DNA question

[MadHatter]

What is the magnitude of the electrostatic force binding a strand of DNA together?

I'm not joking here... this seriously is puzzling me.

[Duck Duck Goose]

Do you need more work to do? I can find something for you to do...
;)

[bibliophage]

I don't know if this is exactly what you're looking for, but a text I have says that ultraviolet radiation more energetic than 300nm is likely to destroy the bonds of DNA, but less energetic UV radiation is not. That's about 4 electron-volts of energy.

[Smeghead]

Well, I don't have any hard numbers and don't feel like looking them up, but DNA strands are held together by hydrogen bonds between matching bases. A-T pairs have two hydrogen bonds, and C-G pairs have three. So if you want a number for a specific strand, you'd need to know the base composition, because it varies. It's a commonly used fact that strands with lots of C-G pairs are harder to separate than strands with lots of A-T pairs.

[Alphagene]

DNA from various sources also have specific "melting" temperatures or Tm. In this context, the melting point is the temperature at which the two strands separate. DNA that has a lot of G's and C's have relatively high Tm's, for the reasons Smeghead mentioned. Tm is important for PCR, where DNA needs to be split in order for it to be replicated.

I don't have actual values of Tm on hand, however.