Satellite DNA | Minisatellite and Microsatellite | Short Tandem Repeats | Mol-bio

Satellite DNA is repetitive DNA consisting of short sequences repeated several times, forming arrays up to 100 megabase pairs. The repeat units vary in length from 150 to 400 base pairs and can be as short as three or four base pairs.

Satellite DNA, present in animals and plants, was first characterized through ultracentrifugation. It forms a small band at a lighter buoyant density compared to the main genomic DNA due to its lower GC content. Satellite DNA is highly repetitive with arrays of repeats and can be found in telomeres, centromeres, or interspersed throughout the chromosome.

Subtelomeric regions have a rapid mutation rate ranging from 10 to 100 base pairs. These repeat sequences, such as microsatellites, exhibit a very high mutation rate due to replication fork slippage. This phenomenon increases the chances of wrong base pairs during replication.

Repetitive DNA sequences, found in heterochromatinized structures like centromeres and pericentric regions, are not transcribed but have forensic significance due to the variation in tandem repeats between individuals. This polymorphism principle is used in forensic systems to identify suspects based on their chromosomal configurations and repetitive units.