Abstract
Genetic recombination involves the exchange of genetic material between chromosomes to produce new assortments of alleles. As such, it affects one of the most fundamental and important components of heredity – the genome itself. To understand the molecular basis of recombination, efforts have been directed to try to determine how simple organisms recombine their DNA. One approach involves the development of in vitro systems in which recombination reactions can be studied using purified enzymes. Detailed studies of these systems, using enzymes isolated from bacteria and bacterial viruses, indicate the formation of unique protein‐DNA complexes. The structure of the DNA within these complexes has important consequences for the subsequent formation of recombinant products.