Question

A molecular technique that relies on the fact that DNA is negatively charged, and which is used to separate DNA fragments by size is called __________________________________________.

Answer 1

Agarose gel electrophoresis

Gel electrophoresis is the technique of separation of molecules on the basis of their size and charge under the application of an external electric field. It is of two types, agarose gel electrophoresis and sodium dodecyl sulfate polyacrylamide gel electrophoresis.

Agarose gel electrophoresis is used for the separation of DNA on the basis of size and charge. The gel acts as a molecule sieve which helps in the separation of fragments. DNA is negatively charged because of the presence of negatively charged phosphate group. Therefore it moves towards the positively charged electrode during electrolysis. So the separation takes place on the basis of size now. Smaller the size of the fragment, fastest it moves on the gel and farthest it appears from the loading well.

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