Physical breakage of
the DNA molecule in two
non-homologous chromosomes can produce "sticky ends" that recombine end-to-end (top
right). The broken ends of the chromosomes lack centromeres, and
are lost during cell division as acentric fragments.
In a standard metaphase chromosome
spread, the joined chromosomes are replicated and appear as a
single chromosome with two centromeres.
At mitosis or meiosis, the two centromeres may segregate together
to the same pole so as to produce a product a more or
less complete gene set. Alternatively, they may segregate to alternate
poles, in which case the region between the two centromeres
will be broken at random, and produce segmental aneuploidy
in the daughter cells.