11. Z-DNA formation is a dynamic process, largely controlled by the amount of supercoiling . 12. Extra helical twists are positive and lead to positive supercoiling , while subtractive twisting causes negative supercoiling. 13. Extra helical twists are positive and lead to positive supercoiling, while subtractive twisting causes negative supercoiling . 14. Mathematical expressions are used to describe supercoiling by comparing different coiled states to relaxed B-form DNA. 15. In response to supercoiling , they will assume an amount of writhe, just as if their ends were joined. 16. This is done as the phage genome supercoils and the secondary structure formed by such supercoiling attracts a primosome protein complex. 17. DNA supercoiling is important for DNA packaging within all cells, and seems to also play a role in gene expression. 18. Supercoiling , packing with histones in chromosome structures, and other such supramolecular aspects also involve " in vivo"19. While topoisomerase IV does relax positive supercoils like DNA gyrase, it does not introduce further negative supercoiling like the latter enzyme. 20. The likely basis for this is that loops containing a break lose their supercoiling and become free to extend toward the anode.
