Ukufuna Isakhi Sofuzo “Sokungafi”

IMIPHAKATHI eminingi inezindaba nezinganekwane ezizama ukuchaza ukufa kwesintu. Ngokwesibonelo, e-Afrika, enye inganekwane ithi uNkulunkulu wathuma unwabu wathi aluyotshela abantu ukuthi bangafi, kodwa lwahamba kancane kangangokuthi intulo, eyayithwele isigijimi sokufa, yafika kuqala. Isintu esikhohliseka kalula sabamba elentulo futhi salahlekelwa ukungafi.

Phakathi namakhulu eminyaka izazi zefilosofi nazo ziye zazama ukuphendula umbuzo othi, Kungani umuntu efa? Ekhulwini lesine B.C.E., isazi sefilosofi esingumGreki u-Aristotle safundisa ukuthi ukuqhubeka kwempilo yomuntu kuncike ekhonweni lomzimba lokukwazi ukulinganisela ukushisa nokubanda. Wathi: “Ukufa kubangelwa ukuntula ukushisa ngandlela-thile.” Ngakolunye uhlangothi, uPlato wafundisa ukuthi umuntu unomphefumulo ongafi osindayo ekufeni komzimba.

Namuhla, naphezu kwentuthuko emangalisayo yesayensi yanamuhla, imibuzo yezazi zezinto eziphilayo yokuthi kungani siguga futhi sifa, ayikaphendulwa nakancane. I-Guardian Weekly yaseLondon ithi: “Enye yezimfihlakalo ezinkulu zesayensi yezokwelapha akukhona ukuthi kungani abantu bebulawa izifo zenhliziyo nemithambo yegazi noma umdlavuza: kodwa ukuthi kungani befa ngisho noma bengaphethwe yilutho. Uma amangqamuzana omuntu ezihlukanisa, futhi eqhubeka ezivuselela ngokuzehlukanisa iminyaka engu-70 noma ngaphezulu, kungani evele eyeka esikhaleni nje ukuziphindaphinda?”

Ngenxa yokufuna ukuqonda inqubo yokuguga, izazi zesayensi yezakhi zofuzo nezesayenzi yamangqamuzana ziye zaphendukela ekucwaningeni ingqamuzana. Ososayensi abaningi banomuzwa wokuthi kulezi zinto ezincane kakhulu, kungatholakala isihluthulelo sokuphila isikhathi eside. Ngokwesibonelo, abanye babikezela ukuthi isayensi yokushintsha izakhi ngokushesha izovumela ososayensi ukuba banqobe umdlavuza nesifo senhliziyo. Kodwa isayensi isisondele kangakanani ekugcwaliseni isifiso somuntu sokuphila phakade?

Ukwembula Izimfihlakalo Zengqamuzana

Izizukulwane ezidlule zososayensi ziye zazama ukwembula izimfihlakalo zengqamuzana, kodwa zazingenawo amathuluzi adingekayo. Ososayensi baze bakwazi ukuhlola ngaphakathi kwengqamuzana futhi bathole ezinye zezici zalo eziyisisekelo kuleli khulu leminyaka elidlule kuphela. Baye batholani? Umbhali wesayensi uRick Gore uthi: “Siye sathola ukuthi ingqamuzana liyimbulunga yomhlaba encane.”

Ukuze ube nombono wokuthi ingqamuzana liyinkimbinkimbi kangakanani, cabangela ukuthi ngalinye linezigidi zezigidi zezingxenye ezincane ezibizwa ngokuthi ama-molecule. Nokho, lapho ososayensi bebona ukuma kwengqamuzana, bathola ukuhleleka okukhulu nobufakazi bokuthi laklanywa. UPhilip Hanawalt, ongumsizi kaprofesa wesayensi yezakhi zofuzo neyamangqamuzana eStanford University, uthi: “Ngisho nokukhula okuvamile kwengqamuzana eliphilayo elilula kudinga ukuba kube khona ukuguquka kwamakhemikhali ngendlela enokuxhumana.” Uphinde athi: “Izinto ezihleliwe eziye zafezwa yila mafektri amakhemikhali amancane zikudlula kude lokho okungase kwenziwe usosayensi endaweni yakhe yokucwaninga.”

Khona-ke ake ucabange nje ngomsebenzi oqeda amandla wokuzama ukwelula isikhathi sokuphila komuntu ngemizamo yesayensi. Ngeke nje udinge ulwazi olujulile ngezici eziyisisekelo zokwakheka kokuphila kodwa nekhono lokusebenzisa ngobuhlakani lezi zici! Ake sibheke kafushane ngaphakathi kwengqamuzana lomuntu ukuze sibonise izinselele ososayensi bezinto eziphilayo ababhekene nazo.

