DNA interval genetic marker role location on genetic physical map location on linkage map genetic marker A genetic marker is a gene or DNA sequence with a known location on a chromosome that can be used to identify individuals or species. It can be described as a variation (which may arise due to mutation or alteration in the genomic loci) that can be observed. A genetic marker may be a short DNA sequence, such as a sequence surrounding a single base-pair change (single nucleotide polymorphism, SNP), or a long one, like minisatellites. genetic marker sounds as a role http://en.wikipedia.org/wiki/Genetic_marker genetic marker probe genetic polymorohism