【2014年职称英语真题：职称英语考试卫生A试题】：

　　无忧考网为大家整理了2013年职称英语真题：职称英语考试卫生A试题,仅供参考!!

　　第四十五篇 DNA Fingerprinting【DNA指纹】

　　DNA is the genetic material found within the cell nuclei of all living things. In mammals the strands of DNA are grouped into structures called chromosomes. With the exception of identical siblings (as in identical twins., the complete DNA of each individual is unique.

　　DNA fingerprinting is sometimes called DNA typing. It is a method of identification that compares bits of DN A. A DAN fingerprint is constructed by first drawing out a DNA sample from body tissue or fluid such as hair, blood, or saliva. The sample is then segmented using enzymes, and the segments are arranged by size. The segments are marked with probes and exposed on X-ray film, where they form a pattern of black bars—the DNA fingerprint. If the DNA fingerprints produced from two different samples match, the two samples probably came from the same person.

　　DNA fingerprinting was first developed as an identification technique in 1985. Originally used to detect the presence of genetic diseases, it soon came to be used in criminal investigations and legal affairs. The first criminal conviction based on DNA evidence in the United States occurred in 1988. In criminal investigations, DNA fingerprints derived from evidence collected at the crime scene are compared to the DNA fingerprints of suspects. Generally, courts have accepted the reliability of DNA testing and admitted DNA test results into evidence. However, DNA fingerprinting is controversial in a number of areas: the accuracy of the results, the cost of testing, and the possible misuse of the technique.

　　The accuracy of DNA fingerprinting has been challenged for several reasons. First, because DNA segments rather than complete DNA strands are “fingerprinted”; a DNA fingerprint may not be unique; large-scale research to confirm the uniqueness of DNA fingerprinting test results has not been conducted. In addition, DNA fingerprinting is often done in private laboratories that may not follow uniform testing standards and quality controls. Also, since human beings must interpret the test, human error could lead to false results.

　　DNA fingerprinting is expensive. Suspects who are unable to provide their own DNA to experts may not be able to successfully defend themselves against charges based on DNA evidence.

　　Widespread use of DNA testing for identification purposes may lead to the establishment of a DNA fingerprint database.

　　1. According to the essay, we can find chromosomes

　　A. in a fish.

　　B. in a tree.

　　C. in a sheep.

　　D. in a rock.

　　2. DNA fingerprinting is more often used for

　　A. obtaining samples of chromosomes.

　　B. providing evidence in court investigations.

　　C. proving the horse to be a mammal.

　　D. printing books about biology.

　　3. When your brother looks exactly like you, your complete DNA may be

　　A. exactly like his.

　　B. totally different from his.

　　C. unique.

　　D. lost.

　　4. Some people believe that using a DNA fingerprint may not be so reliable because

　　A. the accuracy of DNA fingerprinting has been challenged.

　　B. no private laboratory follows uniform testing standards or quality controls.

　　C. mistakes are possible when researchers explain what have come of their tests.

　　D. suspects may not have enough money to provide their own DNA to law-courts.

　　5. This essay talks about DNA fingerprinting concerning the following aspects EXCEPT

　　A. legal application of the method.

　　B. the way to obtain a DNA sample.

　　C. work yet to be done about DNA fingerprinting.

　　D. possible danger in drawing a DNA sample from the human body.

　　DNA指纹

　　DNA是所有生物细胞核子发现的基因材料。哺乳动物的DNA线被组合为称作染色体的各种结构。除生物姊妹体外(如完全相同的双胞胎)，每一个体的整条DNA是独一无二的。

　　DNA指纹有时也称作DNA印记法。这是一种通过比较少量DNA的鉴别方法。DNA指纹的构成先要从身体组织或液体中抽取DNA标本，如头发、血液或唾液。采取的标本用酶分割成若干部分，各切片根据大小排列。切片先用探针做标记，然后曝光于X光片上。胶片上形成由黑色条纹组成的图案，这就是DNA指纹。若两个不同标本的DNA指纹完全相像，则这两个标本可能来自同一人。

　　DNA指纹首次作为鉴别技术进行开发是在1985年。开始是用来探测遗传疾病的，很快便被应用于刑事调查与法律事务。基于DNA所提供证据的首例定罪是1988年，在美国。在刑事调查中，把从犯罪现场采集的证据中提取的DNA村本与犯罪嫌疑人的相比。一般说来，法庭已承认DNA测试的可靠性并允许DNA测试结果纳为证据然而，在一些方面DNA指纹颇具争议性：结果的精确性，测试成本及技术的错误使用的可能性。

　　由于一些原因，DNA指纹的精确性受到了挑战。首先，由于是DNA切片而并非完整的DNA被作为指纹进行研究;DNA指纹可能并非独一无二的;尚未进行过大规模研究以证实DNA指纹测试结果是独一无二的。此外，DNA指纹常是在私人实验室作的，可能并不遵循统一的测试标准与质量控制。再有，既然必须由人来解释测试，人为的错误可能导致错误结果。

　　DNA指纹颇为昂贵。如果犯罪嫌疑人不能将自己的DNA提供给专家，他/她就很可能没有确凿的证据证明自己无罪。为鉴定目的而作的DNA测试的广泛使用可能会导致DNA指纹数据库的建立。

如有相关问题，可拨打免费咨询热线：010-58443520 或

考试培训小助手

本科留学qq:436560382

研究生留学qq:437946603