How is "DNA fingerprinting" done?

1 Answer
Dec 21, 2016

Answer:

DNA fingerprinting is done by using several techniques, step by step. DNA fingerprinting is not at all a sequencing technique: rather it identifies repetitive sequences present in one's genome. Such repeat sequences also vary in length due to variation in number of repeats, hence called variable number tandem repeats: VNTRs.

Explanation:

DNA fingerprinting is done in many steps: it would involve

  • collection of biological sample,
  • extraction of DNA,
  • amplification of DNA in PCR machine
  • cutting the DNA in fragments,
  • arranging the fragments by using electrophoresis,
  • transferring the fragments on nytrocellulose membrane,
  • hybridising specific sequences by using radioactive probes,
  • washing the membrane before developing an X ray film.

The X ray plate will remain as a permanent genetic 'fingerprint' of the person. Such fingerprints are inherited: 50% from mother and 50% from father, hence a person could be easily identified when fingerprints are compared between parents/siblings.

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As the processes involved in fingerprinting are expensive, case studies are done in batches and individual results may come after a couuple of months.

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