,toclearthefieldofweeds.Later,thegrowingcropisoWensprayedwithadifferentherbicidetoremoveclover,thistlesandcapeweed.Grassyweedsarecontrolledbydifferentherbicidesagain.
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GMcrops:BenefitstotheenvironmentOnetypeofGMcanolaallowsfarmerstousethebroadspectrumherbicideglyphosate(Roundup®).GlyphosateisbeHerfortheenvironmentthanmanyoftheherbicidesitreplaces,becauseitislesstoxicandlesslikelytocontaminatewaterwaysandsoils.Becausebroadspectrumherbicidesremoveabroadrangeofweeds,farmersgrowingGMcanolacanusefewerherbicides.
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GMcrops:Benefitstotheenvironment(side2)
GMcanolareducestheneedforAllingpriortoplanAng.AreducAoninAlling,helpstoprotectsoilsfromerosion,nutrientandwaterloss.Onaglobalscale,GMcropshavereducedpesAcideuse,CO2emissions,andlandclearingforagriculture(duetoincreasedyields).
Controllingweedsincanola(side2)Broadspectrumherbicidesareherbicidesthatkillabroadrangeofweeds.Theycan’tnormallybeusedongrowingcanolacrops,becausetheyalsokillcanola.GMcanolahasbeendevelopedtoberesistanttoparAcularbroadspectrumherbicides.Beingabletouseoneherbicidetokillarangeofweedsinthegrowingcrop,meansfarmerscanreducetheirherbicideuse.
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5Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
HowcommonareGMcropsinAustralia?• TheonlycommerciallygrownGMcropsin
AustraliaarecoHonandcanola.• Pestand/orherbicide-resistantGMcoHon
hasbeengrowninAustraliasince1996,andherbicideresistantGMcanolasince2008.
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GenesMostoftheDNAincellsispackagedintochromosomes.GenesarearrangedalongthesechromosomesandcarrytheinstrucAonstomakemolecules,suchasproteins.TofuncAonproperly,eachcelldependsonthousandsofproteinsdoingtherightjob,intherightplace,attherightAme.
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Genes(side2)Aplant’scompletesetofDNA,containingalltheinstrucAonsrequiredtomakeit,iscalleditsgenome.
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HowcommonareGMcropsinAustralia?(side2)GMcarnaAonplantsthatweredevelopedfortheirbluecolour(byacompanyinMelbourne)arecommerciallyavailableinAustralia.
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6Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
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GMcrops:Effectsontheenvironment
Somegroupsareconcernedthat:• GMplantscouldcross-breedwithother
plants,transferringgenes(e.g.forherbicideresistance)intoplantsintheenvironment.
• Pest-resistantGMplantsproduceasubstancethatcouldbetoxictonon-targetinsectspeciesandcouldaffectsoilhealth.
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GMcrops:Effectsontheenvironment(side2)
• GMseedscouldescapeintotheenvironment.
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GMtechnology(side2)Inplants,thegeneforadesiredtrait(likepestresistance)canbeinsertedintotheplant’sgenomeusingabacteriumoraminiaturegun.
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7Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
GMtechnologyAgeneAcallymodifiedorganism(GMO)isonethathashaditsDNAsequencechangedbyinserAng(orremoving)agene.
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GMcropsandmulGnaGonalsAreGMplantsjustawayforlargecompaniestocontrolagricultureandmakemoney?Orarecompaniesjus;fiedinexpec;ngareturnontheirinvestmentindeveloping,tes;ngandgeAngapprovalsforGMplants?• FarmersthatgrowGMcropsoWenhavea
contractwiththecompanythatownsthetechnology.ThissetsoutcondiAonsforgrowingtheplants,andrequiresfarmerstobuynewseedeachyear,ratherthanbeingabletosaveseedfromthisyear’scroptoplantnextyear.
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RegulaGngGMcropsinAustralia
GMcropsareregulatedthroughtheCommonwealthGeneTechnologyAct2000andstatelegislaAon.ThisaimstoidenAfyandmanageanyriskswithgenetechnology.FederalapprovalisneededtobeabletoreleaseGMplantsinAustralia.ThedecisiononwhethertoallowGMcropstobegrown,isuptoindividualstates.TasmaniaandtheACT,forexample,don’tallowcommercialGMcrops.
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RegulaGngGMcropsinAustralia(side2)
AllgeneAcallymodified(GM)foodsmustbeassessedforsafetybyFoodStandardsAustraliaNewZealand(FSANZ).FoodsfromGMcropsmustbelabelledwiththewords“geneAcallymodified”,togivepeopleachoiceinwhattheyeat.
