Take the 2-minute tour ×
Biology Stack Exchange is a question and answer site for biology researchers, academics, and students. It's 100% free, no registration required.

All the DNA extraction protocols I have seen involve adding salts to the extraction buffer. What is the purpose of the salts? What happens if they aren't included?

share|improve this question

1 Answer 1

up vote 15 down vote accepted

The role of the salt is to neutralize the charge of the DNA's sugar phosphate backbone. This makes the DNA less hydrophilic (less soluble in water).

Ethanol has a lower dielectric constant than water so it's used to promote ionic bonds between the Na+ (from the salt) and the PO3- (from the DNA backbone) causing the DNA to precipitate.

share|improve this answer
1  
since precipitation is one of the methods to purify biomolecules, which separate them from the other components in the solution. –  Ctina Feb 10 '12 at 19:59

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.