molecular marker

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molecular marker Any site (locus) in the genome of an organism at which the DNA base sequence varies among the different individuals of a population. Such markers generally have no apparent effect on the phenotype of the individual, but they can be determined by biochemical analysis of the DNA and are used for a variety of purposes, including chromosome mapping, DNA fingerprinting, and genetic screening. The advent of such genetic tools as restriction enzymes and the polymerase chain reaction plus the growing abundance of DNA sequence data, coupled with automated high-throughput assays, have revealed several classes of molecular markers, including restriction fragment length polymorphisms (RFLPs), variable number tandem repeats (VNTRs), microsatellite DNA, and single nucleotide polymorphisms (SNPs).