Mutations - Deletion
A deletion is a mutation resulting in the loss of a segment of
the genetic material, and the genetic information contained
therein, from the chromosome. The deleted segment may be
located in the middle of the chromosome or on the end.
A deletion is initiated by breaks in chromosomes induced by
such agents as heat, radiation, chemicals, and viruses. The
consequences of a deletion depend on the gene or genes
that were removed. In this animation, the D region of the
chromosome is deleted.
In diploid organisms the effects of a deletion may be minimized by the presence of the other set of genes on the homologous chromosome. Sometimes, however, the deletion of a dominant allele on one homolog can allow harmful recessive alleles on the other homolog to be expressed in the individual as a detectable phenotypic change.