Question

What is the criterion for the movement of DNA fragments on agarose gel during gel electrophoresis?

• A. The larger the fragment size, the farther it moves
• B. The smaller the fragment size, the farther it moves
• C. Positively charged fragments move to farther end
• D. Negatively charged fragments do not move

Answer 1

The correct option is B The smaller the fragment size, the farther it moves

DNA fragments can be separated by a technique known as gel electrophoresis.

In this technique, DNA molecules which are negatively charged are separated by forcing them to move towards the anode under an electric field through a medium/matrix such as agarose.

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.