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Plasmagene is a term used to describe genetic elements that exist outside of the nucleus, typically within the cytoplasm of a cell.[1] These elements are usually associated with organelles like mitochondria and chloroplasts, which contain their own genetic material and replicate independently of the nuclear genome. Plasmagene theory as proposed by Tracy Sonneborn has significantly contributed to the understanding of non-Mendelian inheritance patterns, where traits are passed through cytoplasmic inheritance rather than through nuclear DNA.[2][3]
Function and characteristics
editPlasmagenes play crucial roles in various cellular processes, especially those involved in energy production. For instance, mitochondrial plasmagenes are integral to oxidative phosphorylation, the process responsible for generating most of the cell's ATP, the main energy currency of cells.[4] Though they can replicate independently, plasmagenes are often semi-autonomous, as they rely on nuclear genes for many essential proteins that support their functions.
Inheritance and implications
editOne of the most noteworthy aspects of plasmagenes is their involvement in non-Mendelian inheritance patterns. Unlike nuclear genes, which are inherited from both parents, plasmagenes are typically inherited maternally. This occurs because cytoplasmic organelles, like mitochondria, are transferred primarily through the egg cell during fertilization. Consequently, mutations or abnormalities in plasmagenes are linked to various inherited disorders, particularly those affecting muscular and neurological systems.[5]
Historical context and research
editResearch on plasmagenes dates back to the mid-20th century, focusing on their role in extranuclear inheritance and its implications for genetic diseases. These studies have been instrumental in elucidating how genetic information can be passed outside the nuclear DNA, altering the understanding of inheritance patterns and disease transmission.[6] The plasmagene theory was later disproved, and in 1976 Sonneborn affirmed this. But later researches after Sonneborn's death, provided validation allowing continued studies.[2]
References
edit- ^ "Plasmagene". Retrieved 17 October 2024.
- ^ a b Preer JR, Jr (March 2006). "Sonneborn and the cytoplasm". Genetics. 172 (3): 1373–7. doi:10.1093/genetics/172.3.1373. PMC 1456306. PMID 16554410.
- ^ Hayashi, J. (October 1991). "[Analysis of mitochondrial DNA as plasmagene]". Tanpakushitsu Kakusan Koso. Protein, Nucleic Acid, Enzyme. 36 (13): 2316–2319. ISSN 0039-9450. PMID 1745798.
- ^ Dippell, R. V. (1948). "Mutations of the killer plasmagene, kappa, in variety 4 of Paramecium aurelia". The American Naturalist. 82 (802): 43–50. doi:10.1086/281563. ISSN 0003-0147. PMID 18873203.
- ^ Darlington, C. D. (June 1948). "The plasmagene theory of the origin of cancer". British Journal of Cancer. 2 (2): 118–126. doi:10.1038/bjc.1948.17. ISSN 0007-0920. PMC 2007624. PMID 18098500.
- ^ Nevzgliadova, O. V. (1975). "[Nuclear suppression of a mitonchondrial mutation of tetracycline resistance in Saccharomyces cerevisiae]". Genetika. 11 (8): 108–114. ISSN 0016-6758. PMID 767211.