Wonke umuntu esifunda ngamangqamuzana ezinto eziphilayo, wokusebenza kwamakhemikhali ezintweni eziphilayo, ukushintshwa kwezakhi zofuzo nezinye izindawo eziningana lapho ulwazi oluhlobene nalokho, manje noma ngokuhamba kwesikhathi, ubuza umbuzo: uyini umsebenzi RNA polymerase? Lena sihloko eyinkimbinkimbi ukuthi namanje nhlobo nhlobo, kodwa, nokho, ukuthi uzobe ovuthayo njengengxenye sihloko yaziwa.
ulwazi olujwayelekile
Kuyadingeka ukuba ukhumbule ukuthi kukhona i-RNA polymerase ka eukaryotes futhi prokaryotes. Esokuqala okwengeziwe ihlukaniswe ezintathu izinhlobo, ngamunye okuyinto obangela umbhalo zezakhi zofuzo iqembu ahlukene. Lezi enzyme zibaliwe ukuze kube lula, njengoba kuqala, okwesibili nokwesithathu RNA polymerase. Prokaryotes, isakhiwo zazo ze-non-zenuzi, lapho eloba usebenza ngokuvumelana umdwebo lula. Ngakho-ke, ukuzwakala, ukuze uthwebule ulwazi oluningi ngendlela eukaryotes kungenzeka kuzothathwa. RNA polymerases kukhona ikhipha efanayo. Kukholakala ukuthi ziqukethe ezingengaphansi kwezingama-10 polypeptide ngamaketanga. Ngakho-RNA polymerase synthesizes 1 (transcribes) izakhi zofuzo zazo kamuva lahunyushelwa namaprotheni ahlukahlukene. Eyesibili wahlanganyela izakhi zofuzo ukuguqulela, okuyinto kamuva lahunyushelwa amaprotheni. RNA polymerase 3 ubonisa ahlukahlukene esitebeleni ongaphakeme yamangqamuzana isisindo enzyme ukuthi ngokulinganisela ebucayi-alpha amatinu ukuphi. Kodwa asizange lunqunywe ncamashi yilokhu RNA polymerase! Ngakho ngokuthi enzyme ukuthi bekwi synthesis ribonucleic acid molecule. Ngomqondo ewumngcingo kuqondwe le-DNA ancike RNA polymerase, letisebenta ngesisekelo matrix of deoxyribonucleic acid. Enzyme kubalulekile ukuze uphile ukusebenza eside futhi yimpumelelo yezinto eziphilayo. RNA polymerase kungatholakala wonke amaseli namagciwane amaningi.
Lesi sigaba ku imininingwane
Kuye Ukwakheka subunit RNA polymerases zihlukaniswe amaqembu amabili:
- Amadili kuqala nge ukuguqulela inombolo encane zofuzo genomes of elula. Ngokuba ukusebenza kuleli cala akudingi umthelela zokulawula eziyinkimbinkimbi. Ngakho-ke, lapha libhekisela kubo bonke enzyme aqukethe subunit eyodwa kuphela. Njengoba isibonelo Ingabangela le bacteriophage RNA polymerase futhi mitochondria.
- Leli qembu kuhlanganisa wonke eukaryotic RNA polymerase namagciwane, okuyinto okunzima wahlela. Ziyakwazi eyinkimbinkimbi mnogosubedinichnye amaprotheni izakhiwo ezingaba ukubhala ezinkulungwane zezakhi zofuzo ezahlukene. Ngesikhathi kokuhlinzwa, lezi izakhi zofuzo aphendule inqwaba amasignali zokulawula atholakale kusuka amaprotheni izici futhi ama-nucleotide.
division okunjalo kwesakhiwo obusebenzayo kunalokho okunemibandela kanye yokuncishiswa isimo sangempela.
Lisho ukuthini-RNA polymerase mina?
Bakhandwa fixed umsebenzi imfundo ka imibhalo eyinhloko rRNA ufuzo, okungukuthi, yizo ezibaluleke kakhulu. Laba kabanzi eyaziwa ngaphansi ekubizweni 45S-RNA. Ubude yabo imayelana 13 000 ama-nucleotide. Kusukela ke akhiwa-28-i-RNA, 18S-5.8S RNA-RNA. Ngenxa yokuthi ziyadalwa transkriptor eyodwa kuphela, umzimba ithola "isiqinisekiso" ukuthi amangqamuzana kuyokwenziwa kwakheka amanani alinganayo. Ngesikhathi esifanayo ukudalwa RNA samaqanda nucleotide 7000 kuphela. Ezinye izindaba zika-okulotshiweyo is phansi nucleus. Ku-zinsalela ezinkulu ezifana Kunenkolelo ukuthi kubalulekile ukuba kusaqalwa kumiswa ribosomes. Isibalo sazo polymerases kumaseli yezidalwa ephakeme endiza eduze uphawu amayunithi ayizinkulungwane 40.
