The transfer of a segment of chromosome to a non- homologous chromosome is called translocation. Translocation should not be confused with crossing over, in which an exchange of genetic material between homologous chromosome takes place. Translocation occurs as a result of interchange of chromosome segments in non-homologous cliromosomes.
There are three types:
1. Simple translocation
2. Shift translocation
3. Reciprocal translocation
i. Simple translocation : A single break is made in only one chromosome. The broken segment gets attached to one end of a non-homologous chromosome. It occurs very rarely in nature.
ii. Shift translocation : Broken segment of one chromosome gets inserted interstitially in a non-homologous chromosome.
iii. Reciprocal translocations : It involves mutual exchange of chromosomal segments between two non-homologous chromosomes. It is also called illegitimate crossing over.
It is further divided into two types.
a. Homozygous translocation: Both the chromosomes of two pairs are involved in translocation. Two homologous of each translocated chromosomes are identical.
b. Heterozygous translocation: Only one of the chromosome from each pair of two homologous are involved in translocation, while the remaining chromosome is normal. Translocations play a major role in the formation of species.
