The process of determining the human genome involves first mapping, or characterizing the chromosomes. This is called a physical map. The next step is sequencing, or determining the order of DNA bases on a chromosome. To sequence the human genome, maps are needed. Physical maps are used to describe the DNA's chemical characteristics.
Genetic markers are invaluable for genome mapping.
Markers are any inherited physical or molecular characteristics that are different among individuals of a population. RFLPs reflect sequence differences in DNA sites that can be cleaved by restriction enzymes. VNTRs are prevalent in human DNA and can exist in wide variance of numbers. This variability gives individuals unique VNTR regions. Used in RFLP markers are restriction enzymes.