Talk:DNA supercoil

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This article shuold replace "supercoil" as its more specific. Supercoil doesn't neccessarily refer to DNA. The other article was merged with this one when I edited it. I attempted to remove the one titled "supercoil" but I'm not sure how to do that.

Supercoil vs. supercoiling

What is the difference between these two terms? Can it be said that for circular closed DNA, supercoil corresponds to writhe (need not be a natural number) and supercoiling corresponds to linking number (must be natural number), and twist corresponds to how many twists of double DNA helix occur per whole circular DNA (need not be a natural number). Kazkaskazkasako (talk) 16:28, 12 December 2007 (UTC)

That's right, the use of some expressions in this article is very confusing. In the third paragraph Supercoil is said to be the same as writhe, whereas in the forth, Supercoiling is defined as the sum of twists and writhes. I suggest using the term Linking number instead as defined in the section DNA topology of the article DNA structure rather than Supercoiling. In that section Linking Number (L) is defined as the number of times that one DNA strand wraps around the other. In such case L = T + W, where T is the number of twists and W the number of writhes. Since the article DNA supercoil defines Supercoiling (S) as sum of twist and writhe (S = T + W), I can see a clear analogy between Linking Number (L) and Supercoiling (S) (both are the result of T + W). Heathmoor (talk) 20:46, 25 February 2010 (UTC)

Is DNA in most organisms negatively supercoiled?

There's no reference for such statement and it is very imprecise. What does most organisms stand for? Prokaryotes? From the way in which the DNA wraps around nucleosome cores and the higher levels of DNA packaging it follows that nuclear eukaryotic DNA is most likely positively supercoiled. Thus, negative supercoiling would be restricted to prokaryotes with the exception of extreme thermophils, which have positively supercoiled DNA to to prevent dsDNA denaturation. Heathmoor (talk) 14:23, 26 February 2010 (UTC)

picture deleted

@Mahiganji and Daphne Lantier: The Picture is not available any more on commons[1][2] therfore here it should be deleted or substituded. User:Mahiganji: Please repair your mistake [3], as you can see in DNA_supercoil#Visualizing_DNA_supercoils:_Intercalation-induced_supercoiling_of_DNA the picture does not work.  — Johannes Kalliauer - talk | contributions 20:33, 29 June 2017 (UTC)