The magic of DNA technology

Old saying, "Long Long-sheng, Feng Feng-sheng, the son of a rat holes will be." All the biological characteristics of DNA molecular structure by the decision. Biological differences between species, due to the genome sequence differences in rank due to differences in species, is due to the genome structure of the gene expression differences. In short, is the number of nucleotide differences in the number of permutation and combination and resulted in different species. Now shows that only 0.1 percent among people% of the genetic differences between chimpanzees and human genes, only 1%% of the difference. The use of the characteristics of the fight against crime, mainly: on-site analysis can be extracted from animals, plants and micro-organisms as well as the DNA, to determine the scope of the investigation, that tracking suspects.

1985 British biologist at the University of Leicester in the study, Professor Li克杰弗里斯gene variant gene was found on some small structures, which are sufficient to distinguish between the different structure of the individual. As a result, he thought of the possibility of the use of the structural differences to distinguish between different people, and to draw the world's first piece of DNA fingerprinting. The DNA identification, the police around the world attach great importance to its traditional biological forensic examination can only rule out suspects, not identified a suspect technology to a new stage. At present, the technology has been most countries in the world available.

For more than 20 years, DNA identification techniques have been establishing a DNA fingerprint, PCR amplification and RFLP analysis of mitochondrial DNA sequencing and other major technology. These new technologies and new ways to test genetic markers of increasing the information provided by the ever-increasing, so that the test toward fast, sensitive, accurate and trace, automation and quality requirements of the samples are becoming less and less development, more Good to meet the various needs of the criminal investigation, and so on.

DNA fingerprinting

And even the biological diversity of the human individual, in essence, is that the molecular structure of DNA differences. This use of different technicians using autoradiography and other advanced analytical tools can be drawn as a specific commodity, like the bar-code DNA map. This pattern of the individual as between people of different, like fingerprints, are highly specific and therefore referred to as DNA fingerprinting. DNA fingerprinting of the band is based on the law of the genetic parents of the transfer, in the absence of mutation, the genetic offspring of the half from the father and the other half from the mother, can not be with both parents do not have the genetic markers, son DNA fingerprinting on behalf of all the bands in all of its biological parents of DNA fingerprinting to find the appropriate location.

However, DNA fingerprints are also required larger samples are not suitable for the old, corrupt, and other samples to identify the limitations, since the 1990s, the establishment of PCR technology, DNA fingerprinting techniques to reduce the use of gradually.

PCR technology

PCR polymerase chain reaction is the acronym in English (PolymeraseChainReaction, referred to as PCR). In short, PCR is specific to the use of DNA polymerase genes do in vitro or test-tube with a large number of synthesis. It will be a limited number of DNA amplification of DNA fragments of the astronomical, can trace, old and the degradation of biological samples to do DNA analysis. At present, the technology used, for some genes can be copied to the original 10000-100000 million times. As a result, both in paleontology fossils, remains of historical figures, or a few decades ago in the homicide murderer left behind by the hair, skin or blood, as long as they can to isolate a bit of DNA, will be able to use the PCR amplification to be carried out over Right. This is also the "trace evidence" of the power lies.

Forensic PCR technology, the main features are: high sensitivity for trace, corruption and the old samples to identify, specific, simple, short-cycle testing, equipment not ask for much, easy-to-promotion.

Mitochondrial DNA sequencing technology

Mitochondria also contain DNA, mitochondrial DNA is located in the cytoplasm, with the genetic cytoplasm and at the same time it is maternally inherited. Mitochondrial DNA testing law, that is, for single-parent matriarchal paternity testing to identify the individual, and so on. A typical example is the U.S. Army DNA Identification Laboratory wars of the remains of soldiers killed in the identification of personal identification.

The discovery of DNA genetic markers before the forensic science major blood group serology using genetic markers, that is, the traditional blood type. DNA testing technology and a number of traditional criminal techniques, great superiority of the main problems: In many cases, despite trying to cover up criminal suspects, traces of the damage, physical evidence, but the victim's resistance, its own tension and Omissions and other circumstances, it is difficult to avoid leaving traces of blood, hair, body fluids and so on will be made available for DNA testing of biological samples, and the small amount of outdated, as well as the corruption of the old samples can be identified for DNA testing technology in the That crime across time and space to show off their capabilities, play a unique role in providing the material foundation and prerequisite.

Gene technology in the police department, and other applications, as Correctional Fue, Xiongwan grams of the sword, so that repeatedly violate the law by all kinds of criminals, but also complicated and confusing case, so as to the true colors of the incident.