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Wikipedia, for example, refers to DNA as "a" molecule, not two separate molecules forming a double-helix structure. Isn't this technically incorrect? There are two separate polynucleotide strands (each that can be considered one molecule on its own as the monomers are joined together by covalent bonds), and the strands joined together by hydrogen bonds and not covalent/ionic bonds along their length. Doesn't that exempt them from being considered one molecule, as the bonds joining them are intermolecular and not covalent or ionic?

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  • $\begingroup$ If we considered a double-helix to be two separate molecules, then how do describe two separate double-helices? I think using the singular "molecule" with a double helix is appropriate because it makes it easy to use the plural "molecules" when referring to a group of DNA double-helices. Also, there are other supramolecular complexes such as Catenanes and Rotaxanes which are generally referred to as singular molecules despite having no covalent bonds between the parts. $\endgroup$ – user137 Jun 6 '19 at 8:28
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    $\begingroup$ DNA is a molecule. dsDNA is a supramolecular structure. Wikipedia is not the authority on biochemical nomenclature. You can edit Wikipedia to correct this. $\endgroup$ – WYSIWYG Jun 6 '19 at 8:28
  • $\begingroup$ I'm voting to close this question as off-topic because it is about the correctness of a wikipedia article. The question may also become invalid if wikipedia is corrected. $\endgroup$ – WYSIWYG Jun 6 '19 at 8:32
  • $\begingroup$ Also, it is a possible duplicate of biology.stackexchange.com/q/66343/3340 $\endgroup$ – WYSIWYG Jun 6 '19 at 8:43
  • $\begingroup$ Wikipedia was just an example. The answers to the question linked seem to say that DNA is one molecule. The text referenced in Charles' answer (Molecular Biology of the Cell) says one, single DNA molecule is 2 polynucleotide chains, just like Wikipedia. I find the answer abut DNA being a polyatomic ion/2 polyatomic ions to be the most accurate, since a molecule is by definition uncharged (or only partially charged). $\endgroup$ – Bill Wilson Jun 7 '19 at 12:50

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