The five histone molecules are the major proteins that associate with DNA to form nucleosomes. In this experiment, students isolate nuclei from chicken erythrocytes and then prepare nucleosomes from the erythrocytes by using a simple procedure that employs micrococcal nuclease. They then determine the molecular weights of the five histone proteins by comparing their migration on SDS-polyacrylamide gels to the migration of standard proteins of known size. This exercise requires a single two-three hour lab session and a microcentrifuge is required. The exercise provides a fine introduction to the nucleosome structure of chromatin and typical results are shown on the gel.