. Restriction endonucleases popularly referred to as restriction enzymes, are ubiquitously present in prokaryotes. The function of restriction endonucleases is mainly. The curve on the left shows the height of a population of penguins . the curve on the right from brainly.com The restriction enzyme cleavage site is a specific site on the dna strand that has a defined sequence of nucleotides. • in nature, restriction enzymes help bacteria to ward off invasion by foreign dna. Gel eletrophoresis refers to the technique in which molecules are forced across a gel by an electrical current from activated electrodes at both ends of the gel.