• A mutation is a change in the amount, arrangement or structure of DNA of an organism. This produces a change in genotype which may be inherited by cells derived by mitosis or meiosis from the mutated cell. A mutation may results in the change in appearance of a characteristics in a population.
• Mutation occurring in a gamete are inherited in offspring, whereas those occurring in somatic cells can only be inherited by daughter cells produced by mitosis. Therefore, mutation can be germ-line and somatic.
• A mutation resulting from a change in the amount or arrangement of DNA or chromosome is known as chromosomal mutation or chromosomal aberration whereas mutation of DNA at a single locus is termed as gene mutation or point mutation
• Mutation involving either entire chromosome or large portions of chromosome are referred as chromosomal mutation. Such mutation in chromosome is caused by either by inheritance of extra fragment/whole chromosome or loss of fragment/whole chromosome or by rearrangement of genes.

Types of chromosomal mutation:

There are two categories of chromosomal mutation

1. Chromosomal aberration:
   • The chromosomal mutation that involves changes in gross morphology or architecture of chromosome known as chromosomal aberration.
   • This is the structural abnormality of chromosome.
   • The chromosome generally remains unchanged but during certain condition leading to mutation causes certain changes in structure of chromosome which may result in loss or gain of genes or rearrangement of position of genes.
   • Variation in chromosomal structure are due to- deletion, duplication, translocation and inversion
2. Numerical aberration of chromosome:
   • The chromosomal mutation which result from the change in number of chromosome known as numerical aberration of chromosome.
   • This is the phenomenon of ploidy

Chromosomal mutation-chromosomal aberration (structural mutation) and genomatic mutation (numerical aberration)

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