Question

DNA finger printing?
process& basis

Answer 1

Principle - Every individual (except monozygotic twins) has unique sequences called Variable Number Tandem Repeats in the DNA. When chromosomal DNA of different people are digested with restrictions enzymes, the DNA yields unique patterns which can be seen when it is subjected to gel electrophoresis.

Steps

1. Extraction of DNA,
2. Amplification of DNA using Polymerase Chain Reaction.
3. DNA is cut using restriction enzymes during a process called restriction digestion.
4. Separation of DNA sequences using gel electrophoresis.
5. Already available complementary DNA strand, called probe, is hybridised with the isolated DNA.
6. Specific bonds can then be observed by exposing the membrane to an X-ray film.