The identity can be established by the technique of DNA fingerprinting.
• DNA is isolated and extracted from the cell or tissue by centrifugation.
• By the process of polymerase chain reaction (PCR), many copies are produced. This step is called amplification.
• DNA is cut into small fragments by treating with restriction endonucleases.
• DNA fragments are separated by agarose gel electrophoresis.
• The separated DNA fragments are visualised under ultraviolet radiation after applying suitable dye.
• The DNA is transferred from electrophoresis plate to nitrocellulose or nylon membrane sheet. This is called Southern blotting.
• VNTR probes are now added which bind to specific nucleotide sequences that are complementary to them. This is called hybridisation.
• The hybridised DNA fragments are detected by autoradiography. They are observed as dark bands on X-ray film.
