Ngaba i-Genetics of Ageing Key to Cancer?
Zonke iiseli zineenkqubo zokuphila ezilungiselelwe zona, zanda, kwaye ekugqibeleni zithobela i-apoptosis (ukufa kweseli) xa zingasasebenzi.
Ngokuqhelekileyo kunceda sicinge ngokuphindaphinda kwamaselula njengomshini we-photocopy omdala: ngaphezulu iikopi zeefayili ngokwazo, ngakumbi ukugqithisa kwaye ukuphazamisa umfanekiso. Ngokuhamba kwexesha, izinto eziphathekayo zeeselini (i- DNA ) ziqala ukuphuka kwaye iseli ngokwayo iba yikhophi epholileyo yendalo.
Xa oku kwenzeka, ukufa kweselungisiwe kweseli kuvumela iseli elitsha ukuba lithathe kwaye ligcine iinkqubo ziqhuba.
Inani lamaxesha anesitya linokwahlula lubophelelwe ngumbono obizwa ngokuba ngumda weHayflick. Oku kuchaza isenzo apho inkqubo yokwahlula (eyaziwa ngokuba yi-mitosis) ihlaziya ngokunyanisekileyo i-genetic material, ngokukodwa inxalenye ye-DNA ebizwa ngokuba yi-telomere.
Umda weHayflick uchaza ukuba iseli ephakathi iya kwahlula phakathi kwama-50 ukuya kuma-70 maxesha ngaphambi kwe-apoptosis.
Ukuqonda iTelomeres
Ii- Chromosomes zizakhiwo ezinjenge-thread eziphakathi kwenyunithi yeseli. Nganye i-chromosome yenziwe ngeprotheni kunye neklasi enye ye-DNA.
Kwiphepha ngalinye le-chromosome yi-telomere apho abantu baya kuqhathaniswa nokuqhathaniswa neengcebiso zeplastiki kwiziphelo ze-shoelace. I-Telomeres ibalulekile kuba inqanda i-chromosomes ukuba ingabonakali, ibambelele komnye nomnye, okanye ifakwe kwisangqa.
Njalo ixesha i-cell ehlukana, i-DNA ephindwe kabini iyahlula ukuze ulwazi lwezofuzo lukopishwe.
Xa oko kwenzeka, i-DNA encoding iphindwe kabini kodwa ayikho i-telomere. Xa ikopi igqityiwe kwaye i-mitosis iqala, indawo apho iseli ihlanjululwe khona i-telomere.
Ngaloo ndlela, ngezizukulwana zeselula, i-telomere iya kufutshane kwaye imfutshane ibe ingakwazi ukugcina ingqibelelo ye-chromosome.
Yiloo nto i-apoptosis eyenzekayo.
I-Telomeres 'Ulwalamano nokuguga kunye neCanscer
Izazinzulu zingasebenzisa ubude be-telomere ukucacisa ubudala beeselingi kwaye zingaphi izimpendulo ezishiye. Njengoko ukwahlukana kwamaselula kuyancipha, kuqhutyelwa ukuhlakala okuqhubekayo okubizwa ngokuba yi- senescence , esiyibiza ngokuguga . I-celeslar sensescence ichaza ukuba kutheni amalungu ethu kunye nezicubu zethu ziqala ukutshintsha njengoko sikhula. Ekugqibeleni, zonke iiseli zethu "zifayo" kwaye zixhomekeke kwi-senescence .
Konke, oko kukuthi, kodwa enye. Iiseli zeentsholongwane zihlobo olulodwa lweselingo olunokuthi lucinge ukuba "alufi." Ngokungafani neeseli eziqhelekileyo, amangqamuzana omhlaza awafaki ukufa kweselungisiwe kodwa unokuqhubeka nokuphindaphinda ngaphandle kokuphela.
Oku, kwaye ngokwalo, kukuphazamisa ukulinganisela kokuphindaphinda kwamaselula emzimbeni. Ukuba uhlobo olunye lweseli luvunyelwe ukuphinda luphendule lungakhange lugqitywe, luyakunqumla bonke abanye kwaye luyichitha imisebenzi ebalulekileyo yezinto eziphilayo. Oku kwenzekayo nomhlaza kwaye kutheni le "i-immortal" iiseli zingabangela izifo nokufa.
Kukholelwa ukuba umdlavuza uvela kuba ukuguqulwa kwemfuyo kunokubangela ukuveliswa kwe-enzyme, eyaziwa ngokuba yi- telomerase , ekhusela i-telomeres ukuba ifinyeze.
Nangona yonke iseli emzimbeni inokubhala i-genetic coding ukuvelisa i-telomerase, iiseli ezithile kuphela ziyidinga.
Iiselingi zesitrosi, umzekelo, kufuneka ukutshintshwe i- telomere ukunciphisa ukwenzela ukwenza iikopi ezingaphezu kwama-50; Ngenye indlela, ukukhulelwa akunakwenzeka.
Ukuba ukuphazamiseka kwemfuyo kungaphenduli ngokuvelisa ukuveliswa kwe-telomerase, kungenza ukuba iiseli ezingaqhelekanga zande kwaye zenze izicubu. Kukholelwa ukuba njengoko izinga lokuphila kwexesha lokuphila liqhubeka likhula, amathuba okuba ayenzeki aya kuba mkhulu kuphela kodwa ekugqibeleni ayaba nako.
> Umthombo;
> Arai, Y .; UMartin-Ruiz, uC .; Takayama, M. et al. "Ukuvuvukala, kodwa akuyikho iTelomere Ubude, Uqikelela ukuguga ngokuphumelelayo kwixesha elide elide: Ufundiso olude lwamaSemi-supercentenarians." e BioMedicine . 2015; 2 (10): 1549-48; INGXELO: 10.1016 / j.ebiom.2015.07.029 ..