InformaGoncard
GMcropsandmulGnaGonals(side2)• Somenon-profitorganisaAonsprovideGM
technologyforfree,suchasGMplantsthatarerichinnutrientsforpeopleindevelopingcountries.
• GMcropsbenefitbothsmall-andlarge-scalefarmers.In2013,over90%offarmerswhochosetogrowbiotechcrops,weresmall,poorfarmersindevelopingcountries.
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8Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
GMcrops:AgriculturalbenefitsGMcropscan:• reducepestsandweeds• reducepesAcideuse• increaseyieldsandprofits• reduceplantdiseases
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GMfoodsafetyToxicityandallergensSomepeopleareconcernedthatinserAngnewgenesintoplantcells,couldlettheplantproduceproteinsthataretoxic,orcauseanallergicreacAon.Beforetheyareapproved,GMfoodsarecarefullyassessedfortoxinsandallergens.Naturallyoccurringallergens(suchasinpeanuts),canactuallyberemovedfromfoodsthroughgeneAcmodificaAon.NutriAonGMfoodsarenutriAonallycomparabletotheirnonGMcounterparts,ifnotbeHer.Forexample,AustraliaisdevelopingGMbananasthatarehighinvitaminA,tohelpfightvitaminAdeficiencyindevelopingcountries.
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GMfoodsafety(side2)
AnAbioAcresistanceSomepeopleareconcernedthatGMfoodcouldtransferanAbioAcresistancegenestobacteriainourbodies,makingdiseaseshardertotreatwithanAbioAcs.AWernumerousstudies,theWorldHealthOrganizaAonandtheEuropeanCommissionhaveconcludedthatfoodsfromGMcropsareassafeasconvenAonalfoods.
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GMcrops:Agriculturalbenefits(side2)GMcropscan:• reducemanagementcosts• reducetheneedforAlling,whichcan
degradesoilquality• allowcropstobegrowninpoorcondiAons
(e.g.lowwater,highsalinity)
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9Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
GrowingGMcropsnearorganicfarmsAnorganicfarmerinWesternAustralialosthisorganiccerAficaAonwhenGMmaterialwasfoundonhisproperty.In2014,hesuedhisneighbour,aGMfarmer.LawyersfortheorganicfarmersaidthattheGMseedsshouldhavebeencontainedbeHer,whiletheGMfarmermaintainedthattheorganiccerAficaAonprocesswasunreasonable.
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Socialandethicalissues
InformaGoncard InformaGon
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GrowingGMcropsnearorganicfarms(side2)TheWASupremeCourtruledthattheGMfarmercouldnotbeheldresponsibleforgrowingalegalGMcropinaconvenAonalway.
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AnG-GM Pro-GM
• Somebelieveitisn’trighttointerferewithnaturebychanginganorganism’sgenes.
• GlobalfoodshortagesarecausedmorebyeconomicsandpoliAcs,thanbyfarmproducAon.
• LargecompaniescoulddominateglobalagriculturethroughGM.
• TradiAonalbreedinghasbeenselecAngfordesiredgenesforthousandsofyears.
• Genesaretransferredbetweendifferentspeciesinthenaturalenvironment.
• GMcropsbenefitbothsmallandlarge-scalefarmers.
Socialandethicalissues(side2)
AnG-GM Pro-GM
• GMfood(e.g.withpigDNA)couldcreateproblemsforsomereligiousgroups(thereisnoconsensuswithinthemajorreligionsregardingGM).
• GMfoodcanhelptoalleviatehunger,improvenutriAonandbenefitmankind.
• PeoplearegiventherighttochoosewhethertobuyGMproductsinAustraliathroughlabelling.
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10Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
CanolaCanolaisamemberoftheBrassicaceaefamily,whichalsoincludescabbages,broccoliandcauliflower.Itisgrownforitsseeds,whicharerichinoil.Canolaoilisusedinfoodproductslikemargarineandcookingoil.TheseedmaHer,leWaWerextracAngtheoil,isusedinstockfeed.
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Globalfooddemand
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Globalfooddemand(side2)
IncreasedproducAontomeetglobalfooddemand,shouldcomefromincreasingyields,notfromincreasingtheareaofagriculturalland.Clearinglandforfarminghasenvironmentaleffects,includinggreenhousegasemissionsandlossofbiodiversity.