Indlela ehlelwe ngayo?
Ngakho, siba RNA polymerase lokuqala (prokaryotes-isakhiwo molecule) kubhekwa okuhle. Kulokhu, lo subunit ezinkulu, njengoba ngempela futhi inani elikhulu nezinye eliphezulu yamangqamuzana isisindo polypeptides, kusobala ukuthi kukhona izizinda akachazeki tekusebentisa kwesakhiwo. Phakathi cloning zezakhi zofuzo futhi ukunquma isakhiwo yabo eyinhloko sezihlonziwe ososayensi evolutionarily izingxenye alondolozwe ngamaketanga. Ukusebenzisa inkulumo enhle, abacwaningi abangu bawenza ukuhlaziywa mutational evumela ukuba sikhulume thazeka obusebenzayo lwezizinda ngabanye. Ngenxa yale njongo, usebenzisa mutagenesis indawo eziqondiswe ukushintsha umuntu polypeptide ngamaketanga, ezifana acid Ushintshe acid subunits elisetshenziswa inhlangano yama-enzymes ne ukuhlaziywa okwalandela izakhiwo, okuyinto eyatholakala ku izakhiwo idatha. Kwaphawulwa ukuthi ngenxa inhlangano yayo ye-RNA polymerase kuqala khona-alpha-amatina (ikhemikhali enobuthi kakhulu, okuyinto etholakala toadstool okhanyayo) akasabeli.
ukusebenza
Kokubili lokuqala kanti eyesibili RNA polymerase kungenzeka akhona amafomu amabili. Omunye wabo kungaba isinyathelo Ukuqala umbhalo othize. Esesibili - a DNA ancike RNA polymerase. Lesi simo sengqondo kubonakala ukusebenza elikhulu umsebenzi. Isihloko wafunda okuningi, kodwa manje siyazi ukuthi kuxhomeke ezicini ezimbili umbhalo, okubhekiselwe kuyo njengoba SL1 futhi UBF. Ikakhulukazi lesi samuva - ukuthi akwazi ukuxhumana ngokuqondile umgqugquzeli, kuyilapho SL1 UBF kudinga khona. Nakuba liye Ucwaningo luthole ukuthi DNA ancike RNA polymerase iqhaza umbhalo okungenani kanye ngaphandle kobukhona lakamuva. Kodwa ukusebenza evamile lamasu UBF sisadingeka. Kungani becabanga kanjalo? kuze kube manje Kuyaphawuleka kuhlulekile ukuze kutholakale imbangela yalokhu kuziphatha. Enye incazelo ethandwa kakhulu kusikisela ukuthi UBF khulumela uhlobo ivuselela rDNA umbhalo lapho utshala futhi eba. Lapho uhlezi isigaba kwenzeka, khona-ke zigcinwe okuyisilinganiso esiphansi semali edingekayo ezingeni ukusebenza. Ingxenye umbhalo izici akuxhomekile ngaye. Lapha ngakho isebenza RNA polymerase. Inhloso yalolu enzyme ivumela ukusekela ukudlalwa encane "amabhlogo wokwakha" yomzimba, ngenxa ngalo njalo olusha amashumi eminyaka.
Iqembu lesibili enzyme
ukusebenza kwawo kulawulwa inhlangano yabantwana bakwa multiprotein eziyinkimbinkimbi preinitsiatornogo abagqugquzeli balo nekilasi lesibili. Ngokuvamile lokhu sivezwe kula umsebenzi namaprotheni ekhethekile - activators. Njengoba isibonelo i-TBP. It is ezihambisana izici eziyingxenye TFIID. Bona - ilitshe ngoba p53, NF kappa B, nokunye. Ithonya inqubo isiqondiso sayo futhi unikeze amaprotheni abizwa ngokuthi ama coactivators. Izibonelo kukhona Gcn5. Kungani sidinga lezi amaprotheni? Bakhonza njengabashumayeli adapters ukuthi ngezifiso nokuxhumana activators kanye izici ukuthi kukhona eziyinkimbinkimbi preinitsiatorny. Ukuze kulungiswe umbhalo iphutha, kumele ube ezidingekayo umqalisi izici. Naphezu kweqiniso lokuthi nesithupha kuwo, ngqo uxhumana umgqugquzeli kungenzeka kuphela. Ukuze uthole ezinye izimo kudinga eziyinkimbinkimbi preformed yomzuzwana RNA polymerase. Ngaphezu kwalokho, phakathi nalezi zinqubo eduze proximal izakhi - ngazimbili kusuka kusayithi lapho umbhalo ithoma 50-200 kuphela. Ziqukethe inkomba yokubopha Activator amaprotheni.
