In the technique of DNA fingerprinting as it was initially developed, which DNA was used as the probe?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Satellite DNA showing a very high degree of polymorphism (VNTR)
DNA fingerprinting compares the DNA of two people. It looks at repetitive DNA, where a short sequence is repeated many times. Some of this repetitive DNA forms a separate band during density gradient centrifugation and is called satellite DNA. Satellite DNA shows a very high degree of polymorphism: the number of repeats differs from person to person. As the technique was first developed, a satellite DNA was used as the probe. It was called VNTR (Variable Number of Tandem Repeats), and the radiolabelled VNTR probe was used in Southern blot hybridisation.
NCERT Extract:
DNA Fingerprinting – “… The technique of DNA Fingerprinting was initially developed by Alec Jeffreys. He used a satellite DNA as probe that shows very high degree of polymorphism. It was called as Variable Number of Tandem Repeats (VNTR). The technique, as used earlier, involved Southern blot hybridisation using radiolabelled VNTR as a probe.”