Question

This segment of DNA has restriction sites I and II which create restriction fragments a, b, and c. Which of the following gels produced by electrophoresis would represent the separation and identity of these fragments?

• A.
• B.
• C.
• D.

Answer 1

Answer: (B)

In gel electrophoresis, nucleic acid molecules are separated by applying an electric field to move the negatively charged molecules through a matrix of agarose or other substances. Shorter molecules move faster and migrate farther than longer ones because shorter molecules migrate more easily through the pores of the gel. This phenomenon is called sieving.
Hence, c has been the longest fragment with high molecular weight travel a short distance, as it moves slower. a band moves faster than c and b is the shortest fragment and hence moves fastest and farther.