> If you have, for instance, three incorrect copies of a DNA sequence you can compare them in order to get the original sequence. The probability that the copie

> If you have, for instance, three incorrect copies of a DNA sequence you can compare them in order to get the original sequence. The probability that the copies are damaged at the same point being very small. What are you comparing them to? Sure, we humans can do this in a lab, but in a nucleus, there is only the anti-copy of the other side of the nucleotides. Most eukaryotes just use one of their chromosomes and both are needed for mytosis/myosis. Cells have no way of knowing which copy is the 'correct' one. If there is more than one copy of a DNA strand floating about, cells really do not like this and, in many eukaryotes, will deal with it in a very complicated dance. Prokaryotes/Archea are a wildly different story however.