Supercoiling occurs in :

Supercoiling occurs in both Prokaryotes & Eukaryotes. Supercoiling is because of dsDNA & dsDNA is present in Both Prokaryotes & Eukaryotes. Supercoiling means a segment of dsDNA is wound nearly twice, causing supercoiling. Eukaryotes have closed, circular, dsDNA molecules in their mitochondria, as do plant chloroplasts. A prokaryotic organism typically contains a single, circular, dsDNA molecule. [Note: Circular DNA is "supercoiled", that is, the double helix crosses over on itself one or more times. Supercoiling can result in over winding (positive supercoiling) or under winding (negative supercoiling) of DNA.