職稱英語衛(wèi)生A考試試題

1、職稱英語衛(wèi)生 A 考試試題為大家整理了 2013 年職稱英語衛(wèi)生 A 考試試題 ,僅供參考！ 第四十五篇 DNA Fingerprinting 【DNA 指紋】DNA is the genetic material found withinthe 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.

2、, the complete DNA of each individual is unique.DNAfingerprintingissometimes calledDNAtyping.Itisamethodofidentification 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 segment

3、ed using enzymes, and the segments are arranged by size. The segments are marked with probes and exposed on X-rayfilm,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

4、fingerprintingwas firstdeveloped as an identificationtechnique 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 crim

5、inalinvestigations, 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 numb

6、er 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 fingerprint may not be unique; large-scal

7、e research to confirm the uniqueness of DNA fingerprinting test results has not been conducted. In addition, DNA fingerprinting isoften 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

8、 lead to false results.DNA fingerprintingis 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 ofDNAtesting foridentificationpurposes may lead to the establishment of a DNA fing

9、erprint database.1. According to the essay, we can find chromosomesA. in a fish.B. in a tree.C. in a sheep.D. in a rock.2. DNA fingerprinting is more often used forA. obtaining samples of chromosomes.B. providing evidence in court investigations.C. proving the horse to be a mammal.D. printing books

10、about biology.3. When your brother looks exactly like you, your complete DNA may beA. exactly like his.B. totally different from his.C. unique.D. lost.4. Some people believe that using a DNAfingerprintmay not be so reliable becauseA. the accuracy of DNA fingerprinting has been challenged.B. no priva

11、te 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 fingerprintingconcerning the followingaspects

12、 EXCEPTA. 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指紋DNA是所有生物細(xì)胞核子發(fā)現(xiàn)的基因材料。哺乳動(dòng)物的DNA線被組合為稱作染色體的各種結(jié)構(gòu)。除生物姊妹體外 (如完全相同的雙胞胎 )，每一個(gè)體的整條DNA 是獨(dú)一無二的。DNA 指紋有時(shí)也稱作 DNA 印記法。這是一種通

13、過比較少量 DNA 的鑒別方法。DNA 指紋的構(gòu)成先要從身體組織或液體中抽取 DNA 標(biāo)本，如頭發(fā)、血液或唾液。采取的標(biāo)本用酶分割成若干部分，各切片根據(jù)大小排列。切片先用探針做標(biāo)記，然后曝光于 X 光片上。膠片上形成由黑色條紋組成的圖案，這就是 DNA 指紋。若兩個(gè)不同標(biāo)本的 DNA 指紋完全相像，則這兩個(gè)標(biāo)本可能來自同一人。DNA1985 年。開始是用來探測(cè)遺傳疾指紋首次作為鑒別技術(shù)進(jìn)行開發(fā)是在病的，很快便被應(yīng)用于刑事調(diào)查與法律事務(wù)?；贒NA 所提供證據(jù)的首例定罪是 1988 年，在美國(guó)。在刑事調(diào)查中，把從犯罪現(xiàn)場(chǎng)采集的證據(jù)中提取的DNA 村本與犯罪嫌疑人的相比。一般說來，法庭已承認(rèn)DNA 測(cè)試的可靠性并允許 DNA 測(cè)試結(jié)果納為證據(jù)然而，在一些方面DNA 指紋頗具爭(zhēng)議性：結(jié)果的精確性，測(cè)試成本及技術(shù)的錯(cuò)誤使用的可能性。由于一些原因， DNA 指紋的精確性受到了挑戰(zhàn)。首先，由于是 DNA 切片而并非完整的 DNA 被作為指紋進(jìn)行研究 ;DNA 指紋可能并非獨(dú)一無二的 ;尚未進(jìn)行過大規(guī)模研究以證實(shí) DNA 指紋測(cè)試結(jié)果是獨(dú)一無二的。此外， DNA 指紋常是在私人實(shí)