Does each chromosome in a human cell contain one complete DNA molecule, so that there are 46 separate DNA molecules, one for each chromosome? Or does a single DNA molecule continue as an extended filament, running in and out of one chromosome, then proceeding to the next–eventually threading its way through all 46 chromosomes?
There are actually 92 separate DNA molecules.
Your first explanation is correct but 1 double helix of DNA is strictly speaking composed of 2 DNA molecules attached by hydrogen bonds (and a lot of them)
Thank you very much, Canalon. However, I do question your notion that DNA should be counted as two molecules. The joining by hydrogen bonds qualifies the structure as a single molecule. By that reasoning you would always be looking at the vast number of single complex molecules that can be recognized as combinations of molecules.
I think I recall reading Watson’s DNA book and his specifically refering to DNA as a single molecule. I’m certainly no expert on this stuff, so maybe someone else will jump in.
Still, I really appreciate you clearing up my confusion over the extent of the DNA double helix as it relates to the chromosomes.
Well that is how I was taught chemistry: molecules are composed of atoms with atomic bond. If you disagree, I have no problem with that, that is why I explained my self, rather than being my usually man of a few words when it comes to such questions.
Canalon, we are definitely on the same page with your characterization of a molecule. In this instance I would say that it is the totality of all bonded atoms of the double helix that make DNA a single molecule.