How do gels separate biological molecules?

Question

Please give details.

Answer 1

By electrophoresis. You put a protein, for example, in a gel of polyacrylamide. Then you appy a high voltage to the gel. According the the protein and its counterion, the various proteins separate themselves be traveling faster or slower through the gel.

Answer 2

May be you are talking about Gel permeation,there are gels made from granules of polimers with different degrees of cross -linking that lets only certain size ( molecular weigth ) to enter.Those molecules that can get inside the gel granules spend more time inside it and its retention time is higher.