Question: 112: Separation of DNA, fragments is done by a technique known as
(1) Polymerase Chain Reaction
(2) Recombinant technology
(3) Southern blotting
(4) Gel electrophoresis
Answer: Option (4)
Explanation:
Gel electrophoresis is the technique used to separate DNA fragments based on their size.
DNA molecules carry a negative charge due to the presence of phosphate groups in their backbone.
When an electric field is applied across a gel matrix, DNA fragments migrate towards the positive electrode.
Smaller DNA fragments experience less resistance from the gel and hence move faster,
while larger fragments move more slowly.
This difference in migration rate results in the separation of DNA fragments according to their lengths.
Polymerase Chain Reaction is used for amplification of DNA, not separation.
Recombinant technology involves combining DNA from different sources.
Southern blotting is a technique used for detection of specific DNA sequences after separation.
Therefore, separation of DNA fragments is correctly done by gel electrophoresis.