Junk DNA

Junk DNA (non-functional DNA) is a DNA sequence that has no known biological function.[1][2] Most organisms have some junk DNA in their genomes—mostly, pseudogenes and fragments of transposons and viruses—but it is possible that some organisms have substantial amounts of junk DNA.[3]

All protein-coding regions are generally considered to be functional elements in genomes. Additionally, non-protein coding regions such as genes for ribosomal RNA and transfer RNA, regulatory sequences, origins of replication, centromeres, telomeres, and scaffold attachment regions are considered as functional elements. (See Non-coding DNA for more information.)

It is difficult to determine whether other regions of the genome are functional or nonfunctional. There is considerable controversy over which criteria should be used to identify function. Many scientists have an evolutionary view of the genome and they prefer criteria based on whether DNA sequences are preserved by natural selection.[4][5][6] Other scientists dispute this view or have different interpretations of the data.[7][8][9]

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  2. ^ Palazzo AF, Gregory TR (May 2014). "The case for junk DNA". PLOS Genetics. 10 (5): e1004351. doi:10.1371/journal.pgen.1004351. PMC 4014423. PMID 24809441.
  3. ^ Gil R, Latorre A (October 2012). "Factors behind junk DNA in bacteria". Genes. 3 (4): 634–650. doi:10.3390/genes3040634. PMC 3899985. PMID 24705080.
  4. ^ Ohno S (1972). "An argument for the genetic simplicity of man and other mammals". Journal of Human Evolution. 1 (6): 651–662. Bibcode:1972JHumE...1..651O. doi:10.1016/0047-2484(72)90011-5.
  5. ^ Morange M (2014). "Genome as a multipurpose structure built by evolution" (PDF). Perspectives in Biology and Medicine. 57 (1): 162–171. doi:10.1353/pbm.2014.0008. PMID 25345709. S2CID 27613442.
  6. ^ Palazzo AF, Kejiou NS (2022). "Non-Darwinian Molecular Biology". Frontiers in Genetics. 13: 831068. doi:10.3389/fgene.2022.831068. PMC 8888898. PMID 35251134.
  7. ^ Germain PL, Ratti E, and Boem F (2014). "Junk or functional DNA? ENCODE and the function controversy". Biology & Philosophy. 29 (6): 807–821. doi:10.1007/s10539-014-9441-3. S2CID 254277794.
  8. ^ Mattick JS (2023). "RNA out of the mist". Trends in Genetics. 39 (3): 187–207. doi:10.1016/j.tig.2022.11.001. PMID 36528415. S2CID 254768457.
  9. ^ Kellis M, Wold B, Snyder MP, Bernstein BE, Kundaje A, Marinov GK, et al. (April 2014). "Defining functional DNA elements in the human genome". Proceedings of the National Academy of Sciences of the United States of America. 111 (17): 6131–6138. Bibcode:2014PNAS..111.6131K. doi:10.1073/pnas.1318948111. PMC 4035993. PMID 24753594.