A chromosome map of a species that shows the specific physical locations of its genes and/or markers on each chromosome. Physical maps are particularly important when searching for disease genes by positional cloning strategies and for DNA sequencing.

Dr. Eric Green, of the National Human Genome Research Institute's Genome Technology Branch, defines physical map.

Related terms: bacterial artificial chromosome (BAC), chromosome, deoxyribonucleic acid (DNA), DNA sequencing, gene, genetic marker, Human Genome Project, mapping, positional cloning, yeast artificial chromosome (YAC).