what dose the genomic DNA electropherogram look like? - (Nov/24/2008 )

Hi,
In electrophoresis,my genomic DNA bands are trailing and smearing.
I'm not sure if genomic DNA band is always in this way,or I have made some mistakes in electrophoresis?

-meredith

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It depends upon

1. Species
2. Method of isolation
3. Whether you have RNA in it.
4. Whether there is degradation.
5. % Agarose
6. Amount of DNA you have loaded (with more loading, you will detect even slight degradation and then worry about it)

For a pure genomic DNA, you should expect a thick single band near the well. This is slightly above the 20Kb band of your marker lane.

RNA will show up as a large blob near the end of lane.

Degraded DNA will show up as a smear, but depending upon your downstream application and amount of degradation, this may not be a problem. PCR okay. Southern not okay if degradation is too much.

Some examples:
Clean, undegraded genomic DNA


with slight degradation, and a good bit of RNA in last two lanes

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Thank you for your illumination.
My DNA is extracted by alkaline lysis,with lots of RNA in it,but seems okay for PCR,as you say.
I get the electropherogram like this:

[attachment=5610:081124_2_.jpg]

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