It’s hair-raising news for criminals on the run.Scientists behind a new study have worked out how to identify individuals only based on the proteins(蛋白质) in a single strand of their hair.
While the police already look at DNA from hair as part of investigations,the technique is far from ideal:DNA is easily degradable,meaning it can only be analysed within a certain time period after the crime.But the new technique could even be used to solve historical or archaeological cases,making it far superior to DNA sequencing in many ways.
DNA degradation depends on several environmental factors includingtemperature,humidity and PH.It is also affected by the activity of bacteria and other microorganisms.In contrast,actual hairs can survive for a long time—sometimes centuries.After bones and teeth,hair is in fact one of the most resistant structures of the human body.
In order to understand how the protein can be used to identify individuals,it is important to understand that proteins are coded by DNA.This means that a certain level of the genetic variation that we see in different people’s DNA passes into their proteins.In fact,genetic information in the DNA is translated into amino-acid chains that make up proteins.
The method not only allows for human identification but it can also reveal how old the sample is and what region it comes from,so that we can distinguish between current and ancient samples.But while the discovery is exciting,the technique is not quite polished enough to be used in the court room.The main task now will be to analyse hair samples from all over the world,which will make it a lot more reliable.
The new discovery will boost the significance of hair as evidence in courts,at a time when some forensic(司法鉴定的) disciplines have been criticised in the US.It will also be of great use in archaeology.
1.What’s the main idea of the passage?
A.DNA evidence is far from ideal.
B.Criminals on the run get hair-raising news.
C.Scientists are planning a test of human hair.
D.Humans can be identified by proteins in hair.
2.Which evidence is more reliable for the police to identify a criminal?
A.Lost teeth. B.The footprint.
C.Personal belongings. D.Damaged DNA.
3.In what way is the new technique superior to DNA test?
A.Serving as evidence in courts. B.Possessing genetic information.
C.Inferring the height of a person. D.Distinguishing the region of a person.
4.Who will welcome the discovery?
A.Criminals. B.Employers. C.Hairdressers. D.Archaeologists.
语篇解读:本文是一篇说明文。尽管大多数犯罪现场都含有人的毛发,但是细胞核DNA往往缺失,阻碍了案件的侦破。为此,法医界也在积极开发DNA分析以外的身份识别技术。美国联邦安全实验室近日提出了一种方法,将毛发中的蛋白标志物与DNA分析相结合,可实现更准确的人类身份识别。
答案及剖析:
1.D 主旨大意题。根据全文可知,研究表明,可以通过对人毛发中的蛋白质的分析来确定一个人的身份。故选 D项。
2.A 细节理解题。根据第三段中After bones and teeth,hair is in fact one of the most resistant structures of the human body.可知,对骨骼和牙齿的分析数据最为可靠。
3.D 细节理解题。根据第五段中The method not only allows for human identification but it can also reveal how old the sample is and what region it comes from,so that we can distinguish between current and ancient samples.可知,这一方法不仅可以显示个人身份,还可以显示标本的来源地。
4.D 细节理解题。根据最后一段中It will also be of great use in archaeology.可知,这一发现在考古学研究方面价值极高。故选D项。