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Canola(side2)
CanolawasfirstgrowninAustraliain1969,withproducAonrapidlyexpandinginrecentyearstobecomeoneofourmostimportantcrops,worth$2.3billionin2012-13.
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11Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
StorycardAngiewillneverbeabletowalk.ShewasbornwithSpinalMuscularAtrophy(SMA),ageneAccondiAonthatresultsinmusclewasAng.Angiereliesonhermumanddadtodoeverydaythingslikegelnginandoutofbed,goingtothebathroomandgelngdressed.Shehasproblemsbreathingatnight,anddoctorshavetoldherparents,GabbyandPhil,thatshemightnotlivebeyondherteenageyears.GabbyandPhilwanttohaveanotherchild,butareworriedbecausetheyhaveaoneinfourriskofhavinganotherchildwithSMA.Gabby’sdoctorhassuggestedthattheyconsideramedicaltechniquecalledPGD,whichcouldhelpthemhaveachildwithoutthecondiAon.PGDinvolvestesAngembryosforgeneAcdisordersbeforetheyareimplantedinthemother’suterus.GabbyandPhilwouldlovetomakesuretheirnextchilddoesn’thavetosufferlikeAngiehas,butGabbyisworriedthatusingPGDmightmakeAngiefeelunwanted.Phil’ssister,Beth,thinksitwouldbewrongtochoosethefeaturesoftheirbaby,shebelievesGabbyandPhilshouldleavethingstonature.
ShouldGabbyandPhilusePGDtohaveababywithoutspinalmuscularatrophy?
12Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
WhoshouldberesponsibleforallowinggeneActesAngofembryos?Theparents,
doctorsortheGovernment?
Issuecard
IsitfairthatPGDisonlyaccessibletopeoplelikePhilandGabbywhocanafford
it?
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HowwouldembryoselecAontoavoidageneAcdisordermakepeoplelikeAngie,whoarelivingwiththedisorder,feel?
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CouldPGDeventuallyleadtoacceptanceof‘designerbabies’thatareselectedfor
featureslikephysicalappearance?
Issuecard
13Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
IsitwrongforPhilandGabbytochoose
thefeaturesoftheirbaby?ShouldPhilandGabbyhavetherighttopreventdevelopmentofababythatwill
sufferwiththedisorder?
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Issuecard
IsIVFwithPGDworththerisktothe
embryo?
14Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
WhatisPGD?
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EthicalissueswithembryoselecGon• Onlyavailabletothosewhocanpayforit.• Somepeoplethinkitiswrongtochoosethe
featuresofababy.• ByselecAngagainstadisorder,itcould
creatediscriminaAonissuesforpeoplelivingwiththatdisorder.
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EthicsofembryoselecGon(side2)• Couldleadtoacceptanceof‘designer
babies’thatarechosenfornon-healthcharacterisAcse.g.intelligence,athleAcability,height,haircolour.
• SomepeoplethinkitiswrongtodiscardunwantedembryosfromPGD.
• whatcountsasaseriousgeneAccondiAonisunclear.
WhatisPGD?(side2)
PGDstandsforpreimplantaAongeneAcdiagnosis.ThistechnologyallowsparentstoselectforparAcularcharacterisAcsintheirchildren,usuallytoavoidcertaingeneAcdisorders.InPGD,embryosareproducedoutsidethemother’sbody(throughIVF).Theyarethentestedforthedisorderandonly‘healthy’embryosareimplantedinthemother’suterus.
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15Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
WhatisIVF?IVFstandsfor‘invitroferAlisaAon’.ItisatechniquethatisusedtohelpcoupleswithferAlityissuestohavechildren.InIVF,eggsandspermarecombinedoutsidethewoman’sbody(invitro–inaglassdish)tocreateanembryo.
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UsesofPGDPGDcanbeusedtohelpparentswithafamilyhistoryofageneAcdisordertohavechildrenwithoutthedisorder:• byselecAngembryosofonesex,whenthe
disorderonlyaffectsmalesorfemales.• bytesAngembryosforgenesthatcausea
seriousgeneAcdisease(e.g.cysAcfibrosisorspinalmuscularatrophy).
• bytesAngforgenesthatcanincreasetheriskofgelngadiseaseordisorder(e.g.breastcancer).
Insomecountries,couplescanchoosethesexoftheirbabyfornon-medicalreasons.
