FIGURE 5-41 Repair of a double-strand break by homologous recombination. For simplicity, each DNA double helix is represented by two parallel lines with the polarities of the strands indicated by arrowheads at their 3′ ends. The upper molecule has a double-strand break. Note that in the diagram of the upper DNA molecule, the strand with its 3′ end at the right is on the top, while in the diagram of the lower DNA molecule, this strand is drawn on the bottom. See the text for discussion. See T. L. Orr-Weaver and J. W. Szostak, 1985, Microbiol. Rev. 49:33.