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  3. 共用题干 第三篇Genetic EngineeringGenetic engineering began when the DNA molecule（分...

共用题干 第三篇Genetic EngineeringGenetic engineering began when the DNA molecule（分...

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问题 共用题干
第三篇

Genetic Engineering

Genetic engineering began when the DNA molecule（分子）,the most basic unit of life, was first
described in 1953 by James Watson and Francis Crick.An understanding of DNA led to the altering of
normal cell reproduction.Experiments with altering human cells began in 1970.In one of the first
experiments,patients were injected with a virus that would produce a life-saving enzyme,but their bodies
would not accept it.In 1980 patients with a rare but fatal blood disease were injected with a purified gene
that was cloned through DNA technology.Another failure.
Genetic engineering got a legal boost（激励）in 1980. The U. S. Supreme Court said that a patent could
be granted on a genetically engineered " oil-eating" bacterium（细菌）.This bacterium would help clean up
oil spills.The ruling encouraged companies to invent new life forms,and three important medical products
were quickly developed.
1.Human interferon（干扰素）一a possible solution to some cancers and viral diseases. A newly engineered
bacterium produced human interferon as a by-product. This new product reduced the cost of interferon.
2. Human growth hormone（荷尔蒙）一for children whose bodies do not grow to normal height. An
expensive growth hormone was previously produced from human cadavers,but by changing the genetic
make-up of the single-cell bacterium E.coli,and affordable growth hormone could be produced.
3. Human insulin (胰岛素）一for the treatment of diabetes. People with diabetes used to rely on a
beef-or-pork-basedproduct until 1982.Now insulin can be manufactured by genetically altered bacteria.
Advances in genetic engineering have continued,though they constantly must be weighed against the
safety of procedures.There is clearly much more to discover.
选项 Genetic engineering may be defined as_________.
A:the altering of normal cell reproduction
B:a branch of applied chemistry
C:a procedure that holds little promise
D:a study on life-saving enzymes
答案A
解析通读文章可知，本文主要介绍了对DNA有所了解之后，人们改变细胞常规的复制过程 产生的影响。B、C、D三项均不能完全概括文章的主旨，故选A。
由文章第一段中“An understanding of DNA led to the altering of normal cell reproduction.”可 知，所谓的基因工程就是依据对DNA的了解，改变正常的细胞复制过程，以产生所需特性的一 种科学，故选A。
由文章第三段第一句“Human interferon一a possible solution to some cancers and viral diseases.”可知，干扰素是治疗一些癌症和病毒性疾病的潜在药方，故选B。
由文章第3一 5段的内容可知，文章中列出的3个基因药物产品既未依照制作过程顺 序，也未依照时间先后顺序，同时也不是采取故事的叙述形式，故选B。
单词weigh的意思为“称……的重量，权衡”，在文章中的意思为“权衡，考虑”，故选C。第5部分：补全短文
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