what is the glycine for in running and trans buffer？ - and what is the Tris for？ (Dec/04/2009 )

what is the glycine for in running and trans buffer？
and what is the Tris for？
to buffer the pH？what change the pH during the electrophoresis and transfer？the current？and why？
could you show me the recipe you used for running and trans？
thanks a lot

pH is lower in stacking gel(6.8) in comparison to seperating gel. thats why electrophoretic mobility of glycin ions in stacking gel is less than the mobility of proteins while in seperating gel the glycin ions migrate past the proteins; it helps proteins in the sample to stack when they reach the seperating gel, it means they form a narrow band.
the receipe depends on the acrylamide percentage and thus to protein size to be seperated ( higher percentage for smaller proteins) but there are numerous protocols in the internet which you can find simply by searching google