Arrange the following steps in order for the technique of DNA finger printing.
A. Isolation of DNA.
B. Separation of DNA fragments by gel, electrophoresis.
C. Digestion of DNA by restriction endonucleases.
D. Blotting of separated DNA fragments to nylon membrane.
E. Hybridisation using VNTR probe followed by autoradiography.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → A,C,B,D,E
A. Isolation of DNA — first. The DNA is taken out of the cells of the sample, such as blood or hair.
C. Digestion of DNA by restriction endonucleases — second. The enzymes cut the DNA into fragments at their recognition sites.
B. Separation of DNA fragments by gel, electrophoresis — third. The fragments can be separated only after they are made. In the gel they separate by size.
D. Blotting of separated DNA fragments to nylon membrane — fourth. The separated fragments are transferred from the gel to a membrane of nitrocellulose or nylon.
E. Hybridisation using VNTR probe followed by autoradiography — last. A labelled VNTR probe binds to its matching fragments on the membrane, and autoradiography shows the band pattern.
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. It included (i) isolation of DNA, (ii) digestion of DNA by restriction endonucleases, (iii) separation of DNA fragments by electrophoresis, (iv) transferring (blotting) of separated DNA fragments to synthetic membranes, such as nitrocellulose or nylon, (v) hybridisation using labelled VNTR probe, and (vi) detection of hybridised DNA fragments by autoradiography.”