The analysis of diverse polymorphic DNA sequences of DNA sample is called DNA fingerprinting. DNA fingerprinting is based on restriction fragment length polymorphism RFLP, polymerase chain reaction PCR, dot blot assay and determination of base sequence. Alec Jeffrey 1985 first of all developed this technique. DNA fingerprinting is not only useful in solving parental disputes but it is also an important tool in criminal investigations.
In human DNA, few sequences of nucleotides repeatedly occur. These sequences may be many bases long. The frequency of these sequences is different in different individuals. The hypervariability of DNA depends on the number of nucleotides present in these areas and their repetition. These areas are called variable number tandem repeat VNTR loci. Microsatellites and minisatellites are included in VNTR. Microsatellite repeats are 1-6 bp long while minisatellites are up to 1 kbps long. VNTRs are used in DNA fingerprinting.
Technique of DNA Fingerprinting
For DNA fingerprinting about 1 microgram DNA is required which can be obtained from blood, skin cells, semen or hair follicles. The process of DNA fingerprinting can be divided into the following steps:
Now DNA is extracted with the help of phenol. Nowadays DNA is extracted from the cells by high-speed refrigerated centrifuge. If the DNA is present in limited amount then it is amplified by making many copies of it by a polymerase chain reaction.
Applications of DNA fingerprinting
The applications of DNA fingerprinting are as follows:
Hakimuddin Kuwakhedawala is based in India with over 15 years experience as a teacher. Teaching and writing are his passion. Most of the articles of Hakimuddin are related to education, exam, environmental problems, etc.
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It is a highly technical writeup presented by the author in a simple language. Overall an informative article about DNA fingerprinting. Some of the abbreviations and units are not very clear and it would have been better if the author had given their full forms.
DNA fingerprinting has evolved as a modern method in various areas including the forensic investigations which are crucial in unearthing the truth in complicated cases. Just as two fingerprints are not similar in the same way, the two DNA patterns are also not similar. So this has been a great scientific method for identification of the person whose blood samples are got for analysis.