DNA from Agarose gel basic questions - Basic functions of chemicals in DNA extraction from Agarose Gel (Jan/29/2008 )

Hi dear friends,
I have a query regarding what do the different chemicals serve for during the extraction of DNA from agarose gel.

1) First of all : Adding Phenol : Chloroform ?
2) Adding 100 % Ethanol and Natrium-acetate?
3) Adding 70 % ethanol?

take care.

1) to extract the dna from the gel

2) to precipitate dna from the solution

3) to wash the salt out of the dna pellet

then you resuspend in water, te or tris (depending on your purpose)

You don't need Ph/Chl to extract DNA fragment from agarose gel. Use the simple freeze-thaw method: run low melting gel in TAE - cut out the band - melt it at 70*C - freeze at -80*C for 15min - spin at RT to pellet gel - take supernatant directly to ligase reaction.