My professor mentioned the resolution of the gel in gel electrophoresis. He stated that agarose has large pores and thus low resolution whereas polyacrylamide has the opposite. I don't understand what resolution has to do with this. Can someone explain?
Resolution size of the gel simply means the distinction that can be made between molecules very close in size.
If you were looking to distinguish between a 100bp fragment and a 200bp fragment, then agarose will give you that level of differentiation.
But if you were looking to distinguish between a 190bp fragment and a 200bp fragment then you would likely want to us polyacrylamide. The PA gel has a higher resolution because you can distinguish between smaller differences on molecule length.
Think of it in terms of a simplified idea of a microscope, at 100X, you can probably distinguish between cells, maybe make out a well stained nucleus. where as at 1000X you can start to discern other organelles. You are seeing a finer degree of detail at the higher magnification. There are many factors that go into the resolving power of a microscope and the example based on magnification is simplistic and doesn't really address optical resolution, but it is an illustrative example of resolution in a gel. You can think of agarose as the 100X and PA as the 1000x, if that helps.