Arrange the given events of DNA fingerprinting in correct sequence.
A. Transfer of separated DNA fragments to nitrocellulose membrane
B. Isolation of DNA and its digestion with restriction endonuclease
C. Hybridisation using probe and detection of hybridised DNA fragments by autoradiography
D. Separation of DNA fragments by electrophoresis
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → B, D, A, C
(B) Isolation of DNA and its digestion with restriction endonuclease — this comes first. The DNA must first be taken out of the cells. Restriction endonucleases then cut it into fragments.
(D) Separation of DNA fragments by electrophoresis — this comes second. The fragments are negatively charged. They move through a gel under an electric field and are sorted by size.
(A) Transfer of separated DNA fragments to nitrocellulose membrane — this comes third. The separated fragments are blotted from the gel to a membrane, so that they can be tested with a probe. This is possible only after they have been separated.
(C) Hybridisation using probe and detection of hybridised DNA fragments by autoradiography — this comes last. The labelled probe sticks to the matching fragments on the membrane. Autoradiography then shows where the probe has bound.
Note: A similar question was also asked in CUET (UG) 2023 on 23-06-2023 (Slot 3) and on 22-05-2023 (Slot 1).
NCERT Extract:
DNA Fingerprinting – …
