A plasmid DNA and a linear DNA (both are of the same size) have one site for a restriction endonuclease.

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asked Mar 14 in Class XII Biology by rahul152 (-2,869 points)
A plasmid DNA and a linear DNA (both are of the same size) have one site for a restriction endonuclease. When cut and separated on agarose gel electrophoresis, plasmid shows one DNA band while linear DNA shows two fragments. Explain.

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answered Mar 14 by nikita74 (-1,051 points)

It is because plasmid is a circular DNA molecule. When cut with enzyme, it becomes linear but does not get fragmented. Whereas, a linear DNA molecule gets cut into two fragments. Hence, a single DNA band is observed for plasmid while two DNA bands are observed for linear DNA in agarose gel. 

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