常用的DNA聚合酶主要有大肠杆菌DNA聚合酶I1,Taq DNA聚合酶,大肠杆菌DNA聚合酶I1Klenow片段,T4 DNA聚合酶,T7 DNA聚合酶,反转录酶等。

所有的DNA聚合酶都具有

A:3′→5′聚合酶活性 B:5′→3′聚合酶活性 C:5′→3′核酸外切酶活性 D:3′→5′核酸外切酶活性 E:内切酶活性

常用的DNA聚合酶主要有大肠杆菌DNA聚合酶I1,Taq DNA聚合酶,大肠杆菌DNA聚合酶I1Klenow片段,T4 DNA聚合酶,T7 DNA聚合酶,反转录酶等。

能够体外合成cDNA的聚合酶是

A:TaqDNA聚合酶 B:T4 DNA聚合酶 C:反转录酶 D:Klenow酶 E:DNA聚合酶I

限制性核酸内切酶，简称限制酶，是一类能识别双链DNA分子中特定的核苷酸序列，并在识别序列内或附近切割DNA双链结构的核酸酶。

限制性核酸内切酶切割DNA后不会产生

A:黏性末端 B:5′黏性末端 C:3′黏性末端 D:平末端 E:单链缺口

2-乙酰氨基芴(2-AAF)和2-氨基芴(2-AF)在机体内可形N-羟基芳酰胺和N-羟基芳胺，为近致癌物，再通过结合反应而产生的结合物可在酸性pH尿中或由肠道菌丛的β-葡萄糖苷酸酶水解，生成N-羟基芳香胺。可自发生成亲电子剂--氮宾离子，攻击DNA，引起膀胱癌和结肠癌

近致癌物N-羟基芳酰胺和N-羟基芳胺的形成通过

A:细胞色素P450和FMO催化 B:细胞色素P450催化 C:FMO催化 D:环氧水化酶催化 E:醇脱氢酶催化

DNA Fingerprinting

    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.¹ With the exception of identical siblings (as in identical twins)²，the complete DNA of each individual is unique.

    DNA fingerprinting is sometimes called DNA typing.³ It is a method of identification that compares bits of DNA. A DNA 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.⁴ 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 diseases⁵，it soon came to be used in criminal investigations and legal affairs. The first criminal conviction based on DNA evidence⁶ in the United Statesoccurred 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.

词汇：

figerprinting /ˈfɪŋgəprɪnt/ n. 指纹法，指纹术 

nucleus /"nju:klɪəs/ n. 核，中心
genetic / dʒəˈnetɪk / adj. 遗传的 

mammal /ˈmæml/ n. 哺乳动物
chromosome /ˈkrəʊməˌsəʊm/ n. 染色体 

identification /"aɪˌdentɪfɪˈkeɪʃn/ n. 识别，鉴定，证明
enzyme /"enzaɪm/ n. 酶 

suspect /səˈspekt/ n. 嫌疑犯
fingerprint / ˈfɪŋgəprɪnt / n. 指纹 

saliva /səˈlaɪvə/ n. 唾液
segment /ˈsegmənt/ vt.  分割，分裂；切片，不笨
controversial / ˌkɒntrəˈvɜ:ʃl / adj. 有争议的 

uniform /"ju:nɪfɔ:ml/ adj. 一致的，相同的

注释：

1.In mammals the strands of DNA are grouped into structures called chromosomes.哺乳L动物的 DNA线被组合为称作染色体的各种结构。
2.With the exception of identical siblings (as in identical twins)：生物姊妹体除外（如完全相同的双胞胎）
3.DNA fingerprinting is sometimes called DNA typing. DNA 指纹检查法有时也称 DNA 印记法。
4.The segments are marked with probes and exposed on X-ray film, where they form a pattern of black bars - the DNA fingerprint.切片先用探针做标记，然后在X光片上曝光。胶片上形成 由黑色条纹组成的图案，这就是DNA指纹。
5.Originally used to detect the presence of genetic diseases ： (DNA 指纹法）开始是用来探测遗传病的存在
6.The first criminal conviction based on DNA evidence：基于 DNA 提供证据的首例定罪

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 the results of their tests D:suspects may not have enough money to provide their own DNA to law-courts

DNA Fingerprinting

    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.¹ With the exception of identical siblings (as in identical twins)²，the complete DNA of each individual is unique.

    DNA fingerprinting is sometimes called DNA typing.³ It is a method of identification that compares bits of DNA. A DNA 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.⁴ 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 diseases⁵，it soon came to be used in criminal investigations and legal affairs. The first criminal conviction based on DNA evidence⁶ in the United Statesoccurred 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.

词汇：

figerprinting /ˈfɪŋgəprɪnt/ n. 指纹法，指纹术 

nucleus /"nju:klɪəs/ n. 核，中心
genetic / dʒəˈnetɪk / adj. 遗传的 

mammal /ˈmæml/ n. 哺乳动物
chromosome /ˈkrəʊməˌsəʊm/ n. 染色体 

identification /"aɪˌdentɪfɪˈkeɪʃn/ n. 识别，鉴定，证明
enzyme /"enzaɪm/ n. 酶 

suspect /səˈspekt/ n. 嫌疑犯
fingerprint / ˈfɪŋgəprɪnt / n. 指纹 

saliva /səˈlaɪvə/ n. 唾液
segment /ˈsegmənt/ vt.  分割，分裂；切片，不笨
controversial / ˌkɒntrəˈvɜ:ʃl / adj. 有争议的 

uniform /"ju:nɪfɔ:ml/ adj. 一致的，相同的

注释：

1.In mammals the strands of DNA are grouped into structures called chromosomes.哺乳L动物的 DNA线被组合为称作染色体的各种结构。
2.With the exception of identical siblings (as in identical twins)：生物姊妹体除外（如完全相同的双胞胎）
3.DNA fingerprinting is sometimes called DNA typing. DNA 指纹检查法有时也称 DNA 印记法。
4.The segments are marked with probes and exposed on X-ray film, where they form a pattern of black bars - the DNA fingerprint.切片先用探针做标记，然后在X光片上曝光。胶片上形成 由黑色条纹组成的图案，这就是DNA指纹。
5.Originally used to detect the presence of genetic diseases ： (DNA 指纹法）开始是用来探测遗传病的存在
6.The first criminal conviction based on DNA evidence：基于 DNA 提供证据的首例定罪

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

在DNA重组中，催化形成重组DNA分子的酶是

A:拓扑异构酶 B:DNA连接酶 C:解链酶 D:DNA聚合酶 E:反转录酶

在DNA重组中，催化形成重组DNA分子的酶是

A:拓扑异构酶 B:DNA连接酶 C:解链酶 D:DNA聚合酶 E:反转录酶