normal PCR - two bands is found in one sample (Mar/01/2009 )

In normal PCR, two bands is found in only one sample clearly in the middle and at the end.Which is its result.?
Please explain me.Why it is caused?

thinsu on Mar 1 2009, 03:10 PM said:

Its probably non-specific binding of primers which causes extra bands.

Does any of the bands correspond to the expected product size? If both bands are not right, then you need to optimize conditions for PCR like Mg cocentration, template, etc. .

Or may be could be supercoiled DNA, non-specific binding means low product, and many bands. You have also your template, it could be your other band, hope it helps.

thinsu on Mar 1 2009, 06:10 AM said:

If the band at the end is less than 100 bp, it is likely primer dimers.