Synteny between human and mouse chromosomes
Synteny is the homology
between chromosome regions
of different species. Syntenic relationships were originally determined
by comparison of recombination maps for homologous loci among species:
these studies showed that many loci were in the same relative order
across species. The diagram shows the alignment of two mammal species,
the 2n=46 human chromosomes on
the 2n=40
mouse chromosomes. Note that gene regions tend to remain together in
large blocks, rather than being intermingled. For example, as indicated
by the red bars, the human Chromosome
1 occurs in two large blocks, corresponding to the short and
long arms of mouse Chromosomes 1
& 4 respectively, with a small bit on mouse Chromosome 8. The X & Y chromosomes
of the two species are almost entirely homologous, as expected because
the the basic sex-determining genetic mechanisms is shared by all
mammals.