Question

The technique of transferring DNA fragment separated on agarose gel to a synthetic membrane such as nitrocellulose is known as

• A. Northtern blotting
• B. Southern blotting
• C. Western blotting
• D. Dot blotting

Answer 1

The correct option is B Southern blotting

Blotting techniques are used to transfer nucleic acids from gels, after gel electrophoresis, to membranes for further analytical studies. Southern blotting is used for transfer of DNA from agarose gels to membrane to analyze their composition. For the purpose, the agarose gel is mounted on filter-paper wick and the hybridization membrane is sandwiched between the gel and any absorbent material, which draw the transfer buffer through the gel by capillary action. The buffer flow draw the DNA molecules which are then immobilized on the synthetic membrane. Northern blotting is used for RNA analysis; the absorbent material is different in both techniques. Western blotting is the technique used to transfer proteins from acrylamide gels to membranes. For the purpose, electrophoresed protein bands from a polyacrylamide gel are transferred on to nitrocellulose or nylon membrane, to which they bind strongly. Dot blotting includes direct application of a mixture containing the molecule to be detected on a membrane as a dot followed by their spotting directly onto the membrane or paper substrate. This differs from the other blotting techniques because the samples are not subjected to electrophoresis. Correct answer is B.