Generation of Genetic variations

Genetic variation is an important part of evolutionary development:

There are three primary sources of genetic variations :

Mutations: Mutations are the changes in DNA. A single nucleotide change may cause effective changes in the species. Evolution involves several changes in the genetic make-up.

Sexual changes : Sex may introduce new variations in the community and can cause genetic variations.

Gene flow: When the flow of genes take place in between different populations. It results in genetic variations.

Single Nucleotide Polymorphism (SNP)

SNPs are one of the most common types of genetic variation. A Single Nucleotide Polymorphisms (also referred as SNPs) are the most commonly occurring genetic variations among the populations. They are the small genetic changes that occur within a person's DNA sequence when a single nucleotide, such as G is replaced by any of the three other bases A, C, or T. SNPs occur in both coding and non-coding region of the genome but majority of SNPs are found in the non-coding region and therefore, they do not exhibit any effect. SNPs found within a coding sequence may show silent, harmless, dormant or harmful effect. They are of particular interest because they are more likely to alter the biological function of a protein. The frequency of their occurrence varies from about 1 in 1000 bases to 1 in 100-300 bases. SNPs can help scientists to locate genes that are associated with specific diseases. SNPs play a vital role in disease development when they occur within a gene or in a regulatory region near a gene (Fig. 1; Table 1).

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DNA contains 99.9% of identical sequence in all the individuals with only 0.1% difference. Out of this 0.1% variation, over 80% are single nucleotide polymorphisms (SNPs).
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