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  3. The genetic characteristics of all life forms on earth are embodied in the chemical structure of DNA molecules. An organism’s DN

The genetic characteristics of all life forms on earth are embodied in the chemical structure of DNA molecules. An organism’s DN

admin2010-07-14  68
问题     The genetic characteristics of all life forms on earth are embodied in the chemical structure of DNA molecules. An organism’s DNA molecules provide a complete blueprint for its physical makeup. Genetic engineering is the process of altering the DNA genetic code to change the characteristics of plants and animals. Through the process, scientists can literally build to order new life forms that perform desired functions. For hundreds of years, humans have engineered the development of food crops and domesticated animals through selective breeding practices. For example, the modern dairy cow is the result of centuries of carefully breeding individual animals that carried the genetic trait for high milk production. However, new technology makes it possible for scientists to restructure the DNA molecules themselves and thus obtain more rapid and more radical genetic changes than were possible in the past. This new process is commonly called recombinant DNA technology or gene splicing because it involves disassembling the DNA molecule and then recombining or splicing the pieces according to a new pattern. The gene-spliced DNA molecule may have a genetic code that has never existed before.
    Although recombinant DNA technology is still in its infancy, it has al ready demonstrated its value. New crop breeds produced by this process are already growing in farmers’ fields. Crops that are genetically engineered to resist pests, diseases, and drought could be important in efforts to alleviate starvation around the world. Scientists are trying to use genetic engineering to produce important drugs such as insulin (胰岛素) and interferon (干扰素) cheaply. They are also working on a genetically engineered generation of wonder drugs to combat cancer and other killer diseases. However, the recombinant DNA technology brings with it problems our society has not previously faced. Gene splicing could produce new disease microorganisms, deadly to us or to the plants and animals upon which we depend. The possibility of altering human genetic structure raises serious moral, political, and social is sues. Genetic engineering illustrates dramatically the promises and dangers of technological development. The decisions our society makes about genetic engineering will undoubtedly have tremendous consequences in the years to come.
Which of the following is NOT mentioned about recombinant DNA technology?
选项 A、It can bring about rapid and radical genetic changes in life forms.
B、It can be used to restructure DNA molecules to produce new desired plant and animal breeds.
C、It may increase the risk of producing some unexpected diseases.
D、It proves an effective way to cure cancer and other incurable diseases.
答案D
解析
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