• Satellite DNA consists of highly repetitive DNA with very high frequency of adenine & thymine.
• Satellite DNA are of lower density hence when separated along with genomic DNA in a density gradient forms a  satellite Band.
• Its repeat length is several thousand Base pairs.
• Satellite DNA are organized as large clusters upto 100 million Base Pairs in the heterochromatic region of chromosomes near centromeres & telomeres, these are also found abundantly on Y chromosome
•  Satellite DNA shows exceptional variability among individuals particularly with regard to the number of repeats at a given locus hence is the basis of most DNA typing systems used in Forensic medicine.
• Satellite DNA are not transcribed into RNA
• Do not have spacer sequences
• Satellite DNA are located on 1, 9, 16 & Y chromosomes & tiny short arms of chromosomes 13-15 & 21-22.
• Satellite DNA base artificial chromosome ( SATACs) can be made by induced de novo chromosome formation in cells of different mammalian species. These artificially generated accessory chromosomes are composed of predictable DNA sequence and they contain defined genetic information. Prototype human SATACs have been successfully constructed in different cell types from neutral endogenous DNA sequence from the short arm of human chromosome 15.

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Types of Satellite DNA

• SIMPLE SEQUENCE REPEATS or Simple tandem repeats

  These are dispersed throughout the genome & forms the basis formodern tests that verify paternity, identity etc.

  These are of 2 types:

  • Minisatellites :- Base sequence of approximately 15-50 base pairs, repeated in tandem up to 1000times. There are approx 30,000 minisatellites loci in human genome.

  • Microsatellites :- < 15 bp, repeated 10=100 times, approx 200000 in human genome.

• Tandem repeats:- Located at telomeres & centromeres & may act as protein binding sites.

Satellite DNA especially microsatellites are thought to have originated by slippage of a replicated chromosome against its template. They are often found in transcription units. Often the base pair repetetion will disrupt proper protein synthesis leading to disease such as myotonic dystrophy.