Locus

 In the study of Genetics, a locus (plural form loci) is a specific region on the chromosome where a gene or DNA sequence is located. The estimated number of haploid protein coding genes in humans is 20,000 to 25,000. Another form of a gene positioned at a given locus is called an allele. The organised list of loci recognised for a certain genome is known as a genetic map. Gene mapping is used in the determination of a locus which codes for a particular biological characteristic in an organism.