Konke Kusezakhini Zofuzo

Phakathi kwengqamuzana ngalinye kunesikhungo esiyinkimbinkimbi esilawula izinto esibizwa ngokuthi i-nucleus. I-nucleus iqondisa imisebenzi yengqamuzana ngokulandela uhlu lweziyalezo ezibekiwe. Lezi ziyalezo zigcinwa kuma-chromosome.

Ama-chromosome ethu ngokuyinhloko aneprotheni ne-deoxyribonucleic acid, noma i-DNA uma kunqanyulelwa.a Nakuba ososayensi baqala ukwazi nge-DNA kusukela ngasekupheleni kwawo-1860, baze baqala ngo-1953 ukuqonda ukwakheka kwama-molecule ayo. Ngisho nalapho, kwathatha cishe ishumi leminyaka ngaphambi kokuba izazi zezinto eziphilayo ziqale ukuqonda “ulimi” olusetshenziswa ngama-molecule e-DNA ekuthwaleni ukwaziswa kwezakhi zofuzo.—Bheka ibhokisi, ekhasini 22.

Ngawo-1930, izazi zezakhi zofuzo zathola ukuthi emaphethelweni e-chromosome ngayinye kukhona uchungechunge olufushane lwe-DNA esiza ukubamba i-chromosome. Njengoba zibizwa ngokuthi ama-telomere, kususelwa egameni lesiGreki elithi teʹlos (ekugcineni) nelithi meʹros (ingxenye), lezi zingxenyana ze-DNA zisebenza njengesivikelo esisekugcineni kwentambo yesicathulo. Ngaphandle kwama-telomere, ama-chromosome ethu abeyoqaqeka futhi agqashuke abe yizicucu, anamathelane noma angaqini.

Nokho, kamuva abacwaningi baphawula ukuthi kweziningi izinhlobo zamangqamuzana, ama-telomere aba mafushane ngemva kokuhlukana okulandelanayo kwengqamuzana. Ngakho-ke, ngemva kokuhlukana okungu-50 noma ngaphezulu, ama-telomere engqamuzana ancipha aba izigaxana ezincane, futhi ingqamuzana layeka ukuhlukana futhi ekugcineni lafa. Ukubona ukuthi amangqamuzana ayebonakala enesibalo esithile ahlukana agcine kuso ngaphambi kokuba afe kwaqala ukubikwa ngawo-1960 nguDkt. Leonard Hayflick. Ngakho-ke, lesi senzakalo ososayensi abaningi babhekisela kuso ngokuthi isibalo sikaHayflick.

Ingabe uDkt. Hayflick wasithola isihluthulelo sokuguga kwamangqamuzana? Abanye bacabanga kanjalo. Ngo-1975 i-Nature/Science Annual yathi ongqondongqondo abangamavulandlela omkhakha wokuguga bakholelwa ukuthi “zonke izidalwa eziphilayo ngaphakathi kuzo zinenqubo yokuzibhubhisa enesikhathi esiqondile, iwashi lokuguga eliqeda amandla okuphila.” Yebo, laqala ukulokoza ithemba lokuthi ekugcineni ososayensi base beqala ukugxila enqubweni yokuguga ngokwayo.

Ngawo-1990, abacwaningi abacwaninga amangqamuzana omdlavuza womuntu bathola omunye umkhondo obalulekile mayelana naleli “washi lamangqamuzana.” Bathola ukuthi amangqamuzana abulalayo ngandlela-thile akwazi ukuthola indlela yokunqoba “iwashi lamangqamuzana” nokuwenza angaqhubeki ehlukana phakade. Ukuthola lokhu kwaholela ososayensi bezinto eziphilayo emuva kuyi-enzyme engavamile neze, eyaqala ukutholwa ngawo-1980 futhi kamuva kwatholakala ukuthi ikhona ezinhlotsheni eziningi zamangqamuzana omdlavuza. Leyo enzyme ibizwa ngokuthi i-telomerase. Yenzani? Kalula nje, i-telomerase ingafaniswa nesihluthulelo esiqalisa phansi “iwashi” lengqamuzana ngokwandisa ama-telomere alo.

Ukuphela Kokuguga?

Ukucwaninga nge-telomerase kwasheshe kwaba omunye wemikhakha eshis’ izikhotha kuyisayensi yamangqamuzana. Kwaba sengathi uma ososayensi bezinto eziphilayo bengasebenzisa i-telomerase ukuze bavale ukuncipha kwe-telomere lapho amangqamuzana avamile ehlukana, mhlawumbe ukuguga kungase kuqedwe noma okungenani kubanjezelwe kakhulu. Ngokuthakazelisayo, i-Geron Corporation News ibika ukuthi abacwaningi abacwaninga nge-telomerase endaweni yokucwaninga kakade sebebonise ukuthi amangqamuzana omuntu avamile angase ashintshwe ukuze abe “nekhono elingapheli lokuziphindaphinda.”

