Occurs in double-stranded cyclic DNA molecules having no breaks at all in either strand. If the double helix (of DNA) is wound further in the same direction as the winding of the two strands of the double helix molecule, then the circular duplex itself takes on superhelical turns. By analogy, supercoiling or superhelicity may be described as follows. A piece of rope composed of two or three smaller strands of rope are wound around each other to yield the finished rope. This is equivalent to the normal double-stranded DNA. If the ends of the rope are then joined or tied together and the resultant circle of rope is again wound in the same direction as the winding that produced the rope in the first place, supercoils will be formed and the rope will become a much thicker (supercoiled) but shorter piece of rope.