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DNA backbone breakage

Genetics as it applies to evolution, molecular biology, and medical aspects.

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DNA backbone breakage

Postby Newyorker » Mon Oct 04, 2010 4:39 pm

Hi,

As DNA denatures as a result of being heated up, could the backbone also break, or is it just the two strands that separate?

Are there any instances where the DNA backbone does break? I know that the bonds between the phosphates and OHs are very strong, and you always hear about the bases separating but not the backbone (which is on the outside, so it should make sense that the separating force will get to it first). When IS the DNA backbone attacked? Have there been studies done that specifically target the strength of the DNA backbone and its ability to hold out against damaging forces?

Thank you! :)

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Postby canalon » Mon Oct 04, 2010 5:37 pm

Just heating should normally not degrade the backbone, so only the 2 strands will separate. In order to cut the backbone:
- restriction enzymes will cut it in specific sites
- shearing forces or other mechanical forces can do it too (at no specific site though), that is why it is not recommended to vortex minipreps after the lysis step.
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Re: DNA backbone breakage

Postby kanagasundar » Tue Oct 05, 2010 3:54 am

DNA consist of three component i.e., Sugar (deoxyribose), Base ( Purine and Pyridine), Phosphate group. DNA backbone made up of alternative sugar and phosphate are held together by Phosphodiester bond. Phosphodiester bond is a covalend bond, so energy is required to more for breaking phosphodiester bond. Two strands are held together by weak bond i.e., "Hydrogen bond". This bond can easily disturb by heat, as compare to DNA backbone. In the phosphodiester bond has phosphate group bear negative charge. This -ve charge compensated by basic protein histone (made up of arginine And lysine and histine.) When their "ph" change disturb the DNA backbone. But i don't know that fully disturb, I think not fully disturb because presence of phosphodiester bond.

Various restriction enzyme cut DNA backbone at specific sites.
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Postby JackBean » Tue Oct 05, 2010 11:13 am

if you're talking about the standard denaturation in PCR like 95°C for 3 minutes, that should be fine, of course, prolonged heating or even higher temperatures could cause some damage
http://www.biolib.cz/en/main/

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Postby kanagasundar » Tue Oct 05, 2010 1:29 pm

Is any method there for separating DNA backbone without damage or little damage?
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Re:

Postby canalon » Tue Oct 05, 2010 1:51 pm

kanagasundar wrote:Is any method there for separating DNA backbone without damage or little damage?

separate the back bone from what?
OPening the double helix? just heat
Removing the bases from the backbone? No clue...
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