大学英语-习题及答案-大学英语Ⅲ-Unit8 Supplementary Reading and Exercises

Unit Eight Supplementary Reading and ExercisesAbout CloningHistory of CloningIn 1962, biologist John Gurdon of Oxford University announced that he had used the nucleus of fully differentiated adult intestinal cells to clone South African frogs. Gurdon's results electrified the scientific community, but some scientists remained skeptical and began to find flaws in his work.In 1963, the British biologist J.B.S. Haldane is credited to have coined the term "clone" in a speech entitled "Biological Possibilities for the Human Species of the Next Ten-Thousand Years." Even though many scientists had described, and even completed the cloning process by this time, the term "cloning" had never been used to describe such experiments.In 1966, Marshall Niremberg, Heinrich Mathaei, and Severo Ochoa crack the genetic code. The cracking of the genetic code opened the door for the explosion of genetic engineering studies and achievements beginning in the late 1970's.In 1967, the enzyme DNA ligase was isolated. DNA ligase binds together strands of DNA. Its discovery, with the isolation of the first restriction enzyme 1970, paved the way for the first recombinant DNA molecules to be created by Paul Berg in 1972. In the recombinant DNA process, ligase bonds the "sticky" ends of complimentary DNA strands previously cut by a restriction enzyme.In 1969, James Shapiero of Harvard University, working with Johnathan Beckwith announce that they had isolated the first gene. The gene directed the digestion of sugar in a certain type of bacteria. Shapiero and Beckwith's discovery part of a wave of molecular biology discoveries directly following the 1966 cracking of the genetic code. The announcement also increased the public's concern about the growing power of molecular biologists.In 1970, both Howard T emin and David Baltimore, working independently, isolated the first restriction enzyme. The restriction enzyme, called Reverse Transcriptase, cut DNA molecules at precise locations. This capability led to the future manipulation of DNA.In 1972, Paul Berg of Stanford University created the first recombinant DNA molecules by combining the DNA of two different organisms.In 1973, Stanley Cohen and Herbert Boyer created the first recombinant DNA organism using recombinant DNA techniques pioneered a year earlier by Paul Berg. Recombinant DNA, also called gene splicing, is a technique that allows scientists to manipulate the DNA of an organism.In 1977, German developmental biologist Karl Illmensee, working with Peter Hoppe at Jackson Laboratory in Maine, created mice with only a single parent. They grew mice with only a father as well as mice with only a mother.In 1979, One of the most surprising of modern genetics announcements was made, Karl Illmensee claimed to have cloned three mice in 1979. The announcement came at a time where a succession of failed cloning attempts were beginning to convince biologists that the cloning of a mammal was impossible.In 1983, In what has been called by some the greatest achievement of modern molecular biology, Kary B. Mullis developed the polymerase chain reaction (PCR) in 1983. PCR allows the rapid synthesis of designated fragments of DNA. Using the technique, over one billion copies can be synthesized in a matter of hours.In 1983 Davor Solter, working with David McGrath, attempted to clone mice using his own version of the nuclear transfer method. They wanted to use the cloning experiment to determine if DNA specializes as a cell specializes.In 1984, Danish scientist Steen Willadsen succeeded in cloning a sheep from embryo cells. His work was the first verified cloning of a mammal using the method of nuclear transfer.In 1985 Steen Willadsen, the first to clone a farm animal using the nuclear transfer method, joined Grenada Genetics, a bioengineering company. Willadsen used his cloning technique to duplicate the embryos of prize cattle. Grenada Genetics saw the profitability of the future cattle cloning industry. Top breed cattle embryos were highly desired by farmers, Willadsen's procedure mass produced identical copies of such embryos.In 1986, while working at Grenada Genetics, Steen Willadsen cloned a cow using differentiated, one week old embryo cells. The work proved that the genetic information of a cell did not diminish as a cell specialized and that DNA could return to its original state. Willadsen never officially published hisresults, but the work was a strong influence in Ian Wilmut's decision to attempt to clone from adult cells, which he accomplished in the famous 1996 birth of "Dolly."In 1986, Neal First, Randal Prather, and Willard Eyestone, working at the University of Wisconsin, cloned a cow from early embryo cells. Though the race to clone the first farm animal had already been won by Steen Willadsen in 1984, Prather, Eyestone, and First's project was undertaken roughly at the same time as Willadsen's.In October of 1990, the National Institutes of Health officially began the Human Genome Project, a massive international collaborative effort to locate the 50,000 to 100,000 genes and sequence the estimated 3 billion nucleotides making up the entire human genome. By determining the complete genetic sequence, scientists hope to begin correlating human traits with certain genes. With this information, medical researchers have begun to determine the intricacies of human gene