Daisy chaining DNA
Daisy chaining DNA is when DNA undergoing PCR amplification forms tangles that resemble a 'daisy chain.' During PCR, primers or dNTP's will eventually be used up and limit further reactions. The depletion of primers causes daisy chaining; since the denaturing and annealing processes will still continue without primers, the single-stranded DNA molecules will reanneal to themselves. However, this reannealing does not always occur with another complementary strand. It is this imperfect match up that causes 'tangles'.
