Exact molecular weight? - (Jun/27/2012 )
It sounds vey stupid but anyway!
My friend told me that there is difference between the protein and DNA electrophoresis-
For SDS-PAGE -- we take the top edge of bands as the exact weight of protein
For DNA - we take the bottom edge of bands as the exact weight of protein
Please clarify me on this.
I think it is irrelevant which side of the band you chose to measure from- as long as you are consistent.
So if you use the bottom edge of the band for your molecular weight standards, you use the bottom edge for your unknown samples too