Naphezu kwentuthuko engako, asikabi bikho isizathu sokukholelwa ukuthi maduze, ososayensi bezinto eziphilayo bazokwandisa kakhulu ukuphila kwethu nge-telomerase. Ngani? Ngenxa yokuthi ukuguga kuhilela okungaphezu nje kokuwohloka kwama-telomere. Ngokwesibonelo, cabangela lokho okwashiwo uDkt. Michael Fossel, umbhali wencwadi ethi Reversing Human Aging: “Uma sinqoba lokho esikwazi ngokuthi ukuguga namuhla, sisayoguga ngenye indlela entsha engajwayelekile. Uma siwandisa ama-telomere ethu ukuze angapheli, singase singabi nazo izifo esizihlobanisa nokuguga manje, kodwa ekugcineni siyowohloka futhi sife.”

Ngempela, cishe ziningi izici zokwakheka komuntu ezinengxenye enqubweni yokuguga. Kodwa okwamanje ososayensi abakakwazi ukuthola izimpendulo. ULeonard Guarente we-Massachusetts Institute of Technology uthi: “Okwamanje ukuguga kuseyimfihlakalo kakhulu.”—Scientific American, Fall 1999.

Nakuba ososayensi bezinto eziphilayo nabamangqamuzana ezakhi zofuzo beqhubeka behlolisisa ingqamuzana ukuze baqonde ukuthi kungani isintu siguga futhi sifa, iZwi likaNkulunkulu lembula isizathu sangempela. Limane lithi: “Ngomuntu oyedwa isono sangena ezweni nokufa kwangena ngesono, futhi kanjalo ukufa kwasakazekela kubantu bonke ngenxa yokuthi bonke bonile.” (Roma 5:12) Yebo, ukufa komuntu kuwumphumela wesimo isayensi engasoze yakwazi ukuselapha—isono esizuzwe njengefa.—1 Korinte 15:22.

Ngakolunye uhlangothi, uMdali uthembisa ukuqeda imiphumela yesono esizuzwe njengefa ngomhlatshelo wesihlengo kaKristu. (Roma 6:23) Singaqiniseka ukuthi uMdali wethu uyakwazi ukuqeda ukuguga nokufa, ngoba amaHubo 139:16 athi: “Amehlo akho angibona ngiseyihlule‚ zonke izinsuku zami zalotshwa encwadini yakho.” Ngokuqinisekile, uJehova uNkulunkulu wasungula isimiso sezakhi zofuzo futhi wasiloba phansi, ngomqondo ongokomfanekiso. Ngakho-ke, ngesikhathi sakhe esifanele, uyoqinisekisa ukuthi izakhi zethu zofuzo zivumela ukuphila okuphakade kulabo abalalela lokho akufunayo.—IHubo 37:29; IsAmbulo 21:3, 4.

[Umbhalo waphansi]

[Ibhokisi ekhasini 22]

“ULIMI” LWE-DNA

Izingxenye eziyisisekelo, noma “izinhlamvu” zolimi lwe-DNA yizici zamakhemikhali ezibizwa ngokuthi yizisekelo. Kunezinhlobo ezine zezisekelo: i-thymine, i-adenine, i-guanine ne-cytosine, ezivame ukufushaniswa ngokuthi T, A, G no-C. “Cabanga ngalezi zisekelo ezine njengezinhlamvu ohlwini lwezinhlamvu olunezinhlamvu ezine,” kusho umagazini i-National Geographic. “Njengoba sihlela izinhlamvu esinazo zenze igama elinengqondo, izakhi zethu zofuzo zakhiwa u-A, T, G no-C, abahlelwe ‘ngamagama’ anezinhlamvu ezintathu aqondwa isimiso sengqamuzana.” Bese kuthi lawo “magama” ezakhi zofuzo akhe “imisho” etshela ingqamuzana ukuthi liyenze kanjani iprotheni ethile. Uhlelo okuhlangana ngalo izinhlamvu ze-DNA yilo olunquma ukuthi iprotheni izosebenza njenge-enzyme ekusiza ukuba ugaye ukudla kwakho kwantambama, noma izoba isosha lomzimba elikuvikela emagciwaneni, noma izoba ngelinye lezinkulungwane zamaprotheni atholakala emzimbeni wakho. Yingakho nje incwadi ethi The Cell ibhekisela ku-DNA ngokuthi “ipulani eliyisisekelo sokuphila.”

[Isithombe ekhasini 21]

Amaphethelo ama-“chromosome” (aboniswe lapha ecwebezela) avumela amangqamuzana ukuba aqhubeke ehlukana

[Umthombo]

Courtesy of Geron Corporation