What is a microsatellite?

The microsatellite is a short, recurring DNA sequence. Since they tend to change among closely related organisms, scientists often use microsatellites as genetic markers to identify individuals who come from the same breeding population. They are also known as short tandem repetitions (STRS) and simple sequential repetition (SSRS). Four nucleotides that appear in DNA are adenin (a), guanine (g), thymin (t) and cytosine (C). Adenin steam with thymin and pairs of guanine with cytosine. The order in which these couples of the base appear gives the DNA spring a unique signature and represents a code that stores genetic information. The following diagram of the short DNA spring shows the only GTC unit on the upper half and the CAG on the lower half, each repeated 4 times. Scientists would represent this as (GTC) _{4 or (CAG) 4 :}

        G T C G T C G G T C G T C
        | | | | | | | | | | | |
        C and G C A G C A G C AG
 
        
        
                      
                              
        
        
 These groups of recurring sequences have been named "microsatellites", because when DNA is separated by spinning in the centrifuge, it tends to group the large main zone surrounded by smaller "satellite" belts. Scientists have named DNA found in these bands Minisatelits and Microsatellites. Minisatites are longer segments that can consist of up to about 100 recurring pairs of bases. 

 Microsatellite markers are often useful for identifying individuals from the same breeding population. Mutation rarely occurs when the genetic sequence is passed on from parents to the child, resulting in several non -repetitive segment units. In our above example, (CAG)  4  state (CAG)  3  or (CAG)  5  could be (CAG). These mutations occur enough often that the population of wild breeding is likely to have different microsatellites than other breeding SKUPins, but there are rarely that individuals in one breeding group are likely to share certain characteristic sequences. 

 Most microsatellites are found in a non-coding DNA-DNA that does not have a "code" or instructions for the production of protein. As a result, they are not considered an important role in cell function. However, there is a reason to believe that the microsatellite can disrupt normal cellular processes if it grows too large. For example, in the case of Huntington's disease, the number of repetitions may mean a difference between disease disabilities or to be an unaffected carrier.