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1、英语高二下人教版新课标选修8Unit2第6课时教案（文化背景知识）I.Readingcomprehension:Hello,Dolly!Britishscientistshavedonesomethingthatmanypeoplethoughtwasimpossible:theycreatedthefirstcloneofanadultmammal.Theclone,namedDolly,isaseven-month-oldsheep,grownfromacellofanadultfemalesheep.Whatisaclon
2、e?Acloneisacopy,ageneticcopy.Genesaretheinstructionsforlife.Theytellacellwhattodoandhowtodoit.Genesmakeeachindividualplantoranimaldifferentandunique.Butaclonehasthesamegenesastheoriginalorganism.Cloningisnotnew.Plantshavebeenclonedforcenturies.Newplantsareoftengrownf
3、romcuttingsfromanotherplant.Also,plantslikepineapples,strawberriesandcarnationsaresometimescloned.Onebenefitofcloningisthatwecanmakemanycopiesofthebestandhealthiestplants.Ithasbeenmuchmoredifficulttocloneanimals.Frogshavebeencloned,buttheydiedastadpoles,neverlivinglo
4、ngenoughtobecomeadultfrogs.Mice,sheepandcattlehavebeenclonedfromembryos.ButDollyisthefirsthealthycloneofanadultmammal.Howdidtheydoit?(1)Anunfertilizedeggwastakenfromasheep.(2)Theeggnucleuswasremoved.(3)Acellwastakenfromtheudderofapregnantsheep.Itwas“starved”,sothatit
5、stoppedgrowing.(4)Thetwocellswerecombinedintooneandthenimplantedinathirdsheep,whereitgrewnormally.(5)Theclonewasborn.Itwasgeneticallyidenticaltothepregnantsheepinstep(3).Thissoundsmucheasierthanitactuallywas.Toendupwithoneclone,thescientistsstartedwith277uddercells.A
6、ndtheyneededinawaytomaketheeggcellacceptanewnucleus.Theydidthatbystarvingthecellinstep(3).Itmaysoonbepossibletoclonemanytypesofanimals.Willwealsobeabletoclonehumanorgans,orevenwholehumanbeings?Wehaveonlybeguntothinkaboutthemoralityofcloningtechnology.Maybethequestion
7、toaskisnotwhetherwecanclonehumans,butinstead,shouldweclonehumans?1.Dollyisasheepbecausesheisgrownfromacellofanadultfemalesheep_____.A.thathasnotherfatherB.thathasnothermotherC.thathasnoparentsD.thathasnotanytail2.TellwhichofthefollowingstatementsisTRUE.A.Onlyplantsca
8、nbecloned.B.Onlystrawberriesandcarnationscansometimesbecloned.C.Animalsandplantshavequitealonghistoryofcloning.D.Genescantellacellw
