Sex Linkage

Some loci are linked on the sex chromosomes and are described as sex-linked
       Female mammals & Drosophila are XX (homogametic):
             they have two alleles for any sex-linked locus
       Male mammals & Drosophila are XY (heterogametic):
             they have a single allele for any sex -linked locus

  X-linked genes are inherited in characteristic patterns that differ between sexes

    
Ex.: Drosophila have four pairs of chromosomes
          A white-eye mutant of Drosophila was the first known sex-linked mutant (MGA2 5-08)
                  First cross: white-eyed male x red-eyed female
                  Reciprocal cross: white-eyed female x red-eyed male

    Other sex determining mechanisms exist in other species
            WZ females & ZZ males in birds          


All text material ©2006 by Steven M. Carr