With the ability to isolate and analyze portions of the genome, came the ability to construct maps of genomic features. Genome mapping has been divided into two separate but complimentary approaches, genetic mapping and physical mapping. Genetic mapping, which includes pedigree analysis and cross-breeding experiments, can be used to identify the location of a genetic feature within a genome. Genetic mapping relies on known markers, including restriction fragment length polymorphisms (RFLP), single sequence length polymorphisms (SSLP), and single nucleotide polymorphisms (SNP), and the ability to place them in order according to their appearance on a chromosome. Both polymerase chain reaction (PCR) and Southern hybridization are valuable techniques for developing genetic maps. Genetic mapping is capable of developing a low resolution chromosomal map. Physical maps rely on the detection of DNA sequences and their relative positions to provide a higher resolution map of DNA molecules. Most valuable of the arsenal of physical mapping techniques are restriction mapping and fluorescent in situ hybridization (FISH). With restriction mapping, it is possible to discriminate the base-pair level differences between two segments of DNA. FISH is a form of optical mapping, where the physical position of a genetic sequence is directly visualized.
- Brown, T.A., Genomes 3, Wiley-Liss