Question

A mixture containing DNA fragments, A, B, C and D, with molecular weights of A+B=C, A>B, D>C, was subjected to agarose gel electrophoresis. The positions these fragments from anode to cathode sides of the gel would be

• A. B,A,C,D
• B. A,B,C,D
• C. C,B,A,D
• D. B,A,D,C

Answer 1

The correct option is A

B,A,C,D

DNA fragments are negatively charged molecules they can be separated by forcing them to move towards the anode under an electric field through a medium/matrix. Nowadays the most commonly used matrix is agarose which is a natural polymer extracted from sea weeds. The DNA fragments separate (resolve) according to their size through sieving effect provided by the agarose gel. Hence, the smaller the fragment size, the farther it moves.