When separating DNA fragments by gel electrophoresis, what is the purpose of including molecular weight markers?
A. Markers are needed to estimate the relative charges on each of the restriction fragments.
B. Markers ensure that fragments having a greater molecular weight migrate at the same rate as those having a lighter molecular weight.
C. Markers provide an indication as to the total number of restriction fragments on the gel.
D. Markers are used as a control to determine the relative size of restriction fragments.
Answer: D
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