Mutation:
In a species, variations are caused by changes in the environment or any changes in the innate genetic setup of an organism or by the combination of both. Sudden change in the genetical set up of an organism is defined as mutation. In 1901, Hugo de Vries first used the term mutation based on his observation on Oenothera lamarckiana. Charles Darwin termed these sudden change as ‘sports’. According to Bateson, mutation is a discontinuous change. Based on molecular basis of heredity, mutation is defined as sudden change in the sequence of nucleotides of gene. The mutation brings about a change in the organism. The organism which undergoes mutation, is called a mutant. eg. Oenothera lamarckiana. Mutations that affect the biochemical reactions are called biochemical mutations. For example, biochemical mutants of Neurospora failed to synthesize certain amino acids. Some mutations drastically influence the
genes and cause death to the individual. Such mutation is described as lethal mutation. For example, in the plant Sorghum, recessive mutant fails to produce chlorophyll and therefore they die in the seedling stage. Thus, most of the mutations are harmful, because they disturb the genic balance of the organism. Although most of the mutations are useless and even harmful, and some of the mutations play a significant role in the evolution of new species. Many new strains of cultivated crops and new breeds of domesticated animals are the products of gene mutations. Small seeded Cicer arietinum (bengal gram) suddenly get mutated to large seeded Cicer gigas is the case of gene mutation.

Classification of mutation:
Mutations have been classified in various ways based on different criteria. Depending on the kind of cell in which mutations occur, they are classified into somatic and germinal mutation. They may be autosomal or sex chromosomal according to their type of chromosome in which they occur. They may be spontaneous or induced according to their mode of origin. They may be forward or backward according to their direction. They may be dominant or recessive according to their phenotypic expression of mutated genes.


Disclaimer
This channel does not promote or encourage any illegal activities.
All contents provided by this channel for general and education purpose only.
Copyright disclaimer under section 107 of the copyright act 1976,allowance is made for "fair use policy" for purposes such as criticism, comment, news reporting,teaching,scholarship and research. Fair use is a use permitted by copyright statute that might otherwise be infringing. Non-profit, educational or personal use tips the balance in favor of fair use.

свернуть