Which one of the following techniques is used for the separation of DNA fragments?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Gel electrophoresis
Option (1) Polymerase Chain Reaction (PCR) — Incorrect. PCR makes many copies of a piece of DNA outside the body, using primers and a heat-stable DNA polymerase. It increases the amount of DNA. It does not sort fragments from one another.
Option (2) MRI — Incorrect. MRI (magnetic resonance imaging) uses strong magnetic fields and non-ionising radiations to picture the inside of the body. It is used to detect cancers, not to handle DNA.
Option (3) Gel electrophoresis — Correct. DNA fragments carry a negative charge, so an electric field pulls them through the agarose gel towards the anode. The gel acts like a sieve, so fragments of different sizes stop at different places.
Option (4) ELISA — Incorrect. ELISA (enzyme linked immunosorbent assay) works on the antigen-antibody interaction. It detects an infection from the antigens or antibodies in a sample. It does not separate DNA.
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NCERT Extract:
Restriction Enzymes – …
