If you recall, the major difference between eukaryotic and prokaryotic cells is the presence of an internal membrane system in the former (Nov 3, cell design 101.1).
This internal membrane system encloses the various metabolic centers and separates them into organelles. It also encloses the genetic material and we now recognize a nucleus in eukaryotic cells.
So, what is the advantage of this kind of design?
Well, as Sherlock Holmes would say, “elementary my dear Watson, elementary”. Just think about it, the genetic material contains the ‘blueprint’ of the cell’s life. So it’s but natural to ensure its safety, right?
The cell cannot leave its 'blueprint' lying around, exposed to all the enzymes and activities going on in the various metabolic centers. What if an enzyme will act on it and split it into pieces? What if it suddenly gets entangled in all the activities going on? The information in the blueprint might be destroyed or lost.
Now, do you wonder why prokaryotic cells mutate so fast? Their genetic material is not protected like that of eukaryotic cells.