What is the purpose of a restriction enzyme in an electrophoresis gel?
To cut DNA, RNA, or plasmid at restriction sites (like EcoRI, BamHI, hindIII and BglII) to create smaller genetic fragments that can be separated and thus characterized using gel electrophoresis.
There exist an enzyme, called restriction enzyme, that can identify a particular nucleotide sequence, called restriction sites, and perform cleaving operation. This process separates genetic material into smaller fragments which may contain gene(s) of interest. Information on the size of the fragment can be achieved through the use of gel electrophoresis.