FIG. 1.
Genetic assays for recombination. (A) Selection of heteroallelic recombination. Here, a functional LEU2 gene results from a conversion event not associated with crossing over. (B) Gene conversion associated with crossing over. (C) The LEU2 recombinant gene results from a reciprocal crossover event without any detectable gene conversion. (D) Assay for loss of heterozygosity. This results in Leu− cells. The event described here corresponds to a gene conversion with crossing over. (E) Loss of heterozygosity can also occur by reciprocal exchange between the centromere and the marker during the G2 stage, followed by segregation in the next cell division.