深圳机场飞机时刻表:克隆的坏处

来源:百度文库 编辑:查人人中国名人网 时间:2024/04/27 17:13:41
我要英文的,救命,越快越好

Today, the topic of cloning generates more argument then it has ever created before. The controversy over cloning is based, in part, on the fact that there are extreme opposing viewpoints on the subject. Also a major factor in the debate over cloning is a fear of new technology. Throughout history, man has always been slow to adapt to a new technology, or a new way of doing things. We go through all the trouble to adapt to one method, why uproot ourselves and change everything just to do it a different way. This attitude has been evident in the recent past, with inventions such as the automobile and the television. Nuclear power is a prime example of an advanced technology essentially abandoned out of fear. There are very few nuclear power plants left in operation, and there are no new plants being built. This is mainly due to fear of an accident, or to the long lasting effects of this technology.

As with everything, including cloning, there is a negative side. With television, the negative is that children often watch it instead of doing homework, subsequently causing lower grades. It is also believed that television violence influences children into more violent tendencies. A negative to automobiles is the massive pollution a large number of them cause. Entire cities have been put on pollution alert due to toxic smog created, in part, by the automobile. Nuclear power?s major downfall is, aside from the immense destruction caused by an accident, the long-lasting effects of the spent nuclear fuel. Sometimes the negatives outweigh the positives, and the technology is rightfully abandoned, but in most cases the technology is abandoned simply out of fear.

Cloning is not just any new technology, cloning gives us the potential to change the very essence of our being; what we are can be decided before we are even born. There are immense positives to cloning; the end of hunger worldwide, the human life-span lengthened by decades, mental and physical illness a distant memory. These potential positives do not come without a price, however. The potential for abuse of any technology exists. For example, someone using cloning technology could clone an army of Adolph Hitlers1. They could be ?bred? to be warriors, animals, ruthless without remorse. According to one reporter, ?Calls to ban human cloning are based on unsubstantiated fears that cloning will be used for evil purposes. Technology is never bad in and of itself; it is the purposes for which it is used that can be malevolent. Though cloning research does present some dangers, it also has many potential benefits and should not be banned simply out of fear of its possible misuse.?2 However dangerous sounding, the Hitler scenario is completely unlikely due to the great difficulty involved with the cloning of an entire living human being. Cloning is such an amazingly powerful tool; we cannot allow it to be banned simply out of fear.

First off, cloning is not just the photocopying of a living breathing human being. It takes a great deal of time and effort to clone a living being. Also, the clone would not have the memories and experiences that the original has. That technology does not yet exist. There are many things that can be cloned; single cells, plants, organs, animals, and eventually entire human beings. The technology to clone a human exists, but we have not moved into that area of cloning yet. This is due, in part, to the fact that people are afraid of a new technology, and partially to the fact that some people believe cloning violates their morals. Just as with anything new, we start with small steps, and move into bigger ones. In cloning, we started with simple genetic alterations. Not necessarily with humans, but with plants and animals. For example, a team of researchers has successfully altered the genes of a cherry tomato so it will grow entirely in salt water. If these genetic alterations could be applied to corn, rice, or other high-yield foods, hunger would vanish from the face of the earth3. Margret Hyde, speaking on the subject ??The use of gene-splicing may help to increase the food supply.?4 Thousands of people die from hunger every day, most of them in poor, underdeveloped countries and China. If the USA were to develop this technology to a level where it practical in everyday life, the majority of these people would live. There is no need for children to die a slow, horrible death of hunger and malnutrition. If only we were not afraid to embrace this new technology.

Another extremely useful application of the cloning technology would be the cloning of organs or tissues for the body. With this, we could not only cure our suffering and dying, we could prolong our life-span by decades. It wouldn?t be uncommon for people to live to one hundred and fifty years old, or older. If a kidney fails in old age, take the few good cells left and clone a brand new kidney. If someone suffers a massive heart attack, clone a new heart. After more development of cloning, there is even the possibility to repair brain and spinal column damage. Christopher Reeves could walk again5. These life-prolonging procedures wouldn?t be reserved for the rich and famous, they could be used on everyone. Take, for example, a man who has drank all of his life. He is now in his 40?s and has severe liver cirrhosis. Without a liver transplant, he will die. And even if he gets a liver transplant, there is no guarantee that it will save him; it could reject. If the man gets a liver, and if it doesn?t reject, he then has to live out the remainder of his life on rejection medicine, and even a simple cold could kill him. Now if cloning was a common practice, the doctors would simply take a few healthy liver cells and clone a brand-new liver for the man. Since the liver is a clone of the original, the liver cells have exactly the same DNA and there is no chance for rejection. So he is guaranteed a liver that will not reject, and he won?t have to spend his life on rejection drugs.

Now there is the subject of cloning an entire human being. It is this side of cloning that generates the most controversy of all. People believe that it is not ethical to clone a human being. These beliefs are based on the premise that God created humans in His image, and their soul is given to them by God. Therefore, it is not our place to create a human being; it is God?s. In their view, we would be playing God, and this should not happen. But science does not recognize that a god created the universe, science believes that the universe created itself out of a ?big bang?. From this point of view, God did not create man, and there is no moral boundary to cloning a human being.

The methods that scientists use to clone a human being are essentially simple.

To clone, Wilmut used methods his research group and others had been developing for more than a decade. His colleague Keith Campbell sucked the nucleus out of an egg that had been removed from a ewe, creating a cell that had no genes at all, an egg that would soon die if it did not get a new nucleus. Then he began the process of adding the nucleus of an udder cell to the bereft egg. Campbell slipped the udder cell under the outer membrane of the egg. Next, he jolted the egg for a few microseconds with a burst of electricity. This opened the pores of the egg and the udder cell so that the contents of the udder cell, including the chromosomes, oozed into the egg and took up residence there. Now the egg had a nucleus - the nucleus of the udder cell. In addition, the electric current tricked the egg into behaving as if it were newly fertilized, jump-starting it into action. After 277attempts to clone an udder cell, Wilmut's group succeeded and Dolly was created. 6

To clone a human being, the process would be the same. The cell does not necessarily have to be a breast cell, it could be any cell in the body; since all cells contain the complete set of DNA for a human being. However, it is wise to use the most unspecialized cell possible, since it has the potential to become any cell. These master cells or "stem cells", as they are often called, are the cells we start out as. They divide and re-divide until they form specialized cells such as heart, liver, lung, and brain cells. If we could clone these stem cells, we could regenerate brain or spinal column tissue. It would be as common to get a spinal cord transplant as it would to get a kidney or liver transplant today. Also, these people would not have to live on rejection medicine all of their lives, worrying about getting even the littlest infection or disease.

Cloning is fairly good,but it's not good for people.If we clone,the world will be lots of people,will be very crowded,if we clone too much,
the end of world is not so far.