izici ezithile
Ingabe isakhiwo subunit we enzyme Lokudabuka ezahlukene ngendima yabo emikhakheni umbhalo? Impendulo ngqo kule mibuzo ingucha kodwa wayekholelwa ukuthi kungenzeka omuhle. Kwenzeka kanjani ukuba ithinta RNA polymerase? imisebenzi enzyme isakhiwo esilula - ibanga elilinganiselwe umbhalo zezakhi zofuzo (noma ingxenye encane). Izibonelo synthesis RNA kwenziwa Okazaki izinsalela. I ngokucacile umgqugquzeli we polymerases RNA amagciwane athile kanye phages wukuthi enzyme kukhona abanikazi isakhiwo elula zahlukahlukene. Lokhu kungabonakala inqubo ye-DNA ukufanisana e amagciwane. Nakuba singeke sikwazi ake ucabangele lokhu: isakhiwo eziyinkimbinkimbi lapho wafunda ufuzo T ngisho phage, phakathi ukuthuthukiswa, yaphawula ukuthi okuphindaphindiwe ushintsha phakathi kwamaqembu ahlukahlukene isakhi sofuzo umbhalo, kwatholakala ukuthi eziyinkimbinkimbi ukusetshenziselwa lokhu aphethe RNA polymerase. Okungukuthi, iprotheni elula ezimweni ezinjalo ngeke eyenga. Lokhu kusho eziningana imiphumela:
- RNA polymerase ka eukaryotes namagciwane kumele bakwazi ukuqaphela abagqugquzeli ezahlukene.
- Kuyadingeka ukuthi enzyme has impendulo eqondile ukuze ezahlukene amaprotheni-nabalawuli.
- RNA polymerase kumelwe futhi bakwazi ukushintsha ukuqashelwa ngokucacile isifanekiso DNA nucleotide ukulandelana. Ukuze wenze lokhu, sebenzisa ezihlukahlukene amaprotheni effectors.
Ngakho isidingo samanzi emzimbeni ukuze "isakhiwo" izakhi ezengeziwe. Amaphrotheni ukusiza ukubhala eyinkimbinkimbi RNA polymerase ukuze ngokugcwele ukufeza imisebenzi yayo. Lokhu kusebenza, ngoba iningi labo, uketshezi isakhiwo eziyinkimbinkimbi, lapho amathuba ekusebenziseni uhlelo olubanzi ukwaziswa kwezakhi zofuzo. Ngenxa yezinkinga ezihlukahlukene, singakwazi ukugcina uhlobo isakhiwo isigaba sabaphathi RNA polymerase.
Kanjani inqubo umbhalo?
Ingabe ikhona isakhi sofuzo esiyimbangela yalesi wokulala ne polymerase RNA? Ukuqala of umbhalo: inqubo e eukaryotes senzeka nucleus. Ngo prokaryotes, ngulona logeleta ngaphakathi lesi silwanyana. Ubudlelwane phakathi polymerase kuyinto isimiso esiyisisekelo isakhi a ayahambelana kokuzalela ngabanye molecule. On izimpikiswano nokuxhumana ongathi DNA nje isifanekiso futhi akashintshi phakathi umbhalo. Njengoba i-DNA ithi enzyme lephelele, into eqinisekile, ukuthi kwatholakala ukuthi isakhi sofuzo esithile uyena owenza lokhu polymer kungaba, kodwa kuyoba isikhathi eside kakhulu. Akufanele sibakhohlwe ukuthi DNA iqukethe 3.1 bhiliyoni izinsalela nucleotide. Ngakho-ke, kuhle kakhulu ukuba bathi for uhlobo RNA ngalinye liyahlangana DNA yayo. Ukuze ukugeleza ukusabela polymerase idinga amandla futhi ribonukle-ozidtrifosfato substrates. Uma kukhona akhiwa 3 ', 5'-phosphodiester isibopho phakathi ribonukleozidmonofosfatami. Mpilo RNA zamagama iqala ukulandelana ezithile DNA (abagqugquzeli). Inqubo evala at ekunqanyulweni amasayithi (ekunqanyulweni). Isayithi, okuyinto ehilelekile lapha kubizwa ngokuthi transcriptional. Ngo eukaryotes, kukhona ngokuvamile isakhi sofuzo esisodwa kuphela, kuyilapho prokaryotes Ungase futhi ifa izingcezu amaningi yekhodi. transcriptional ngayinye inemisebenzi uninformative. Basuke etholakala nucleotide inqubo ethile ukuthi basebenzisane izici transcriptional zokulawula eshiwo ngenhla.
