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Name: Ura
Status: Other
Grade:  Other
Location: N/A
Country: United States
Date: July 2005


Question:
I have some questions regarding the DNA extraction experiment from onion cells.

1)what is the purpose of the usage of salt to make the DNA extraction mix?

2)at the end of the experiment,the DNA of the onion cells will appear as a 'fluffy' white solid that floats on top of the mixture of clear liquid and ice cold 95 percent ethanol.why does the DNA floats?



Replies:
The purpose of the salt is to precipitate protein. I can't explain why the DNA is floating. In most DNA extraction methods, DNA ends up as a pellet at the bottom of the alcohol phase because it is insoluble in ethanol and has a density of approx. 1.8 g/cc.

Ron Baker, Ph.D.



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