Question

Given below is the diagram representing the observations made for separating DNA fragments by Gel electrophoresis technique. Observe the illustration and answer the questions that follow:

1. Why are the DNA fragments seen to be moving in the direction A → B?
2. Write the medium used on which DNA fragments separate.
3. Mention how the separated DNA fragments can be visualised for further technical use.

Answer 1

1. In gel electrophoresis, DNA molecules migrate in the direction of electrode bearing opposite charge on the basis of size. The smaller the fragment, the farther it moves.
2. The most commonly used medium or matrix is agarose which is a polysaccharide extracted from sea weeds.
3. The separated DNA fragments can be seen only after staining the DNA with a compound known as ethidium bromide followed by exposure to UV radiations as bright orange coloured bands.