Editing Palindrome (section)

=== Biological structures ===
{{Main|Palindromic sequence}}
[[File:DNA palindrome.svg|thumb|600px|right|Palindrome of [[DNA structure]]<br />A: Palindrome, B: Loop, C: Stem]]
Palindromic motifs are found in most [[genome]]s or sets of [[gene]]tic instructions. The meaning of palindrome in the context of genetics is slightly different, from the definition used for words and sentences. Since the [[DNA]] is formed by two paired strands of [[nucleotides]], and the nucleotides always pair in the same way ([[Adenine]] (A) with [[Thymine]] (T), [[Cytosine]] (C) with [[Guanine]] (G)), a (single-stranded) sequence of DNA is said to be a palindrome if it is equal to its complementary sequence read backward. For example, the sequence {{mono|ACCTAGGT}} is palindromic because its complement is {{mono|TGGATCCA}}, which is equal to the original sequence in reverse complement.

A palindromic [[DNA]] sequence may form a [[stem-loop|hairpin]]. Palindromic motifs are made by the order of the [[nucleotide]]s that specify the complex chemicals ([[protein]]s) that, as a result of those [[genetics|genetic]] instructions, the [[cell (biology)|cell]] is to produce. They have been specially researched in [[bacteria]]l chromosomes and in the so-called Bacterial Interspersed Mosaic Elements (BIMEs) scattered over them. In 2003, a research genome sequencing project discovered that many of the bases on the [[Y chromosome|Y-chromosome]] are arranged as palindromes.<ref>{{Cite web
 |url          = https://www.genome.gov/11007628/2003-release-mechanism-preserves-y-chromosome-gene/
 |title        = 2003 Release: Mechanism Preserves Y Chromosome Gene
 |website      = National Human Genome Research Institute (NHGRI)
 |language     = en-US
 |access-date  = 21 November 2017
 |archive-date = 1 December 2017
 |archive-url  = https://web.archive.org/web/20171201081105/https://www.genome.gov/11007628/2003-release-mechanism-preserves-y-chromosome-gene/
 |url-status   = live
}}</ref> A palindrome structure allows the Y-chromosome to repair itself by bending over at the middle if one side is damaged.

It is believed that palindromes are also found in proteins,<ref name="aac">{{cite journal
  | author  = Ohno S
  | title   = Intrinsic evolution of proteins. The role of peptidic palindromes
  | journal = [[Riv. Biol.]]
  | volume  = 83
  | issue   = 2–3
  | pages   = 287–91, 405–10
  | year    = 1990
  | pmid    = 2128128
}}</ref><ref name="ac">{{cite journal
 |doi          = 10.1023/A:1023454111924
 |vauthors     = Giel-Pietraszuk M, Hoffmann M, Dolecka S, Rychlewski J, Barciszewski J
 |title        = Palindromes in proteins
 |journal      = J. Protein Chem.
 |volume       = 22
 |issue        = 2
 |pages        = 109–13
 |date         = February 2003
 |pmid         = 12760415
 |s2cid        = 28294669
 |url          = http://www.kluweronline.com/art.pdf?issn=0277-8033&volume=22&page=109
 |access-date  = 2011-02-17
 |archive-date = 2019-12-14
 |archive-url  = https://web.archive.org/web/20191214234759/https://www.wolterskluwer.nl/
 |url-status   = dead
}}</ref> but their role in the protein function is not clearly known. It has  been suggested in 2008<ref name="am">{{cite journal |vauthors=Sheari A, Kargar M, Katanforoush A, etal |year=2008 |title=A tale of two symmetrical tails: structural and functional characteristics of palindromes in proteins |url= |journal=BMC Bioinformatics |volume=9 |page=274 |doi=10.1186/1471-2105-9-274 |pmc=2474621 |pmid=18547401 |doi-access=free }}</ref> that the prevalent existence of palindromes in peptides might be related to the prevalence of low-complexity regions in proteins, as palindromes frequently are associated with low-complexity sequences. Their prevalence might also be related to an [[alpha helical]] formation propensity of these sequences,<ref name="am" /> or in formation of protein/protein complexes.<ref name="X">{{cite journal
  | vauthors = Pinotsis N, Wilmanns M
  | title    = Protein assemblies with palindromic structure motifs
  | journal  = Cell. Mol. Life Sci.
  | volume   = 65
  | issue    = 19
  | pages    = 2953–6
  | date     = October 2008
  | pmid     = 18791850
  | doi      = 10.1007/s00018-008-8265-1
| s2cid = 29569626
 | pmc= 11131741
  }}</ref>