Abstract
DNA synthesis that occurs during repair is much less accurate than normal DNA replication. Using the yeast mating type switching system, Haber’s lab identified base pair substitutions, frame shifts and other mutations that occur when the newly synthesized strand dissociates from the template strand during homologous recombination. Interestingly, Haber found that sometimes the newly synthesized strand will “jump” to a related but divergent template, even on another chromosome, and then jump back to complete the repair. Further experiments showed that this happens because the repair polymerase falls off the template with a very high frequency. Understanding why this occurs may help us to decipher the complex chromosomal rearrangements associated with certain human diseases.