Chromosomal aberrations:
(1) The structural, morphological change, which take place in chromosome due to rearrangement, is called chromosomal aberrations.
(2) The aberrations change the sequence of the genes. This causes variations. Chromosomal aberrations are mainly of following four types:
1. Deletion : Loss of genes from chromosome.
2. Duplication : Genes are repeated or doubled in number on chromosome.
3. Inversion : A particular segment of chromosome is broken and gets reattached to the same chromosome in an inverted position due to 180° twist. There is no loss or gain of gene complement of the chromosome.
4. Translocation : Transfer or transposition of a part of chromosome or a set of genes to a non-homologous chromosome is called translocation. It is effected naturally by the transposons present in the cell.
