Ingabe i-Genetics yokuguga isihluthulelo se-Cancer?
Wonke amangqamuzana anokuphila okuhleliwe okwenziwe ngawo, okwandisa, futhi ekugcineni abe ngaphansi kwe-apoptosis (ukufa kweseli) lapho engasasebenzi.
Ngokuvamile kusiza ukucabanga ngokuphindaphinda kwamaselula njengomshini we-photocopy endala: uma iselula ingakhophi ngokwayo, ngokungafani nakakhulu nokushintsha kabi isithombe. Ngokuhamba kwesikhathi, izakhi zofuzo zesisindo (i- DNA ) ziqala ukuphuka futhi iseli ngokwayo iba ikhophi ephaphathekile yendawo yokuqala.
Uma lokhu kwenzeka, ukufa okuhleliwe kweseli kuvumela iseli elisha ukuthatha futhi ligcine izinhlelo zisebenza.
Inombolo yezikhathi lapho iseli likwazi ukuhlukanisa liboshwe ngento eyaziwa ngokuthi umkhawulo weHayflick. Lokhu kuchaza isenzo lapho inqubo yokuhlukanisa (eyaziwa ngokuthi i-mitosis) ihlaziya kancane kancane izinto eziphilayo, ikakhulukazi ingxenye ye-DNA ebizwa ngokuthi i-telomere.
Umkhawulo weHayflick ubeka ukuthi iseli elijwayelekile lizohlukanisa phakathi kwezikhathi ezingu-50 kuya kwezi-70 ngaphambi kwe-apoptosis.
Ukuqonda i-Telomeres
I-Chromosomes izakhiwo ezinjengezintambo ezitholakala ngaphakathi kwe-nucleus yeseli. I-chromosome ngayinye yenziwe ngamaprotheni kanye ne-molecule eyodwa ye-DNA.
Ekupheleni komunye we-chromosome yi-telomere abantu abazovame ukuqhathaniswa namathiphu epulasitiki emaphethelweni e-shoelace. I-Telomeres ibalulekile ngoba ivimbela ama-chromosomes ukuba angavuli, anamathela komunye nomunye, noma ahlangane ngendandatho.
Njalo uma iseli lihlukanisa, i-DNA ephindwe kabili ihlukanisa ukuze ulwazi lwezofuzo lukopishwe.
Uma lokhu kwenzeka, i-DNA encoding iphindwe kabili kodwa hhayi i-telomere. Uma ikhophi isiphelile futhi i-mitosis iqala, indawo lapho iseli ihlanjululwe khona i-telomere.
Njengalokhu, ngesinye isizukulwane seseli, i-telomere iyancipha futhi ifushane kuze ingakwazi ukugcina ubuqotho be-chromosome.
Yilapho leyo apoptosis yenzeka.
I-Telomeres 'Ukuhlobene Nokuguga Nengculazi
Ososayensi bangasebenzisa ubude be-telomere ukuze banqume ubudala beseli nokuthi zingaki izimpendulo ezishiye. Njengoba ukuhlukaniswa kwamaseli kuhamba kancane, kufana nokuwohloka okuqhubekayo okubizwa ngokuthi i- senescence , esivame ukubhekisela ekugugeni . I-senescence yeselula ichaza ukuthi kungani izitho nezicubu zethu ziqala ukushintsha njengoba sikhula. Ekugcineni, wonke amangqamuzana ethu "abulalayo" futhi angaphansi kwe-senescence .
Konke, okungukuthi, kodwa okukodwa. Amaseli e-Cancer awukuphela kohlobo lweseli okungacatshangwa ukuthi "alufi." Ngokungafani namangqamuzana avamile, amangqamuzana omdlavuza awabheki ukufa komzimba kodwa angaqhubeka nokuphindaphinda ngaphandle kokuphela.
Lokhu, ngaphakathi kwayo, kuphazamisa ukulinganisela kokuphindaphinda kweselula emzimbeni. Uma uhlobo olulodwa lweseli luvunyelwe ukuphinda lungaphenduliwe, lungadlulisela bonke abanye futhi lulahleke imisebenzi esemqoka yezinto eziphilayo. Yilokho okwenzeka ngomdlavuza nokuthi kungani lezi "amangqamuzana" ezingenakufa zingabangela izifo nokufa.
Kukholelwa ukuthi umdlavuza uvela ngoba ukushintshashintsha kwezakhi zofuzo kungabangela ukukhiqizwa kwe-enzyme, eyaziwa njenge- telomerase , okuvimbela ama-telomere ukuba anciphise.
Ngenkathi yonke iseli emzimbeni inezinhlayiya zofuzo zokukhiqiza i-telomerase, amaseli athile kuphela ayidinga.
Amaseli wesidumbu, isibonelo, adinga ukuvala ukunciphisa i-telomere ukuze enze amakhophi angaphezu kwangu-50 ngokwabo; kungenjalo, ukukhulelwa angeke kwenzeke.
Uma ukuphazamiseka kwezakhi zofuzo kungahambisani nokukhiqiza kwe-telomerase, kungaholela amangqamuzana angavamile ukuba aphindise futhi enze ama-tumor. Kukholelwa ukuthi njengoba izinga lempilo yokuphila liqhubeka likhula, amathuba okuba akwenze angeke abe mkhulu kuphela kodwa ekugcineni angeke avinjelwe.
> Umthombo;
> Arai, Y .; UMartin-Ruiz, uC .; Takayama, M. et al. "Ukuvuvukala, kodwa akulona u-Telomere Ubude, Ubikezela Ukuguga Okuphumelelayo Ngesikhathi Esikhulile: Isifundo Se-Longitudinal Semi-supercentenarians." e BioMedicine . 2015; 2 (10): 1549-48; I-DOI: 10.1016 / j.ebiom.2015.07.029 ..