The procedure of physical mapping coarsely divides into two steps First large pieces of DNA (contigs), a library of cloned fragments are ordered according to their position in the genome. Different experimental techniques are used to do that. Roughly, these are clone- probe hybridization mapping, restriction mapping, radiation- hybrid mapping and optical mapping. ... Second the cloned fragments are cut by restriction enzymes, smaller DNA fragments are obtained which are sequenced in detail (shotgun- sequencing), and the overall sequence in detail is obtained by Sequence Assembly.

The process of assembling genomic DNA clones that completely cover a genetic locus. In genome projects, this is an essential prerequisite for sequencing; in positional cloning, it assists in designing a strategy to identify the gene of interest. The procedure is to screen candidate clones for a series of characteristic marker sequences, based either on satellite DNA, or on PCR-derived sequence tagged sites. Clones that share particular markers are assumed to overlap in that region, and computer analysis is used to identify the smallest set of clones that completely cover the region. --Click Here For Details

A linear map of the locations of genes on a chromosome as determined by physical detection of overlaps between cloned DNA fragments (contigs) rather than by linkage analysis. See also Cloning.