Now, if the DNA molecule isn't too large we can use the polyacrylamide gel. But if the DNA molecule is very large then we have to use a gel that has larger pore size. So we normally use anguarose gel. So these are the two gels that we can basically use and the one that we use determines or which one we use is determined by the size of that initial DNA molecule. Now, so we take our fragments and we place them into the gel electrofreeze setup. And now the gel electrophoresis basically separates the DNA fragments based on size.