Satellite DNA


Satellite DNA

Satellite DNA consists of very large arrays of tandemly repeating, non-coding DNA. Satellite DNA is the main component of functional centromeres, and form the main structural constituent of heterochromatin.[1][2]

The name "satellite DNA" refers to how repetitions of a short DNA sequence tend to produce a different frequency of the nucleotides adenine, cytosine, guanine and thymine, and thus have a different density from bulk DNA - such that they form a second or 'satellite' band when genomic DNA is separated on a density gradient.[citation needed]

Contents

Types of satellite DNA

Satellite DNA, together with minisatellite and microsatellite DNA, constitute the tandem repeats.[citation needed]

Some types of satellite DNA in humans are:

Type Size of repeat unit (bp) Location
α (alphoid DNA) 171 All chromosomes
β 68 Centromeres of chromosomes 1, 9, 13, 14, 15, 21, 22 and Y
Satellite 1 25-48 Centromeres and other regions in heterochromatin of most chromosomes
Satellite 2 5 Most chromosomes
Satellite 3 5 Most chromosomes

Length

A repeated pattern can be between 1 base pair long (a mononucleotide repeat) to several thousand base pairs long, and the total size of a satellite DNA block can be several megabases without interruption. Most satellite DNA is localized to the telomeric or the centromeric region of the chromosome. The nucleotide sequence of the repeats is fairly well conserved across a species. However, variation in the length of the repeat is common. For example, minisatellite DNA is a short region (1-5kb) of 20-50 repeats. The difference in how many of the repeats is present in the region (length of the region) is the basis for DNA fingerprinting.[citation needed]

Origin

Satellite DNA, at least the microsatellite variety, is thought to have originated by slippage of a replicated chromosome against its template.[citation needed]

Pathology

Microsatellites are often found in transcription units. Often the base pair repetition will disrupt proper protein synthesis, leading to diseases such as myotonic dystrophy.[citation needed]

See also

References

  1. ^ Knight, Julian C. (2009). Human Genetic Diversity: Functional Consequences for Health and Disease. Oxford University Press. p. 167. ISBN 9780199227693. http://books.google.com/books?id=NSLeurRJWsIC&pg=PA167. 
  2. ^ "satellite DNA" at Dorland's Medical Dictionary

Further reading

External links


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Look at other dictionaries:

  • Satellite DNA — DNA that contains many tandem (not inverted) repeats of a short basic repeating unit. Satellite DNA is located at very specific spots in the genome (on chromosomes 1, 9, 16 and the Y chromosome, the tiny short arms of chromosomes 13 15 and 21 and …   Medical dictionary

  • satellite DNA — satellite DNA. См. сателлитная ДНК. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • satellite DNA — noun : a fraction of a eukaryotic organism s DNA that differs in density from most of its DNA as determined by centrifugation, that consists of short repetitive nucleotide sequences, that does not undergo transcription, and is often found in… …   Useful english dictionary

  • satellite DNA — noun Date: 1969 a fraction of a eukaryotic organism s DNA that differs in density from most of its DNA as determined by centrifugation, that consists of short repetitive nucleotide sequences, that does not undergo transcription, and that is often …   New Collegiate Dictionary

  • satellite DNA — (= minisatellite; microsatellite) DNA, usually containing highly repetitive sequences, that has a base composition (and thus density) sufficiently different from that of normal DNA that it sediments as a distinct band in caesium chloride density… …   Dictionary of molecular biology

  • satellite DNA — Highly repetitive DNA in plant and animal genomes, consisting of millions of copies of sequences typically in the range 5 500 bp long. Thousands of copies occur tandemly (head to tail) at each of many sites. It can be isolated from the rest of… …   Glossary of Biotechnology

  • satellite DNA —    Consists of many tandem repeats (identical or related) of a short basic repeating unit …   Forensic science glossary

  • alpha-satellite DNA — alpha satellite DNA. См. альфа сателлитная ДНК. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • cryptic satellite DNA — cryptic satellite DNA. См. криптическая сателлитная ДНК. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • heavy satellite DNA — heavy satellite DNA. См. тяжелая сателлитная ДНК. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.


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