total RNA Extraction gel control - (Nov/29/2011 )

I was trying to isolate total RNA from tumor samples and when i ran the extracted samples on gel, i saw 4 bands instead of classic 3 bands which you get to see after total RNA isolation. I believe that the presence of a 4. band is due to the existence of genomic DNA along with total RNA, since i didnt use DNase and some of the samples show up as smears, which i thought is a result of degradation. But i would like to hear your comments.

If you do your extractions well enough you may well see other bands in a RNA extraction, these are also the so called sedimentary (e.g. 28s 18s RNA bands you see normally).

Genomic DNA may show up as bands but usually it is a high molecular weight smear in the top of the gel. Smearing lower in the gel is probably degraded RNA or perhaps mRNA.