Single nucleotide polymorphism

A Single Nucleotide Polymorphism or SNP (pronounced snip) is a DNA sequence variation, occurring when a single nucleotide: adenine (A), thymine (T), cytosine (C) or guanine (G) - in the genome is altered. For example, a SNP might change the nucleotide sequence AAGCCTA to AAGCTTA. A variation must occur in at least 1% of the population to be considered a SNP.

Related Topics:
DNA sequence - Nucleotide - Adenine - Thymine - Cytosine - Guanine - Genome

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SNPs make up 90% of all human genetic variations, and occur every 100 to 300 bases along the human genome. Two of every three SNPs substitute cytosine (C) with thymine (T).

Related Topics:
Human - Bases - Human genome

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Variations in the DNA sequences of humans can affect how humans respond to diseases, bacteria, viruses, chemicals, drugs, etc.

Related Topics:
Disease - Bacteria - Virus - Chemical - Drug

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SNPs are of great value to biomedical research and in developing pharmacy products.

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Because SNPs do not change much from generation to generation, following them during population studies is straightforward. They are also used in some forms of genealogical DNA testing.

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SNPs are generally considered to be a form of point mutation that has been evolutionarily successful enough to recur in a significant proportion of a species' population.

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