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| 文章出处：学生大考试站 发布时间：2005-11-17 |
第三部分 阅读理解 (80分)
Passage 1
In recent years, scientific and technological developments have drastically changed human life on our planet, as well as our views both of ourselves as individuals in society and of the universe as a whole. Maybe one of the most profound developments of the last decade is the discovery of recombinant DNA technology, which allows scientists to introduce genetic (遗传学的) material (or genes) from one organism into another. In its simplest form, the technology requires the isolation of a piece of DNA, either directly from the DNA of the organism under study, or artificially synthesized from an DNA. This piece of DNA is then ligated (结扎) to a fragment of bacterial DNA which has the capacity to replicate (复制) itself independently. The recombinant molecule thus produced can be introduced into the common intestinal (内部的) bacterium Escherishchia coli, which can be grown in very large amounts in synthetic media. Under proper conditions, the foreign gene will not only replicate in the bacteria, but also express itself, through the process of transcription and translation, to give rise to large amounts of the specific protein coded by the foreign gene.
The technology has already been successfully applied to the production of several therapeutically (疗法的) important biomolecules, such as, growth hormones, interferon, insulin.
Many other important applications are under detailed investigation in laboratories throughout the world.
21. Recombinant DNA technology consists primarily of ____________.
○A. producing several therapeutically important biomolecules
○B. giving rise to large amounts of protein
○C. introducing genetic material from one organism into another
○D. using a viral enzyme called reverse transcriptase
22. Recombinant DNA technology has been used in the production of all of the following biomolecules except ___________.
○A. growth hormones
○B. Escherishchia coli
○C. interferon
○D. insulin
23. Which of the following is not true?
○A. The foreign gene will replicate in the bacteria, but it will not express itself through transcription and translation.
○B. The bacterium Escherishchia coli can be grown in large amounts in synthetic media.
○C. Research continues in an effort to find other uses for this technology.
○D. Recombinant DNA technology is a recent development.
24. Expression of a gene in Escherishchia coli requires ________.
○A. the viral enzyme reverse transcriptase
○B. the processes of transcription and translation
○C. production of insulin and other biomolecules
○D. that the bacteria be grown in a synthetic media
25. The term recombinant is used because ___________.
○A. by ligation, a recombinant molecule is produced, which has the capacity of replication
○B. the technique requires the combination of several types of technology
○C. by ligation, a recombinant protein is produced, part of whose amino acids come from different organism
○D. Escherishchia coli is a recombinant organism
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