新视野英语完整教材3-8

1、Preview The Theory of Relativity, the splitting of the atom, the first space flight and then there was Dolly! The world of human cloning is suddenly within reach. What was science fiction yesterday is reality today. However, cloning has caused panic as well as excitement among both scientists and co

2、mmon people. Some conservative people are afraid that human cloning would threaten human society and dignity. According to Passage C, the goal of scientists was to raise identical sheep that produce medicine for humans. But as we see, it has opened Pandoras box and no one knows what will happen in t

3、he future. Will people use cloning to breed individuals with genetic qualities seen as desirable? How far will cloning go?Legal and Moral Implications of Cloning At first it was just plain surprising. Word last week that a scientist named Ian Wilmut had succeeded in cloning an adult mammal an achiev

4、ement long thought impossible caught the imagination of everyone. The laboratory process that produced Dolly, an unremarkable-looking sheep, theoretically would work for humans as well. A world with human clones was suddenly within reach. It was science fiction coming to life. In the wake of Wilmuts

5、 announcement, governments hurried to draft guidelines for the unknown, a future filled with incredible possibilities. President Clinton ordered a national commission to study the legal and moral implications of cloning. Leaders in Europe, where most nations already prohibit human cloning, began exa

6、mining the moral implications of cloning other species. Like the Theory of Relativity, the splitting of the atom, and the first space flight, Dollys appearance has generated a long list of difficult puzzles for scientists, politicians, and philosophers. And wild questions on the topic of cloning con

7、tinue to mount. Why would anyone want to clone a human being in the first place? The human cloning situations that experts consider most frequently fall into two broad categories: 1) parents who want to clone a child, either to provide transplants for a dying child or to replace that child, and 2) a

8、dults who for a variety of reasons might want to clone themselves. Will it be possible to clone the dead? Perhaps, if the body is fresh, says one expert. The cloning method used by Wilmuts lab requires combining an egg cell with the nucleus of a cell containing the DNA of the person to be cloned. (D

9、NA is a very long, ribbon -like molecule that contains our genetic information.) And that means that the nucleus must be intact. Cells die and the cell nucleus begins to break apart after death. But, yes, in theory at least it might be possible. Would a cloned human be identical to the original? Ide

10、ntical genes dont produce identical people, as anyone who knows a set of identical twins can tell you. In fact, twins are more alike than clones would be, since they have at least shared the same environment within the mother, are usually raised in the same family, and so forth. Parents could clone

11、a second child who resembled their first in appearance, but all the evidence suggests the two would have very different personalities. Twins separated at birth do sometimes share personality characteristics, but such characteristics in a cloned son or daughter would only be reminders of the child wh

12、o was lost. Even in terms of biology, a clone would not be identical to the master copy. The clones cells, for example, would have energy-processing machinery that came from the egg, not from the person who was cloned. But most of the physical differences between originals and copies are so minor th

13、at detection of them would require a sophisticated laboratory. The one possible exception is bearing children. Wilmut and his coworkers are not sure that Dolly will be able to have lambs. They will try to find out once shes old enough to breed. What if parents decided to clone a child in order to ha

14、rvest organs? Most experts agree that it would be psychologically harmful if a child sensed he had been brought into the world simply as an organ donor. But some parents already produce second children with nonfatal transplants in mind, and many experts do not oppose this. Cloning would increase the

15、 chances for a tissue match from 25 percent to nearly 100 percent. If cloned animals could be used as organ donors, we wouldnt have to worry about cloning twins for transplants. Pigs, for example, have organs similar in size to humans. But the human body attacks and destroys tissue from other specie

16、s. To get around that, one company is trying to alter the pigs genetic code to prevent pig organs from being attacked. If the companys technicians succeed, it may be more efficient to produce such pigs by cloning than by current methods. How would a human clone refer to the donor of its DNA? Mom is

17、not right, because the woman or women who supplied the egg and gave birth to the infant would more appropriately be called Mother. Dad isnt right, either. A traditional father supplies only half the DNA in a child. Judith Martin, in her writings under the name of Miss Manners;, suggests the phrase,

18、Most honored sir or madam. Why? One should always respect ones ancestors, she says, regardless of what they did to bring one into the world. That still leaves some confusion over vocabulary. The editorial director of one dictionary says that the noun clonee may sound like a good term, but its not clear enough. Instead, he prefers original and copy. What are the other implications of cloning for society? The gravest concern isnt