Mathews/van Holde/Ahern 3rd Edition

Figure 4.18: Relaxed and supercoiled DNA molecules.

Courtesy of Dr. D. A. Clayton.(a) Courtesy of Drs. D. Dressler and K. Koths; (b) Courtesy of R. Kavenoff, Designergenes Ltd./BPS; (c) © Biology Media/Photo Researchers.