function, including the source of genetic disorders and diseases that have plagued medical researchers for years.In July 1995, Ian Wilmut and Keith Campbell of the Roslin Institute in Scotland successfully cloned two sheep, named Megan and Morag, from differentiated embryo cells. The idea to clone sheep was arrived at by Ian Wilmut as an answer to a gene insertion project he was researching. At the time, time inserting genes into embryo cells was a difficult and tedious process. Few embryos survived the insertion of a gene, even fewer incorporated the gene into their genetic code, and even fewer organisms developed properly and used the gene in all of their cells.On July 5, 1996, Dolly, the first organism ever to be cloned from adult cells, was born. Ian Wilmut and Keith Campbell, researchers at the Roslin Institute in Scotland created Dolly using a technique similar to that with which they created the first sheep from differentiated embryo cells in 1995.On March 4, 1997, President Clinton, in response to the large scale human cloning ethics debate brought about by Ian Wilmut's announcement of the creation of Dolly, proposed a five year moratorium on federal and privately funded human cloning research. In addition to this proposal, Clinton asked the National Bioethics Advisory Commission to review the prospects of human cloning and determine if legal preventive actions should be taken.On December 5, 1997, Harvard graduate Richard Seed announced that he planned to clone a human being before any federal laws could be enacted to ban the process. Seed's announcement added fuel to the raging ethical debate on human cloning that had been sparked by Ian Wilmut's creation of Dolly, the first clone obtained from adult cells.In July 1997, building upon their success of the creation of Dolly, the first animal cloned from adult cells, Ian Wilmut and Keith Campbell created Polly, a Poll Dorset lamb cloned from skin cells grown in a lab and genetically altered to contain a human gene. Polly's birth signified the first step in the application of cloning technology to the production of a useful product. Most scientists believe that most beneficial application of cloning will come from the exact reproduction of animals genetically altered to produce human proteins or organs more easily accepted in transplants. Wilmut and Campbell's creation of Polly surprised the scientific community by how fast cloning technology was progressing. The cloning of genetically altered farm animals was not expected for another five years.In July 1998, Ryuzo Yanagimachi, Toni Perry, and T eruhiko Wakayama of the University of Hawaii announced that they had cloned fifty mice from adult cells since October of 1997. The new cloning technique, which has proven to be more efficient than that performed by Ian Wilmut in his cloning of Dolly, was developed by postdoctoral student Wakayama in his spare time.Future of CloningHuman cloning technology could be used to reverse heart attacks. Scientists believe that they may be able to treat heart attack victims by cloning their healthy heart cells and injecting them into the areas of the heart that have been damaged.There has been a breakthrough with human stem cells. Embryonic stem cells can be grown to produce organs or tissues to repair or replace damaged ones. Skin for burn victims, brain cells for the brain damaged, spinal cord cells for quadriplegics and paraplegics, hearts, lungs, livers, and kidneys could be produced. By combining this technology with human cloning technology it may be possible to produce needed tissue for suffering people that will be free of rejection by their immune systems. Conditions such as Alzheimer's disease, Parkinson's disease, diabetes, heart failure, degenerative joint disease, and other problems may be made curable if human cloning and its technology are notbanned.·Infertility - With cloning, infertile couples could have children. Despite getting a fair amount of publicity in the news current treatments for infertility, in terms of percentages, are not very successful. Couples go through physically and emotionally painful procedures for a small change of having children. Many couples run out of time and money without successfully having children. Human cloning could make it possible for many more infertile couples to have children than ever before possible.· Kidney failure - we may be able to clone kidneys for kidney transplants· Leukemia - we should be able to clone the bone marrow for children and adults suffering from leukemia. This is expected to be one of the first benefits to come from cloning technology.· Cancer - we may learn how to switch cells on and off through cloning and thus be able to cure cancer· Cystic fibrosis - we may be able to produce effective genetic therapy against cystic fibrosis. Ian Wilmut and colleagues are already working on this problem.· Spinal cord injury - we may learn to grow nerves or the spinal cord back again when they are injured. Quadriplegics might be able to get out of their wheelchairs and walk again.