Genetic variation

Genetic variation refers to the difference in DNA among individuals.

There are multiple sources of genetic variation, including mutation and genetic recombination.

Genetic variation can be identified from observations of phenotypic variation in either quantitative traits or discrete traits coded for by one or a few genes, and by examining variation at the level of enzymes using the process of protein electrophoresis.

Polymorphic genes have more than one allele at each locus.

It is caused by variation in the order of bases in the nucleotides in genes.

DNA analysis has shown genetic variation in both coding regions and in the non-coding intron region of genes.

Genetic variation results in phenotypic variation, if variation in the order of nucleotides in the DNA sequence results in a difference in the order of amino acids in proteins coded by that DNA sequence.

If the resultant differences in amino acid sequence influence the shape, and thus the function of an enzyme.

Geographic variation means genetic differences in populations from different locations, and is caused by natural selection or genetic drift.

Within a population genetic variation commonly is measured as the percentage of gene loci that are polymorphic or the percentage of gene loci in individuals that are heterozygous.

Random mutations are the ultimate source of genetic variation.

Random mutations are rare and most mutations are neutral or deleterious.

In some instances random mutations can use new alleles that can be favored by natural selection.

Polyploidy is an example of chromosomal mutation, wherein organisms have three or more sets of genetic variation.

Genetic recombinations and random segregation during meiosis can result in new alleles or new combinations of alleles.

Random fertilization also contributes to variation.

Variation and recombination can be facilitated by transposable genetic elements, endogenous retroviruses, LINEs, SINEs, etc.

Genetic variation may be acquired in somatic cells or inherited through the germline.

Genetic variation can be divided into different forms according to the size and type of genomic variation.

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