Question

Name and describe the technique that helps in separation of DNA fragments.

Answer 1

The fragments can be separated by a technique called gel electrophoresis.

Steps are as follows:

• Step: 1. The DNA fragments are loaded on a gel or matrix and an electric current is applied. The most commonly used matrix is agarose which is a natural polymer extracted from seaweeds.
• Step: 2. Since DNA fragments are negatively charged they move towards the positive charge i.e. anode under an electric field through a gel.
• Step: 3. The DNA fragments move through the gel and separate according to their size. The bigger ones move slowly and the smaller ones move faster.
• Step: 4. The separated fragments can be visualized after staining the DNA with Ethidium bromide followed by exposure to UV radiation. The DNA fragments can be seen as bright orange coloured bands in UV light.
• Step: 5. The separated bands are cut from the agarose gel and extracted from the gel piece.
• Step: 6. DNA fragments purified in this way are used for constructing rDNA after joining them with cloning vectors.