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UsesofPGD(side2)
PGDhasalsobeenusedbysomecouplestocreateachildthatcanbeabloodorAssuedonorforasicksibling.AlternaAvediagnosismethods(likeultrasound),testfordisordersduringpregnancy.Ifthetestshowsthedisorder,parentsmaybefacedwiththedifficultdecisionofwhetherornottoterminatethepregnancy.PGDavoidsthisdilemmabytesAngforadisorderbeforepregnancy.
WhatisIVF?(side2)Embryosaregrowninthelaboratoryovertwotofivedays,beforebeingtransferredintothewoman’suterus.
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16Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
SuccessratesLikeIVF,thesuccessofPGDcan’tbeguaranteed.Problemscanoccurateachstepintheprocess.ThegraphbelowshowsthesuccessrateinAustralia(in2011)fromatotalof1182casesofPGD.
CostsofPGDTherearelargeout-of-pocketcostsforIVFwithPGDinAustralia:• IVFpercycle $3000-$4000
(aWerMedicarerebate)• PGD upto$4000
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CostsofPGD(side2)CostsvarydependingontheclinicandthegeneActest.PGDiscurrentlyonlyavailableinprivateclinics,withnoMedicarerebate.Manycouplesgothroughseveralcyclesbeforetheyhaveasuccessfulpregnancy,mulAplyingthetotalcost.
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Source:UNSW2013
17Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
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RegulaGngPGDinAustralia.• PGDisnotregulatedbyfederallaw.• Tobeaccredited,clinicsmustfollow
guidelinessetoutbytheNaAonalHealthandMedicalResearchCouncil.
• SexselecAonisonlyallowedifitwillreducetheriskofaseriousgeneAccondiAon.
.
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Spinalmuscularatrophy(SMA)SMAisageneAccondiAonaffecAngthenervesthatcontrolmovementofmuscles.Thiscausesmuscleweaknessandcanleadtoproblemswithbreathing,swallowingandwalking.SMAisclassifiedintotypes,dependingonitsseverity.BabieswithSMAtype1usuallydiebytheageoftwo.Peoplewithtype2usuallycan’twalkorstandwithoutassistance,andhaveareducedlifeexpectancy.AlthoughpeoplewithSMAtype3and4areaffectedphysically,theyhaveanormallifeexpectancy.
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Spinalmuscularatrophy(side2)
SMAiscausedbyarecessivegene,sopeoplewiththecondiAonhaveinheritedtwocopiesofthefaultygene(onefromeachparent).Ifbothparentsarecarriers,theyhaveaoneinfourchanceofhavingachildwithSMA.
RegulaGngPGDinAustralia(side2)StateandterritorylegislaAonvaries.Insomestates,suchasVictoria,PGDisdirectlyaddressedbylegislaAon,whileothersrelyonthenaAonalguidelines.
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18Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
GenesMostoftheDNAincellsispackagedintochromosomes.GenesarearrangedalongthesechromosomesandcarrytheinstrucAonstomakemolecules,suchasproteins.TofuncAonproperly,eachcelldependsonthousandsofproteinsdoingtherightjob,intherightplace,attherightAme.
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ThealternaGvesForcoupleswhoareatriskofhavingababywithaseriousgeneAcallyinheritedcondiAon,theiropAonsareto:• nothavechildren• riskhavingababywiththecondiAon• usediagnosActesAngtoavoidhavingababy
withthecondiAon
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ThealternaGves(side2)
DiagnosActesAngcanbedone:• duringpregnancyusingultrasoundorby
geneActesAng.IfresultsareposiAve,thecouplemaythenfacethedifficultdecisionofwhethertoterminatethepregnancy.
• beforepregnancyproceeds,bycreaAngembryosoutsidethebodyandusingPGDtoonlychoosethosewithoutthecondiAon.
Genes(side2)Anorganism’scompletesetofDNA,containingalltheinstrucAonsrequiredtomakeit,iscalleditsgenome.
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19Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
Amyisjust15.HerfamilyhasbeenrockedbytherecentnewsthatAmy’sAunAeLindahasbreastcancer.Amy’sfatherMarkisespeciallyworriedabouthissisterLinda.MarkandLindalosttheirmothertobreastcancershortlybeforeAmywasborn.AgeneActesthasrevealedthatAunAeLindahasamutaAonofherBRCA1gene,whichincreasesaperson’sriskofdevelopingbreastcancer.AmywantstoknowifshealsohastheBRCA1mutaAon,butthestandardprocedurewouldbetotestherfatherMarkfirsttoseeifhehastheBRCA1mutaAon.IfthisisconfirmedAmycouldthenhavethetest,asthereisevidencethatadirectrelaAvecarriesthemutaAon.MarkiswillingtobetestedbutAmy’smother,Julia,isagainstit.JuliathinksAmyistooyoungandisconcernedabouthowAmywouldreactifshefoundoutshewasatriskofhavingtheBRCA1mutaAon.MarkwillonlydothetestifJuliaandAmycancometosomeagreement.Amyleadsahealthylifestyle–eaAnghealthilyandexercisingregularly–butsheiswillingtodoanythingtoavoidgelngbreastcancer.(cardsadaptedfromGenomeGenera;on,GenomeResearchLtd)ShouldAmyinsistonherfatherMarkbeingtestedfortheBRCA1mutaGon?
