Chapter 11 Summary

The topics covered in this chapter can be summarized as follows:

• A genetic map (or recombination map) is a representation of the linear order of genes (or loci), and their relative distances determined by crossover frequency, along a chromosome.
• Recombination frequency is usually proportional to the distance between loci, so recombination frequencies can be used to create genetic maps.
• Recombination frequencies tend to underestimate map distances, especially over long distances, since double crossovers may be indistinguishable from non-recombinants.
• Three-point crosses can determine the order and map distance among three loci.
• In three-point crosses, a correction for the distance of the outside markers can be made to account for double crossovers between the two outer loci.
• Interference is used to describe the degree to which one crossover interferes with other crossovers in the region at the chromosome in question.