What is microsatellite?
A microsatellite is a short, repetitive sequence of DNA. Since they tend to vary little between closely related organisms, microsatellites are often used by scientists as genetic markers to identify individuals that come from the same breeding population. They are also known as short tandem repeats (STRs) and simple sequence repeats (SSRs).
If one thinks of a molecule of DNA as resembling a ladder, then each rung in the ladder is made up of a pair of smaller molecules called nucleotides. The four nucleotides that appear in DNA are adenine (A), guanine (G), thymine (T) and cytosine (C). Adenine pairs with thymine, and guanine pairs with cytosine. The order in which these base pairs appear gives a strand of DNA its unique signature and constitutes a code that stores genetic information.
A microsatellite occurs when a short sequence of base pairs, usually between 1
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These groups of repeating sequences were named "microsatellites" because, when DNA is separated by spinning it in a centrifuge, it tends to group into a large main band surrounded by smaller, "satellite" bands. Researchers named the DNA they found in these bands minisatellites and microsatellites. Minisatellites are longer segments, which may consist of up to about 100 repeating base pairs.
Microsatellites are useful markers at a wide range of scales of analysis. Until recently, they were the most important tool in mapping genomes -- such as the widely publicized mapping of the human genome. They serve a role in biomedical diagnosis as markers for certain disease conditions. That is, certain microsatellite alleles are associated (through genetic linkage) with certain mutations in coding regions of the DNA that can cause a variety of medical disorders. They have also become the primary marker for DNA testing in forensics (court) contexts -- both for human and wildlife cases (e.g., Evett and Weir, 1998). The reason