Dna Fingerprinting

DNA fingerprinting  DNA Fingerprinting DNA Fingerprinting is also referred to as DNA profiling and DNA typing.  It was first developed as an identification technique in England in 1985. The original use was to expose the presence of any genetic diseases. About three years later it became used to identify criminals through the analysis of genetic material and to settle paternity disputes. It is still used for those reasons today.  The DNA fingerprinting process is called gel electrophoresis. It is a process that can sort pieces of DNA according to its size.  is a way of identifying a specific individual, rather than simply identifying a species or some particular trait.

DNA Fingerprinting Process The DNA Fingerprinting Process began in 1985. Genetic fingerprinting was invented by Sir Alec Jeffreys at the University of Leicester, and is used to distinguish individuals through DNA. The process begins by extracting DNA from the cells in a sample of blood, saliva, semen, or other appropriate fluid or tissue. An analysis is performed by a cut into the DNA into fragments which are separated into bands. The bands of DNA are transferred via a technique called Southern blotting. This is treated with a radioactively-labeled DNA probe which binds to certain and specific DNA sequences on the membrane. The excess DNA probe is washed off. An X-ray film placed next to the nylon membrane detects the radioactive pattern. This film is then developed to make a visible pattern of bands called DNA fingerprinting. One of the most modern and widely accepted methods for producing DNA fingerprints in criminal cases, is that of polymerase chain reaction (PCR). PCR involves the amplification of specific regions of DNA that are known to be . PCR is by far the most common method for presenting DNA evidence in a forensic context. .

Advantages of DNA Fingerprinting:

The most important advantage of DNA fingerprinting is that there is strong similarities shown between genetic fingerprints of parents and children. This is a benefit because a child's genetic fingerprint is made up of half the father's genetic information and half of the mother's information. This means that the bands of a child's genetic fingerprint will match the bands on both of their parents, making it possible to establish paternity and maternity tests. Disadvantages of DNA Fingerprinting: One of the main problems with the process of DNA fingerprinting is that the sample can be easily ruined. The tiniest pieces of genetic junk can contaminate DNA samples, causing them to be useless. Although DNA fingerprinting requires a good sample to work with, this problem can be solved by using the newer technique called PCR. PCR can use extremely small samples of DNA and produce a much faster result. But this also means the DNA samples that PCR uses are even more likely to be contaminated because of their size, as it is harder to find a small sample with hardly any contamination. Another limitation of fingerprinting is that the procedure is so complex and hard to read the DNA patterns, that sometimes the juror finds the evidence almost invisible. Although DNA Fingerprinting is a highly advanced process, there are still some things that it is unable to do. In dogs for example, a fingerprint does not make it possible to determine if the animal is a carrier of a disease causing allele. Also, a DNA fingerprint is unable to show a crossbreed in animals. This is because second or third generation crosses cannot be seen by working backwards in a pedigree. It may soon become possible to discover the crossbreed of dogs, although right now this is not possible. Technique . The AFLP technique is based on the selective PCR amplification of restriction fragments from a total digest of genomic DNA. The technique involves three steps: (i) restriction of the DNA and ligation of oligonucleotide adapters, (ii) selective amplification of sets of restriction fragments, and (iii) gel analysis of the amplified fragments. PCR amplification of restriction fragments is achieved by using the adapter and restriction site sequence as target sites for primer annealing. The selective amplification is achieved by the use of primers that extend into the restriction fragments, amplifying only those fragments in which the primer extensions match the nucleotides flanking the restriction sites. Using this method, sets of restriction fragments may be visualized by PCR without knowledge of nucleotide sequence. The method allows the specific co-amplification of high numbers of restriction fragments. The number of fragments that can be analyzed simultaneously, however, is dependent on the resolution of the detection system. Typically 50-100 restriction fragments are amplified and detected on denaturing polyacrylamide gels. The AFLP technique provides a novel and very powerful DNA fingerprinting technique for DNAs of any origin or complexity.