· Testing for genetic disease - cloning technology can be used to test for and perhaps cure genetic diseasesThe above list only scratches the surface of what human cloning technology can do for mankind. The suffering that can be relieved is staggering. This new technology heralds a new era of unparalleled advancement in medicine if people will release their fears and let the benefits begin.Is Cloning Wrong or Right?Can we and should we clone humans?WrongThe biggest problem with the use of cloning on a large is scale is the decline in genetic diversity. Think about it, if everyone has the same genetic material, what happens if we lose the ability to clone. We would have to resort to natural reproduction, causing us to inbreed, which will cause many problems. Also, if a population of organisms has the same genetic information, then the disease wouldwipe out the entire population. Helping endangered species by cloning will not help the problem. Currently, zoologists and environmentalists trying to save endangered species are not so much having trouble keeping population numbers up, but not having any animals to breed that are not cousins. The technique of nuclear transfer is also early in its developmental stages. Thus, errors are occurring when scientists carry out the procedure. For instance, it took 277 tries to produce Dolly, and Roslin scientists produced many lambs with abnormalities. If we tried to clone endangered species we could possibly kill the last females integral to the survival of a species. This may be the main reason science is holding out on cloning humans.RightThe goals and purposes for cloning range from making copies of those that have deceased to better engineering the offspring in humans and animals. Cloning could also directly offer a means of curing diseases or a technique that could extend means to acquiring new data for the sciences of embryology and how organisms develop as a whole over time. Currently, the agricultural industry demands nuclear transfer to produce better livestock. Cloning could massively improve the agricultural industry as the technique of nuclear transfer improves. Currently, change in the phenotype of livestock is accomplished by bombarding embryos of livestock with genes that produce livestock with preferred traits. However, this technique is not efficient as only 5 percent of the offspring express the traits. Scientists can easily genetically alter adult cells. Thus, cloning from an adult cell would make it easier to alter the genetic material. The goal of transgenic livestock is to produce livestock with ideal characteristics for the agricultural industry and to be able to manufacture biological products such as proteins for humans. Farmers are attempting to produce transgenic livestock already, but not efficiently, due to the minimal ability to alter embryos genetically, as stated above. Researchers can harvest and grow adult cells in large amounts compared to embryos. Scientists can then genetically alter these cells and find which ones did transform and then clone only those cells.Can we and should we clone humans?Cloning humans has recently become a possibility that seems much more feasible in today's society than it was twenty years ago. It is a method that involves the production of a group of identicalcells or organisms that all derive from a single individual. It is not known when or how cloning humans really became a possibility, but it is known that there are two possible ways that we can clone humans. The first way involves splitting an embryo into several halves and creating many new individuals from that embryo. The second method of cloning a human involves taking cells from an already existing human being and cloning them, in turn creating other individuals that are identical to that particular person. With these two methods almost at our fingertips, we must ask ourselves two very important questions: Can we do this, and should we? There is no doubt that many problems involving the technological and ethical sides of this issue will arise and will be virtually impossible to avoid, but the overall idea of cloning humans is one that we should accept as a possible reality for the future.Embryonic cloning could be a valuable tool for the studying of human development, genetically modifying embryos, and investigating new transplant technologies. Using cloning to produce offspring for the sake of their organs is an issue that we must also face and question whether or not it is morally right. No one will say that it is okay to kill a human being for the sake of their organs, but many have no objection to cloning thousands of individuals that look alike. Technology seems to take away many of the morals that we have worked so hard to install in society. Most people only seem to want to cater to their own needs and do not bother to consider the consequences that society and the clone may have to face.Reading Comprehension:The Transplant List Grows LongerAccording to the United Network of Organ Sharing (UNOS), which works with the U. S. Department of Health and Human Services, more than 75 000 patients are waiting for a transplant. Everyday, some 15 of them will die because an organ isn't available."The magnitude of the organ shortage is sobering. Of' those 75 000 people, probably less than a third will get the. transplant they need this year. And each year, that gap widens, " says UNOS president Patricia Adams, MD2.Yet seemingly, this is an avoidable tragedy. People die everyday. Why can't their organs be harvested to treat those who have no other alternative?The answers are complex, and, experts say, have as much to do with superstition as science. For instance, organ donation doesn't disfigure the body and won't interfere with your funeral, although many fear