Template titration

Aníbal Acuña aacuna152 at gmail.com
Tue Jun 27 12:58:40 EST 2006

I need some advice:

I performed a PCR analysis using Taq polymerase (1.0 U), primers (0.5 ul
each), dNTPs (0.2mM each), MgCl2 (2mM), and increasing amounts of gDNA for
the titration (10 copies, 1E3 copies, 1E6 copies, etc).

The PCR products were separated in an agarose gel electrophoresis. My
results showed an increase of the amount of product, as the amount of
template added gets higher. But then, with higher gDNA amounts (over 1E6
copies), bands of higher molecular weight appear (the product is there

How can I explain the appearance of those unexpected bands?. Why is it that
if I increase the amount of gDNA, those bands disappear?


Aníbal Acuña.
Biochemistry student.

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