(Color online) Four microstates for nucleosome unwinding and rewinding proposed in Ref. [10]. The histone octamer is depicted as a circle. DNA is depicted as a line. For state 2, the nucleosome is fully wrapped by nearly two turns of DNA. For state 1, the outer turn is unwrapped, but the inner turn is wrapped. For state 0, both the outer and inner turns are unwrapped, but the histone octamer remains bound to the DNA. Finally, the histones may be unbound from the DNA.