that.In addition, organs aren't as abundant as one might think. Most people are either too sick or old when they die to be viable donors. The "ideal" candidate is a young person I who is brain dead, in other words, the victim of a traumatic injury. But there are fewer of those thanks to seat belts or I motorcycle helmet laws."The solution is clearly to try to increase the number of. people who donate since we already know on the donation side … only about half the people who are in a position to donate choose to do so when asked, " Jon Nelson, director of, the Office of Special Programs at the U. S. Health Resources and Services Administration, said. Nelson's agency oversees federal transplant program, which consists of dozens of local procurement organizations.Part of the problem, Nelson says, is that getting people to commit to donation is a delicate matter. U if he or she is deceased, may not have a thing to say about it. That means the person trying to procure the organ generally must work with the grieving family, a situation requiring great tact and patience."It's very much an artful thing. It's a sensitivity that an individual might have that predisposes them to be successful in convincing the family, " Nelson says. Ironically, medical science itself has become a problem in that doctors are increasingly efficient at making transplants work and coming up with new uses for them, but the pool of donors really hasn't changed much in the last decade. According to UNOS, the number on the waiting list in 1990 was around 20 000, but itgrew to 73 000 by the year 2000.One relatively new way around the shortage is state registries, which contain information about a donor's wishes and would, in theory, reduce the need to depend on the family or a driver's license, which might get separated from the body. Some 16 states have these programs, including Louisiana and Illinois.Still, even though up to 90% people think organ donation is a good thing, only about half consent.In Europe, Nelson says, the law favors presumed con-sent within limits. In the U. S., the family's wishes almost always prevail.Until more donors step forward, the U. S. is stuck with a controversial allocation system developed by the former Clinton administration and put into place last year. It favors the sickest patients in the region, instead of providing an available organ to the nearest transplant center. That angered many who had worked hard to support their local programs."So the fear was the all the good work that you were doing yields nothing to your local community, " Nelson says.Meanwhile, new Health and Human Services Secretary Tommy Thompson says the new emphasis has to be on organ donation."American generosity is unparalleled, " Thompson says. "Let's use that generosity to increase organ donation and make miracles happen through transplantation. "Plenty of miracles are needed. According to UNOS,there's a shortage of nearly 50 000 kidneys alone. About 17 000 livers are needed.While it's against the law to buy or sell organs, some efforts are being made to help live organ donors defray some of their expenses. Earlier this month, a bill passed the House that would cover travel and subsistence costs. The legislation, now in the Senate, would provide $5 million annually to States and organ banks who need to bring in donors.Is this an ethical problem? "I'm not for buying organs. I'm not for payment, but I am for handling reasonable costs and making it convenient when you have to do this, says Arthur Caplan, PhD. director of the Center for Bioethics at the University of Pennsylvania in Philadelphia. "I think everybody understands that there's no incentive to make your kidney available just because someone's going to give you a free ride to the hospital, " Caplan says.Various schemes have been proposed to increase organ supply, including covering funeral expenses for donors, or setting up an insurance fund for the family, or perhaps even some kind of a scholarship."Everybody's tried in many ways to game the situation and come up with something that'spalatable and ethical and legal, but thus far*, it's always come back to the fact that buying and selling of organs is illegal, " says Edward Nelson, MD, a transplant surgeon at the University of Utah in Salt Lake City.What about the possibility of getting a prisoner to donate an organ in return for an earlier parole?"The main reason that's a terrible idea-" is prisoners have the highest rates of infectious disease of anybody, " Caplan says.There are new technologies to "grow" organs for transplant —literally — from the ground up by using primitive "stem cells" as building blocks. So-called "xenotransplants" would genetically modify organs from pigs and adapt them to humans."These high-tech…so lutions to the organ shortage, I would love to see one make a significant impact, but I don't think it's practical for us to depend on that," says Nelson..Reading comprehension.1) These who are willing to donate organs are about______ of those who can donate.A. 1/3B. 50%C. 90%D. 16%2) The shortage of organs is not because ______ .A. many Americans are superstitiousB. most people are either too sick or old when they die to be viable donorsC. many families of the dead the U. S. fear that donation I will misshape the bodyD. medical science itself has become a problem3) Which of the following is not true to the passage ?A. State registries would help