RNA Question

[Edouard Lauzier]

When I use The Chomczynski and Sacchi method for RNA extraction...

1. The homogenizer will shear DNA,  but why the latter goes to the
interface and/or the organic phase ?  Since it does not shear the RNA, the
"sheared"  DNA must be approximatly the same size.  What affects the DNA
that doesn't affect the RNA  ( Na acetate ?, phenol pH ? ... ) ? 

2.  When they say resuspend the pellet with 75% ethanol do they mean
vortex,  just a little shake, good wash etc ?  Is it a critical step and
why ?

Sorry again for all those basic questions but help is badly needed...

Bye
-- 
Edouard Lauzier, B.Sc.                           elauzier at fse.ulaval.ca
Physical Activity Science Laboratory       (418) 656-2131 #2929
(Laval University)  G1K 7P4
CANADA