The damage arising when copying the DNA is repaired with recombination, involving the BRCA1 and BRCA2 proteins.

This recombination event happened when the temperature was around 3000 K or when the Universe was approximately 379,000 years old.

Homologous recombination is also used in horizontal gene transfer to exchange genetic material between different strains and species of bacteria and viruses.

Thus, only the tumor cells will have a non functional recombination pathway and rely completely on PARP to repair single strand breaks before copying the DNA.

ES cells are also a useful tool in chimeras because genes can be mutated in them through the use of homologous recombination, thus allowing gene targeting.

But cells with mutated BRCA1 or BRCA2 genes are unable to undergo recombination and are therefore much more sensitive to an increased level of unrepaired single strand breaks.

Mutational processes are far more complex than was thought a few decades ago with strand slippage, duplication, transposition, and illegitimate recombination producing qualitative differences between closely related genomes.

The reason is simple cells that have recently lost the functional BRCA1 or BRCA2 allele and that will later grow into tumors will also be unable to undergo recombination.

'Modern biotechnology' is defined in the Protocol to mean the application of in vitro nucleic acid techniques, or fusion of cells beyond the taxonomic family, that overcome natural physiological reproductive or recombination barriers and are not techniques used in traditional breeding and selection.

Within a short while, I think there's going to be a new field called Combinatorial Genomics, because with these new synthesis capabilities, these vast gene array repertoires and the homologous recombination, we think we can design a robot to make maybe a million different chromosomes a day.