Arrange the given steps of DNA finger-printing technique in correct sequence.
A. Isolation of DNA and its digestion by restriction endonuclease
B. Separation of DNA fragments by electrophoresis
C. Hybridization with labelled VNTR probe and autoradiography
D. Blotting of separated DNA fragments to synthetic membrane
Choose the correct answer from the options given below.
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → A, B, D, C
A. Isolation of DNA and its digestion by restriction endonuclease — first. The DNA is cut into fragments.
B. Separation of DNA fragments by electrophoresis — second. The fragments are separated by size in a gel.
D. Blotting of separated DNA fragments to synthetic membrane — third. The fragments are transferred to a nitrocellulose or nylon membrane (blotting).
C. Hybridization with labelled VNTR probe and autoradiography — last. The probe binds only to matching VNTR fragments, and autoradiography shows them as dark bands.
NCERT Extract:
DNA Fingerprinting – “… 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.”