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1、河北省武邑中學(xué)2016屆高考英語(yǔ)一輪復(fù)習(xí)Unit2Cloning導(dǎo)學(xué)案新人教版選修8ReadingCLONING:WHEREISITLEADINGUS?Cloninghasalwaysbeenwithusandisheretostay.Itisawayofmakinganexactcopyofanotheranimalorplant.Ithappensinplantswhengardenerstakecuttingsfromgrowingplantstomakenewones.Italsohappensinanimals1.________twinsidenticalinsexandapp
2、earanceareproducedfromthesameoriginalegg.Thefactisthatthesearebothexamplesofnaturalclones.Cloninghastwomajoruses.Firstlygardenersuseitallthetimetoproducecommercialquantitiesofplants.Secondly,itisvaluableforresearchonnewplantspeciesandformedicalresearchonanimals.Cloningplantsisstraightforward2.____
3、___cloninganimalsisverycomplicated.Itisadifficulttask3.______________(undertake).Manyattemptstoclonemammalsfailed.Butatlastthedeterminationandpatienceofthescientistspaidoffin1996withabreakthrough—thecloningofDollythesheep.Theprocedureworkslikethis:1.FemalesheepAprovidesaneggcell.2.Thenucleusisremo
4、vedfromtheeggcell.3.Theeggcellisreadyforanewnucleus.4.FemalesheepBprovidesasomaticcellfortheclone.Thenucleusofthiscellcontainsallthegenesneededtoproduceanewsheep.5.Thenucleusistakenoutofthesomaticcell.6.ThenucleusfromsheepBandtheeggcellfromsheepAarejoinedusingelectricity.7.Thecelldividesandgrowsin
5、toanembryo.8.TheembryoisputintofemalesheepC,whobecomesthecarrieroftheclone.9.ThelambisthecloneofthedonatedcellfromSheepBwhichprovidedthenucleus.Ontheonehand,thewholescientificworldfollowedtheprogressofthefirstsuccessfulclone,Dollythesheep.Thefactthatsheseemedtodevelopnormallywasvery4._____________
6、(encourage).Thencamethedisturbingnews5.__________Dollyhadbecomeseriouslyill.Cloningscientistswerecastdown6._________(find)thatDolly’sillnessesweremoreappropriatetoamucholderanimal.AltogetherDollylivedsixandahalfyears,halfthe7.________(long)ofthelifeoftheoriginalsheep.8._________[盡管]herproblems,Dol
7、lysuccessfullyproducedalambina9.___________(nature)birth.Sadlythesamearbitraryfateaffectedotherspecies,suchasclonedmice.Thequestionsthatconcernedallscientistswere:“Wouldthisbe10._____majordifficultyforallclonedan