Storycard
20Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
IsitbeHertofindoutasearlyaspossibleorisAmytooyoungtocopewiththistypeofinformaAon?
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IfMarktakesthetest,whoshouldhaveaccesstohisresults?
Issuecard
IfAmydiscoversshemaybeatrisk,whatshouldshedonext?Forexample,shouldshehavethetestfortheBRCA1mutaAonherself?
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IfMarkdiscoversthathedoesnothavetheBRCA1mutaAon,howwillthatimpactAmyandtherestofthefamily?WhatdoesAmygainfromknowingthatinformaAon?
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21Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
ShouldthistestbefreelyavailabletoeveryonethroughMedicare?
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IfMarkdiscoversthathedoeshavetheBRCA1mutaAonwhatdoesthatmeanforhim?
22Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
ThegeneGcsofbreastcancerMutaAonsintheBRCA1andBRCA2genesarestronglylinkedtobreastcancerrisk.Theyarealsolinkedtoanincreasedriskofovariancancer.
OurgenesMostoftheDNAinhumancellsispackagedinto46chromosomes,in23pairs.OurgenesarearrangedalongthesechromosomesandcarrytheinstrucAonstomakemolecules,suchasproteins.
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Ourgenes(side2)
TofuncAonproperly,eachcelldependsonthousandsofproteinsdoingtherightjob,intherightplace,attherightAme.OurcompletesetofDNA,containingalltheinstrucAonsrequiredtomakeus,iscalledagenome.
ThegeneGcsofbreastcancer(side2)Fewerthan1in500womencarryahigh-riskmutaAonforbreastcancer.IfapersoncarriesamutatedcopyoftheBRCA1orBRCA2gene,itdoesnotmeantheywilldefinitelydevelopcancer.• WomenwithaBRCA1mutaAonhavea
75-85%lifeAmeriskofdevelopingbreastcancer.
• WomenwithaBRCA2mutaAonhavea50-80%lifeAmeriskofdevelopingbreastcancer.
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23Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
• WomenwithaBRCA1mutaAonhavea75-85%lifeAmeriskofdevelopingbreastcancer.
• WomenwithaBRCA2mutaAonhavea50-80%lifeAmeriskofdevelopingbreastcancer.
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Howcommonisbreastcancer?1in8womenwillgetbreastcancerbytheAmetheyare85.Becausebreastcancerissocommon,havingmorethanonerelaAvewiththediseasedoesnotnecessarilymeanthatthefamilycarriesahighergeneAcrisk.
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GenemutaGonsAmutaAonisapermanentchangeintheDNAsequence.MutaAonscomeinanumberofdifferentformsandcanchangethefuncAoningofourgenes.
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GenemutaGons(side2)SomemutaAonsmayleadtoadifferenceintheamount,orstructure,ofaproteinproducedbyspecificgenes.SomemutaAonsmayswitchgenesonatthewrongAme,prevenAngaproteinfromdoingitsjob,orchangingthewayitdoesitsjob.
Howcommonisbreastcancer?(side2)Thehighestriskfactor(aWerbeingfemale)isage.77%ofbreastcancersoccurinwomenover50.
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Source:AIHW2014
24Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
BreastcancerstaGsGcs• Breastcanceristhethirdmostcommonly
diagnosedcancerinAustralia,with14,680newcasesin2012.
.
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HealthcareadviceforbreastcancerAllwomen,regardlessoftheirfamilyhistoryorgeneAcrisk,areadvisedto:• examinetheirownbreastsandreportany
changesimmediately• eatahealthydietandkeepfit
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Healthcareadviceforbreastcancer(side2)• maintainhealthyweight,especiallyaWer
menopause• moderatealcoholconsumpAon.
BreastcancerstaGsGcs(side2)• In2009,theriskofbeingdiagnosedwith
breastcancerby85yearsofagewas1in8forfemalesand1in724formales.
