Mention the steps involved in DNA fingerprinting.

Explanation

Dr. Alec Jeffreys developed the technique of DNA finger printing an attempt to identify DNA marker for inherited diseases. DNA finger printing uses short nucleotide repeats called Variable Number of Tandem Repeats (VNTRS) as markers.
VNTRS vary from person to person.
Methodology:
1. DNA is isolated and extracted from the cell or tissue by centrifugation.
2. By the process of polymerase chain reaction (PCR) many copies are produced, this step is called amplification.
3. DNA is cut into small fragments by treating with restriction endonuclease.
4. DNA fragments are separated by agarose gel electrophoresis.
5. The separated DNA fragments are visualized under ultraviolet radiation after applying suitable dye.
6. The DNA is transferred from electrophoresis plate to nylon membrane sheet. This is called southern blotting.
7. Probes are now added which bind to specific nucleotide sequences that are complementary to them this is called hybridisation.
8. The hybridised DNA fragments are detected by autoradiography. They are observed as dark bands on x-ray film.