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== 2024.05.03 ==
=== Tetrahymena === As a ciliated [https://en.wikipedia.org/wiki/Protozoan protozoan], '''''Tetrahymena thermophila''''' exhibits [https://en.wikipedia.org/wiki/Nuclear_dimorphism nuclear dimorphism]: two types of cell [https://en.wikipedia.org/wiki/Cell_nucleus nuclei]. They have a bigger, [https://en.wikipedia.org/wiki/Somatic_cell non-germline] [https://en.wikipedia.org/wiki/Macronucleus macronucleus] and a small, [https://en.wikipedia.org/wiki/Germline germline] [https://en.wikipedia.org/wiki/Micronucleus micronucleus] in each cell at the same time and these two carry out different functions with distinct cytological and biological properties. This unique versatility allows scientists to use ''Tetrahymena'' to identify several key factors regarding [https://en.wikipedia.org/wiki/Gene_expression gene expression] and genome integrity. In addition, ''Tetrahymena'' possess hundreds of [https://en.wikipedia.org/wiki/Cilia cilia] and has complicated [https://en.wikipedia.org/wiki/Microtubule microtubule] structures, making it an optimal model to illustrate the diversity and functions of microtubule arrays. Because ''Tetrahymena'' can be grown in a large quantity in the laboratory with ease, it has been a great source for biochemical analysis for years, specifically for [https://en.wikipedia.org/wiki/Enzyme enzymatic] activities and purification of [https://en.wikipedia.org/wiki/Cell_(biology)#Subcellular_components sub-cellular components]. In addition, with the advancement of genetic techniques it has become an excellent model to study the gene function ''in vivo''. The recent sequencing of the macronucleus genome should ensure that ''Tetrahymena'' will be continuously used as a model system. ''Tetrahymena thermophila'' exists in 7 different sexes ([https://en.wikipedia.org/wiki/Mating_type mating types]) that can reproduce in 21 different combinations, and a single tetrahymena cannot reproduce sexually with itself. Each organism "decides" which sex it will become during mating, through a [https://en.wikipedia.org/wiki/Stochastic stochastic] process.<sup id="cite_ref-PLOS2013_5-0">[https://en.wikipedia.org/wiki/Tetrahymena#cite_note-PLOS2013-5 [5]]</sup><sup id="cite_ref-6">[https://en.wikipedia.org/wiki/Tetrahymena#cite_note-6 [6]]</sup> Studies on ''Tetrahymena'' have contributed to several scientific milestones including: #First cell which showed synchronized division, which led to the first insights into the existence of mechanisms which control the [https://en.wikipedia.org/wiki/Cell_cycle cell cycle].<sup id= "cite_ref-whitepaper_7-0">[https://en.wikipedia.org/wiki/Tetrahymena #cite_note-whitepaper-7 [7]]</sup> #Identification and purification of the first [https://en.wikipedia.org/wiki/Cytoskeleton cytoskeleton] based [https://en.wikipedia.org/wiki/Motor_protein motor protein] such as ''[https://en.wikipedia.org/wiki/Dynein dynein]''.<sup id="cite_ref-whitepaper_7-1">[https://en.wikipedia.org/wiki/Tetrahymena#cite_note-whitepaper-7 [7]]</sup> #Aid in the discovery of ''[https://en.wikipedia.org/wiki/Lysosomes lysosomes]'' and ''[https://en.wikipedia.org/wiki/Peroxisomes peroxisomes]''.<sup id="cite_ref-whitepaper_7-2">[https://en.wikipedia.org/wiki/Tetrahymena#cite_note-whitepaper-7 [7]]</sup> #Early molecular identification of somatic genome rearrangement.<sup id="cite_ref-whitepaper_7-3">[https://en.wikipedia.org/wiki/Tetrahymena#cite_note-whitepaper-7 [7]]</sup> #Discovery of the molecular structure of ''[https://en.wikipedia.org/wiki/Telomeres telomeres]'', ''[https://en.wikipedia.org/wiki/Telomerase telomerase]'' enzyme, the templating role of telomerase RNA and their roles in cellular senescence and chromosome healing (for which a Nobel Prize was won).<sup id="cite_ref-whitepaper_7-4">[https://en.wikipedia.org/wiki/Tetrahymena#cite_note-whitepaper-7 [7]]</sup> #Nobel Prize–winning co-discovery (1989, in Chemistry) of catalytic [https://en.wikipedia.org/wiki/RNA RNA] (''[https://en.wikipedia.org/wiki/Ribozymes ribozyme]'').<sup id="cite_ref-whitepaper_7-5">[https://en.wikipedia.org/wiki/Tetrahymena#cite_note-whitepaper-7 [7]]</sup><sup id="cite_ref-8">[https://en.wikipedia.org/wiki/Tetrahymena#cite_note-8 [8]]</sup> #Discovery of the function of [https://en.wikipedia.org/wiki/Histone histone] [https://en.wikipedia.org/wiki/Acetylation acetylation].<sup id="cite_ref-whitepaper_7-6">[https://en.wikipedia.org/wiki/Tetrahymena#cite_note-whitepaper-7 [7]]</sup> #Demonstration of the roles of [https://en.wikipedia.org/wiki/Posttranslational_modification posttranslational modification] such as acetylation and glycylation on [https://en.wikipedia.org/wiki/Tubulins tubulins] and discovery of the enzymes responsible for some of these modifications (glutamylation) #Crystal structure of 40S ribosome in complex with its initiation factor eIF1 #First demonstration that two of the "universal" [https://en.wikipedia.org/wiki/Stop_codon stop codons], UAA and UAG, will code for the amino acid [https://en.wikipedia.org/wiki/Glutamine glutamine] in some eukaryotes, leaving UGA as the only termination codon in these organisms.<sup id="cite_ref-9">[https://en.wikipedia.org/wiki/Tetrahymena#cite_note-9 [9]]</sup> <span style="font-size: 13.3333px;">link : [https://en.wikipedia.org/wiki/Tetrahymena https://en.wikipedia.org/wiki/Tetrahymena]</span><br/>
=== telomere ===