Question

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

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

Answer 1

Answer: (A)

D, C, A, B

• Shorter lengths of DNA move faster than longer lengths so move further in the time the current is run. So, since D has the heaviest weight (implying it has the longest strand), it will tend to remain far from the anode. B being a lightest fragment moves farthest from the cathode.
• Hence The positions of these fragments from cathode to anode sides of the gel would be D, C, A, B,
• So,the correct answer is 'D,C,A,B'.