organ transplantation by providing information about a donor's.B. Families wishes are dominant in deciding whether donate or not in the U. S. .C. The author is not pleased with Clinton's allocation system.D. Some efforts are being made to legalize buying and selling of organs.4) It is inferred but not stated in this passage that ______ .A. some people suggested getting prisoners to donate organsB. up to 90% Americans are pleased at organ donationC. the power of legislation is now held by the SenateD. people can change the genes of pigs' organs and then transplant them to human bodies5) "...and making it convenient when you have to do this” “this” refers to _____.A. buying organsB. paymentC. handling reasonable costsD. handling reasonable costs and making it convenientTranslationAs we approach 21st century it is clearer than ever that science and technology are changing the way we live and work. The breakthroughs in bioengineering science are helping to unravel the mysteries of life. Holding out new hope for lifesaving cures to some of our most dreaded diseases.In 1997, the great news shocked the whole world that the British scientists created a lamb named Dolly from a single cell. Miraculously, the cell had been taken from the udder of an adult sheep, which marks the first time an adult animal had been successfully cloned.But it soon caused worldwide concern over its ethical social, and scientific implications. Cloning is especially controversial because it raises the prospect of "making " humans genetically identical to an existing man or woman. Some people claim attempting to use these cloning techniques to actually clone a human being is untested and unsafe and morally unacceptable.How to look upon this new technique? When it comes to a discovery like cloning, we must move with caution, care and deep concern about the impact of our actions. First, cloning should be greatly esteemed and great thanks should be given to its inventors. Meantime, great efforts should be made to place this technique under strict control. Especially we should adopt a document against human cloning since past experience tells us a new invention may cause troubles if it is misused.Short Answer QuestionsReading the passage carefully. Then answer the questions or complete the statements in fewest possible words (not exceeding 10 words).Americans are proud of their variety and individuality, yet they love and respect few things morethan a uniform, whether it is the uniform of an elevator operator or the uniform of a five-star general.Why are uniforms so popular in the United States'? Uniforms have advantages in that they look professional and offer practical benefits, but they also have disadvantages in that they lack variety or individuality as well as posing some practical problems.Among the arguments for uniforms, one of the first is that in the eyes of most people they look more professional than civilian clothes. People have become conditioned to expect superior quality from a man who wears a uniform. The television repairman who wears a uniform tends to inspire more trust than one who appears in civilian attire. Faith in the skill of a garage mechanic is enhanced by a uniform. What easier way is there for a nurse, a policeman, a barber, or a waiter to lose professional identity than to step out of uniform?Uniforms also have many practical benefits. They save on other clothes. They saveon laundry bills. They are tax-deductible . They are of ten more comfortable and more durable than civilian clothes. They also save the tine and effort that would otherwise be spent in shopping for civilian clothes and in deciding what to wear.Primary among the arguments against uniforms is their lack of variety and the consequent loss of individuality experienced by people who must wear them. Though there are many types of uniforms, the wearer of any particular type is generally stuck with it, without change, until doomsday or retirement. When people look alike, they tend to think, speak, and act similarly, on the job at least. They often become carbon copies of one another. Thus, a person in uniform can suffer monotony and lose his individuality.Uniforms also pose some practical problems. Though they are long-lasting, often their initial expense is greater than the cost of civilian clothes. Some uniforms are also expensive to maintain, requiring professional dry cleaning rather than the home laundering possible with many types of civilian clothes. They are often inconvenient as well, particularly to the more youthful wearer who desires to hurry away from work for a date but must first make some type of bothersome arrangement to change into civilian clothes.Uniforms are popular in the United States, but Americans lose as well as gain fromthem. Uniforms have logical as well as psychological advantages and disadvantages. It is questionable whether or not the rewards are worth the price that is paid for them.1. We can learn from the third paragraph that people expect to receive _____from those who wear uniforms.2. Americans' love and respect for uniforms do not seem to be in line with their _____.3. The wearers of a particular type of uniform tend to behave in a _____ way and consequently lose their individuality.4. Uniforms often cause _____ to those who are anxious to go for a date right after work.5. Though uniforms are popular in the United States, they are not _____ clothes in life.。