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DNA fingerprinting is a hybridisation technique used to identify similarities between DNA molecules of two individuals. DNA fingerprinting was invented by Sir Alec Jeffry in 1985. DNA fingerprinting involves identifying differences in some specific regions in DNA sequence called repetitive DNA, because in these sequences a small stretch of DNA repeated many times and this called repetitive DNA.
DNA Fingerprinting
These sequences do not code for any proteins but they form a large portion of the human genome. These sequences show high degree of polymorphism & form the basis of DNA fingerprinting.
Since DNA from every tissue (blood, skin, hair, saliva) from an individual show same degree of polymorphism, they become very useful tool in forensic applications. DNA fingerprinting is a process used to determine nucleotide sequences at a certain part of the DNA that's unique in all human beings. DNA fingerprinting involves the following steps :- Sample collection DNA extractions Hybridisation Detection The DNA of the organism (host) which has to be tested is isolated, it is the host DNA. DNA can be acquired from any bodily sample or liquid, buccal smear, saliva, hair, blood etc The isolated host DNA is treated with restriction enzymes. Restriction enzymes cut DNA into small fragments. The double stranded DNA fragments are denatured to produce single stranded DNA by
from the filter. The nitrocellulose filter paper is photographed on an x ray film by autoradiography. An autoradiograph when developed reveals a unique pattern of light and dark bands that reflect the composition of DNA. The dark bands on the X ray film represents the DNA fingerprints.
Applications :-
DNA fingerprinting techniques help in the discovery of evolutionary distance existing between two adjacent groups in the evolutionary tree. In the medical field pathogens have been diagnosed by DNA fingerprinting. Eg :- Vibrio cholerea, Stephilococcus. In fosensic science DNA fingerprinting is used to solve problems of paternity, rape & murder cases.
Recombinant DNA can be identified. DNA fingerprinting helps in immigrant dispute, reuniting the lost children, archaeology and in veterinary importance.
