1、,cloing,Whats cloning?,Cloning is the creation of cells or whole animals using DNA(脫氧核糖核酸) from a single parent, bypassing(繞道而行) the normal reproductive process. The clone has the same DNA to the parent. There are different types of cloning, and cloning technologies can be used for other purposes be

2、sides producing the genetic twin of another organism. The three types of cloning technologies are: (1) recombinant DNA technology or DNA cloning（基因重組克隆技術(shù)） (2) reproductive cloning（再生克隆技術(shù)） (3) therapeutic cloning（干細(xì)胞療法克隆技術(shù)）.,-the animal which had been first cloned,celebrity sheep Dolly,Dolly(1996-200

3、3) was a mother to six lambs, bred the old-fashioned way.,Although most Finn Dorset sheep live to be 11 to 12 years of age, postmortem examination of Dolly seemed to indicate that, other than her cancer and arthritis, she appeared to be quite normal. The unnamed sheep from which Dolly was cloned had

4、 died several years prior to her creation. Dolly(1996-2003), the first mammal to be cloned from adult DNA, was put down by lethal injection on Feb. 14, 2003. Prior to her death, Dolly had been suffering from lung cancer and crippling arthritis.,Dolly,What animals have been cloned?,Scientists have be

5、en cloning animals for many years. In 1952, the first animal, a tadpole, was cloned. Before the creation of Dolly, the first mammal cloned from the cell of an adult animal, clones were created from embryonic cells. Since Dolly, researchers have cloned a number of large and small animals including sh

6、eep, goats, cows, mice, pigs, cats, rabbits, and a gaur. All these clones were created using nuclear transfer technology（細(xì)胞核移植技術(shù)）.,Dolly,Cloned monkeys,First cloned mule,Cloned twin goats,First cloned horse,First cloned cats,Cloning(克隆技術(shù)) is the most attractive story of the new biotechnologies(生物技術(shù))

7、 and the one which causes the most heated discussion over its worth.,Here are answers to the most common questions about cloning,Question1: Is cloning unnatural?,Answer: No. Clones are always produced by natural means in the shape of identical twins(同卵孿生).,Answer: The most common process takes DNA f

8、rom one cell and puts in a hollowed-out(挖空的；掏空的) egg. Chemicals and electricity are then used to encourage the new DNA to fuse with(與合并) the egg and develop into an embryo(胎兒). This technique is called nuclear transfer(核遷移).,Question2: How are clones created?,Qwestion3:Why was Dolly(世界上的第一只克隆羊) impo

9、rtant?,Answer: The sheep was the first mammal(哺乳動(dòng)物) to be cloned using DNA taken from an adult cell. Previously(以前), animals had only been cloned using embryo cells which already have the potential(潛力) to become a complete embryo in its own right(繼承父母的). The big breakthrough with Dolly was to make a

10、 clone from an ordinary, adult cell - in this case from a female goats udder(乳房).,Qwestion4: Are clones normal, healthy animals?,Answer: Dolly is, but scientist do not yet know whether this is the exception(例外) or the rule. Some early evidence suggest that clones may have health problems and that th

11、ey may age prematurely(早衰的，未老先衰).,Question5:Could a human clone be born soon?,Answer: In theory, yes. The techniques used to create Dolly could be applied to(運(yùn)用；適用) humans. But the technology of reproductive cloning is still in its very early stages and there is much that scientists do not understan

12、d. It took more than 200 attempts(努力；試驗(yàn)) to make Dolly. The other embryos failed to implant(播種) in the surrogate(代 理；代替) mother or were miscarried. Even if a clone makes it to birth, at present it has a very low chance of surviving into adult life.,Qwestion6: Has anyone said they will make live huma

13、n clones?,Answer: A number of people have, including Chicago physicist Dr Richard Seed. However, few experts believe that these people have the skills to succeed.,Question7: Are there any benefits from cloning?,Answer: Yes. The techniques used have already demonstrated(展示) benefits. Polly, another s

14、heep clone at the Roslin Institute in Edinburgh has had a human gene(基因) inserted so that it produces a blood clotting(血的)凝結(jié)) agent needed by haemophiliacs(血友癥) in its milk. Cloning of human cells in a laboratory could offer perfectly-matched tissue(（動(dòng)物的）組織) for surgical or genetic repair of humans.

15、,To clone or not to clone,The advantage and disadvantage of clone Advantage: 1)A benefit of cloning is shown through the future of the medical field. It can product organs for disease people. 2)protect endangered animal. 3)it can bring hope for those couples unable to have children. 4)The replacement of dead people ,for example some famous scientist.,Advantage:,disadvantage,1)The threat to genetic diversity and evolution 2)It can rep