Monomorphic markers

A DNA marker is simply a uniquely identifiable segment of DNA. There are several different types of markers, usually ranging in size from one to 300-400 nucleotide bases in size. Markers can be thought of as landmarks, and a set of markers whose relative positions (or order) within a genome are known comprises a map. Markers can be categorized in several ways. Some markers are polymorphic, and others are not (monomorphic). Detection of markers may be either PCR based or hybridization based. Some markers lie in a sequence of DNA that is expressed some do not, or their expression status may be unknown. 

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