1.Introduction

Mapping of gene is done as to identify and record the exact loci of the gene; it also helps us to understand the distance present between the genes. Thus, gene mapping is considered to be the backbone for the establishment of the Human Genome Project. It provides a helping hand to the scientists in locating their path around the genetic material. Landmarks on a genome map can include short DNA sequence, control sites genetically modified shutdown and shutdown or the gene itself. The two major types of methods used for the genomic mapping is the genetic mapping and the physical mapping, both these types helps in the location of the gene present on the chromosomes. Genomic mapping plays the major role in identifying the genetic information of the genes which share among themselves in the meiosis process (cell division). The landmarks of these genes are also decided by the crossing over. However, physical mapping observes the distance between the bases in units in a physical manner of the known DNA sequence. Alfred Sturtevant was the first scientist who designed the genetic map of the chromosome of the Drosophila melanogaster (also known as Fruit Fly) in the year of 1913. He also observed that all the genes were arranged in the straight line and every gene were placed at particular places. His theory suggested that the frequency at which the crossing over takes place between the two genes helps in determining their location on the chromosomes.