Identify the correct sequence of events for the technique of DNA fingerprinting.
(A) Hybridization using labelled VNTR probe, followed by detection of hybridized DNA fragments by autoradiography
(B) Transfer of separated DNA fragments to synthetic membranes, such as nitrocellulose or nylon
(C) Isolation and digestion of DNA by restriction endonucleases
(D) Separation of DNA fragments by electrophoresis
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (C), (D), (B), (A)
(C) Isolation and digestion of DNA by restriction endonucleases — first. DNA is isolated and cut into fragments by restriction enzymes.
(D) Separation of DNA fragments by electrophoresis — second. The fragments are separated by size in a gel.
(B) Transfer of separated DNA fragments to synthetic membranes, such as nitrocellulose or nylon — third. The separated fragments are blotted onto a membrane.
(A) Hybridization using labelled VNTR probe, followed by detection of hybridized DNA fragments by autoradiography — last. A labelled VNTR probe binds its matching fragments, which show up on X-ray film.
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.”