Final answer:
In a laboratory setting, supercoiled DNA can be unwound by exposing it to heat or chemicals to cause denaturation and then allowing reannealing. Alternatively, enzymes known as topoisomerases, including DNA gyrase in bacteria, can enzymatically relax supercoiled DNA by cutting and re-ligating the DNA strands.
Step-by-step explanation:
Experimentally, another way to unwind supercoiled DNA outside of natural enzymatic processes is via the application of heat or chemicals to induce denaturation. When DNA is exposed to high temperatures or specific chemicals, the hydrogen bonds holding the two strands together begin to break, resulting in the separation of the strands, a process known as denaturation. Upon cooling or removal of the chemical denaturants, the separated strands can reanneal, that is they can recombine to form the double helix. This method can be used in a controlled laboratory setting to manipulate DNA supercoiling and observe changes in DNA topology.
Enzymatically, topoisomerases such as DNA gyrase in bacteria serve to relax supercoiled DNA efficiently during cellular processes like DNA replication. These enzymes act by cutting the DNA's phosphate backbone, allowing the DNA to uncoil and relieve the torsional stress before re-ligating the cut strand. Understanding how topoisomerases achieve this is pivotal for grasping how cells manage DNA supercoiling under various conditions.