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Class 12th Biology 2015 Set1 Delhi Board Paper Solution

Question 21

Following the collision of two trains a large number of passengers are killed. A majority of them are beyond recognition. Authorities want to hand over the dead to their relatives. Name a modern scientific method and write the procedure that would help in the identification of kinship.


DNA fingerprinting is the modern scientific method used for the identification of kinship. Procedure of DNA Fingerprinting

Variable Number of Tandem Repeats (VNTR) are satellite DNAs that show high degree of polymorphism.​ They are used as probes in DNA fingerprinting. Firstly, DNA from an individual is isolated and cut with restriction endonucleases. Fragments are separated according to their size and molecular weight through gel electrophoresis. Fragments separated through electrophoresis gel are blotted (immobilised) on a synthetic membrane such as nylon or nitrocellulose. Immobilised fragments are hybridised with a VNTR probe. Hybridised DNA fragments can be detected by autoradiography. VNTRs vary in size, ranging from 0.1 to 20 kb. Hence, in the autoradiogram, a band of different sizes will be obtained. These bands are characteristics of an individual. They are different in each individual, except in the case of identical twins.