选修八Unit-2cloning-Period-1-Reading-ppt课件-(41张)-高中英语-人教版VIP专享VIP免费

CloningUnit2cloningstrawberrydiffern.克隆；无性繁殖系vi&vt.（使）无性繁殖；克隆n.草莓vi.不同；相异WordspreviewAcloneisananimalorplantproducednaturallyorartificiallyfromthecellsofanotheranimalorplantandisexactlythesameasit.Cloningisawayofmakinganexactcopyofanotheranimalorplant.TheclonehasthesameDNAastheparent.What’scloning?SoundsReasonable?Therearedifferenttypesofcloning,andcloningtechnologiescanbeusedforotherpurposesbesidesproducingthegenetictwinofanotherorganism.Thethreetypesofcloningtechnologiesare:(1)recombinantDNAtechnologyorDNAcloning（基因重组克隆技术）(2)reproductivecloning（再生克隆技术）(3)therapeuticcloning（干细胞疗法克隆技术）克隆一词是英文单词clone的音译,作为名词,clone通常被意译为无性繁殖系。同一克隆的所有成员的遗传构成是完全相同的,例外仅见于有突变发生时。自然界早已存在天然植物、动物和微生物的克隆,例如：同卵双胞胎实际上就是一种克隆。然而,天然的哺乳动物克隆的发生率极低,且缺乏目的性,所以很少能够被用来为人类造福。因此,人们开始探索用人工的方法来生产高等动物克隆。这样,克隆一词就开始被用作动词,指人工培育克隆动物这一动作。目前,生产哺乳动物克隆的方法主要有胚胎分割和细胞核移植两种。克隆羊“多莉”,以及其后各国科学家培育的各种克隆动物,采用的都是细胞核移植技术。所谓细胞核移植，是指将不同发育时期的胚胎或成体动物的细胞核，经显微手术和细胞融合方法移植到去核卵母细胞中，重新组成胚胎并使之发育成熟的过程。由于细胞核移植是产生克隆动物的有效方法，故人们往往把它称为动物克隆技术。Inpairs,lookatthesepicturesanddiscusswhichonesarenaturalclonesandwhichonesareman-made.Thinkabouthowtheydiffer.QuizDollythesheepAstrawberryplantNaturalcloneMan-madeclone一株草莓依靠它沿地“爬走”的匍匐茎,一年内就能长出数百株草莓苗。GrowingnewplantsTwinsNaturalcloneMan-madecloneNaturalcloneisonethatoccursinnaturewithouthumanhelp.Man-madecloneisonethatisproducedthroughhumanintervention(介入).CloneCanyoutellthedifferencebetweennaturalcloneandman-madeclone?Cactus(仙人掌)Pendulumorchid(吊兰)naturalcloneexamplesman-madecloneexamplesI'mcelebrityinthehistoryofcloning.Doyouknowmyname?Dolly,thefirstmammaltobeclonedfromadultDNA,wasputdownbylethalinjectiononFeb.14,2003.Priortoherdeath,Dollyhadbeensufferingfromlungcancerandcripplingarthritis(严重的关节炎).CelebritySheepDollyDolly是世界上第一例用体细胞─乳腺上皮细胞,通过细胞核移植技术,在复杂的人工操作下,得到的一只小绵羊。Scientistshavebeencloninganimalsformanyyears.ThecreationofDollyisthefirstmammalclonedfromthecellofanadultanimal.SinceDolly,researchershaveclonedanumberoflargeandsmallanimalsincludingsheep,goats,oxen,mice,pigs,cats,rabbitsandsoon.Allthesecloneswerecreatedusingnucleartransfertechnology（细胞核移植技术）.Whatanimalshavebeencloned?2002年4月16日美国第一头克隆牛“艾米”产下牛犊喜作妈咪。2002年5月中旬成功地繁殖了一只胚胎细胞克隆兔。第一只克隆猫克隆马及其“母亲兼姐姐”克隆的荧光小猪(左)和正常小猪(右)ImportanteventsincloninghistoryIn5000B.C.(谷物选种)Humanbeingsbegantochoosethebestseedsfromsomekindsofcrops.Thatwasthebeginningofcontrollinglifeaccordingtohuman’swill.In1952:Cloningtadpole(克隆蝌蚪)TheAmericanscientistscreatedacopyoftadpolebymeansofusingatadpolecell.Thistinytadpolehasbecomethefirstkindofcloninganimal.In1978:Thefirstcaseoftubeinfant(试管婴儿)appeared.☆ABritishdoctorusedthesperm(精液)ofamanandfertilized(受精)itinatesttube(试管)andthentransplanted(移植)theembryo(胚胎)intothewomb(子宫)ofahealthymother.☆ThefirsttubeinfantcalledLouisappeared.Dollyand...