A number of passengers were severely burnt beyond recognition during a train accident. Name and describe a modern technique that can help in handing over the dead to their relatives.

Purusottam Nayak · 09th Jun 2019 .

Ramesh Swain · 09th Jun 2019 .

DNA fingerprinting technology can help to identify the dead individuals. It is a technique of determining nucleotide sequences of certain portion of DNA which are unique to each individual. DNA fingerprints can be prepared from extremely minute amounts of blood, semen, hair bulb or certain other cells of the body. The major steps are as follows :

(i) DNA is extracted from the cells. It is cut into fragments with restriction enzymes. The fragments of DNA also contain VNTRs (Variable Number Tandem Repeats) which vary in number from person to person.

(ii) DNA fragments are passed through gel electrophoresis. Fragments of particular size having VNTRs are multiplied using PCR. Alkaline chemical is used to split dsDNA to ssDNA

(iii) Separated DNA sequences are transferred from gel onto a nitrocellulose or nylon membrane.

(iv) Radioactive DNA probes complementary to VNTRs are poured over the nylon membrane. Some of them bind with VNTRs (Southern Blotting).

(v) X-ray film is exposed to the nylon sheet which gives dark bands at the probe sites. Thus, hybridised fragments are detected by autoradiography. The dark bands on X-ray film represent the DNA fingerprints (DNA profiles)

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