Direct repeat

Direct repeats are a type of genetic sequence that consists of two or more repeats of a specific sequence. In other words, the direct repeats are nucleotide sequences present in multiple copies in the genome. Generally, a direct repeat occurs when a sequence is repeated with the same pattern downstream. There is no inversion[clarification needed] and no reverse complement associated with a direct repeat. It may or may not have intervening nucleotides. The nucleotide sequence written in bold characters signifies the repeated sequence.

5´ TTACGnnnnnnTTACG 3´
3´ AATGCnnnnnnAATGC 5´

Linguistically, a typical direct repeat is comparable to saying "bye-bye".

Types

There are several types of repeated sequences:

Microsatellite DNA

A tract of repetitive DNA in which a motif of a few base pairs is tandemly repeated numerous times (e.g. 5 to 50 times) is referred to as microsatellite DNA. Thus direct repeat tandem sequences are a form of microsattelite DNA. The process of DNA mismatch repair plays a prominent role in the formation of direct trinucleotide repeat expansions. Such repeat expansions underlie several neurological and developmental disorders in humans.

Homologous recombination

In directly repeated sequences of the tobacco plant genome, DNA double-strand breaks can be efficiently repaired by homologous recombination between the repeated sequences.

See also

References

  1. 1 2 3 Ussery, David W.; Wassenaar, Trudy; Borini, Stefano (2009). "Word Frequencies and Repeats §Word Frequencies, Repeats, and Repeat-related Structures in Bacterial Genomes". Computing for Comparative Microbial Genomics: Bioinformatics for Microbiologists. Computational Biology. Vol. 8 (1 ed.). Springer. pp. 133–144. doi:10.1007/978-1-84800-255-5_8. ISBN 978-1-84800-254-8.
  2. ↑ "Repetitive Sequences, Nucleic Acid". Medical Subject Headings (MeSH). U.S. National Library of Medicine. Retrieved 5 October 2026.
  3. 1 2 Richard, G. F. (2021). "The Startling Role of Mismatch Repair in Trinucleotide Repeat Expansions". Cells. 10 (5): 1019. doi:10.3390/cells10051019. PMC 8145212. PMID 33925919.
  4. ↑ Siebert R, Puchta H (May 2002). "Efficient repair of genomic double-strand breaks by homologous recombination between directly repeated sequences in the plant genome". Plant Cell. 14 (5): 1121–31. doi:10.1105/tpc.001727. PMC 150611. PMID 12034901.