• Therewere14,560femaleand120male
deathsfromthediseaseinAustraliain2012.
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Source:AIHW2013
25Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
TumoursuppressorgenesBRCA1andBRCA2areexamplesoftumoursuppressorgenes,whichplayanimportantroleinprevenAngcancer.Normally,ifDNAisdamaged,thesegeneshaltcelldivisionorpromotecelldeath.
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BreastcancerinmenBreastcancerisnotonlyathreattowomen.Mencangetbreastcancer,althoughitismuchrarer,accounAngforlessthan1%ofcasesinAustralia(127newcasesin2010).
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Breastcancerinmen(side2)Lowerawarenessofmalebreastcancermeansittendstobedetectedatalaterstageinmenthaninwomen,whichmeansthattheoutcomestendtobeworse.
Tumoursuppressorgenes(side2)Wehavetwocopiesofeverygene–oneinheritedfromeachparent.InheritanceofjustonecopyofaBRCA1orBRCA2mutaAonfromaparent,isenoughtoincreasetheriskofdevelopingbreastcancer.
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26Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
MonitoringwomenathighriskWomenwithafamilyhistoryofbreastcancerarecategorisedaseither‘raisedrisk’or‘highrisk’.Lessthan1%ofwomenareathighrisk.InAustralia,womenlessthan50yearsofageathighriskofbreastcancermayreceiveyearlyMRI(magneAcresonanceimaging)screeningunderMedicare.MRIusesamagneAcfieldandradiowavestoproducedetailedimagesofthebreastAssue.
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GeneGcscreeninginat-riskfamiliesIngeneAcscreening,alivingrelaAvewithbreastcancerhastobetestedfirst.IftheyhaveoneofthemutaAonsassociatedwiththecancer,otherfamilymemberscanbetestedforthesamemutaAon.
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Breastcancerscreeninginat-riskfamilies(side2)GeneActesAngofunder-16sfordiseasesthatoccurinadulthoodisnotnormallyadvised.InAmy’scase,itwouldbeclinicalpracAcetotestthefather(whohasarelaAvewiththegenemutaAon)first.
Monitoringwomenathighrisk(side2)SomehighriskwomenchoosetoremovealloftheirbreastAssueasaprevenAvemeasure,aprocedureknownasapre-empAvemastectomy.
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27Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
OurDNA
Ourbodiesaremadeupofaround50trillioncells.Mostofthesecellscontainaperson’sgeneAcinformaAonwithinalongmoleculecalledDNA(deoxyribonucleicacid).ThisDNAcontainsthegeneAcinformaAonthatweinheritfromourparents.
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Whatiscancer?
AllcancersaregeneAcdiseases.CancerdevelopsfromsinglebodycellsthatconAnuallydivideinanuncontrolledmanner.Cancercellsbehaveinthisabnormalwaybecauseofchanges(mutaAons)intheDNAsequenceofkeygenes,whichareknownascancergenes.
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Whatiscancer?(side2)
ThechangesintheDNAprovideagrowthadvantagetothecell.Thismeansthatthecancercellanditsoffspringdivideatafasterratethanthatoftheirneighbours.ThisresultsintumourformaAon,invasionofsurroundingAssueand,ifleWuntreated,eventually‘metastasis’wherethecancerspreadstootherpartsofthebody.
OurDNA(side2)DNAismadeupofspecificsequencesofleHersorbasesthatencodeinstrucAonsonhowtomakeproteins.ThefourbasesareAdenine(A),Guanine(G),Cytosine(C)andThymine(T).TheyarelinedupalongtwostrandsofDNAandtheDNAiscoiledintoadoublehelixstructurethatresemblesatwistedladder.
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28Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
WhatistheriskofinheriGngaBRCAmutaGon?ThemutatedBRCA1andBRCA2genesareinheritedinanautosomaldominantpaHern.Thismeansthatachildonlyneedstoinheritonecopyofthemutatedgenetohaveanincreasedriskofdevelopingcancer.
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WhatistheriskofinheriGngaBRCAmutaGon?(side2)
IfoneoftheparentsisacarrierofamutatedBRCA1orBRCA2gene,eachoftheirchildrenhasa1in2(50%)chanceofinheriAngthemutatedgenefromthecarrierparent.
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29Evolution and Heredity • Activity 6.4 Cleverly Used Genes e
TopissuesWhatarethetopissuesthatyouhavediscussedinyourgroup?
30Evolution and Heredity • Activity 6.4 Cleverly Used Genes e