Amagcikwane RNA polymerase
Lezi nezilwanyana ezincane omunye enzyme unesibopho synthesis mRNA, rRNA futhi tRNA. Isilinganiso polymerase-molecule has a cishe 5 subunits. Amabili kula ma-ukukhonza njengephayona esibophezelayo amalungu enzyme. Enye subunit abathintekayo emizameni yokuthuthukisa zamagama. Kukhona ingxenye enzyme nonspecific ngokuxhumana nge-DNA. Futhi subunit sokugcina beletha polymerase RNA ifomu zokusebenza. Kuyaphawuleka ukuthi amangqamuzana enzyme ungekho "khulula" ukuzulazula kule cytoplasm kwamagciwane. Lapho zisetshenziswa RNA polymerases ke babopha izifunda ze-non-ethize DNA futhi balinde kuze umgqugquzeli asebenzayo ivulekile. Nasi thikazisa isihloko, kufanele kusho ukuthi amagciwane esivumelana kakhulu ukufunda amaprotheni ithonya labo phezu ribonucleic acid polymerase. elula kakhulu ukuba asebenzise ukushukuma nobe okusithiyayo izici ngamunye. Ngenxa okusezingeni eliphezulu ukukhiqizwa kabusha isilinganiso sabo kungaba kuqhathaniswa ngokushesha uthole yi oyifunayo. Maye, isifundo babantu abakwazi kwenziwe ngesikhathi okusheshayo ijubane sibonga enjalo ukwahlukana kwethu kwesakhiwo.
RNA polymerase "babanjwa" ngezindlela ezihlukahlukene?
Lokho kuziwa esiphethweni esinengqondo isihloko. Ukunakwa main sakhokhwa eukaryotes. Kodwa kusekhona archaea nama-virus. Ngakho ofuna ukukhokha kancane ukunakwa lezi zinhlobo zokuphila. Umsebenzi esibalulekile Archean kukhona kuphela iqembu elilodwa-RNA polymerases. Kodwa kufana kakhulu impahla yayo kanye izinhlangano eukaryotes ezintathu. Ososayensi abaningi baye basikisela ukuthi esingakubona kusukela Arche empeleni ukhokho yokuziphendukela kwemvelo polymerases ezikhethekile. Kuyathakazelisa futhi isakhiwo amagciwane. Njengoba nje kulotshiwe ngaphambili, akuwona wonke la magciwane kufanele polymerase yabo. Futhi ikuphi, kuba subunit olulodwa. Kukholakala ukuthi enzyme viral ethathwe polymerases DNA, esikhundleni eziyinkimbinkimbi RNA izakhiwo. Nakuba ngenxa ukuhlukahluka leli qembu nezilwanyana ezincane ukuqaliswa ezahlukene ihlangabezana indlela inikezwe begazi.
isiphetho
Maye, isintu akusho okwamanje Imininingwane vsoy kudingekile kudingeka ukuqonda ufuzo. Futhi lokho kuphela ayengenza! Cishe zonke izifo ngokuyisisekelo nje isisekelo zofuzo - lokhu kusebenza ikakhulukazi ukuba emagciwaneni njalo usinika izinkinga yizifo nokunye. I eziyinkimbinkimbi kakhulu futhi ezingelapheki izifo - kunjalo futhi, eqinisweni, kuncike ngokuqondile noma ngokungaqondile ku zofuzo lomuntu. Lapho sifunda ukuqonda ngokwazo futhi sizosebenza lolu lwazi ukuze kusizakale inqwaba izinkinga nezifo uyomane esabakho. Manje into yesikhathi esidlule, izifo eziningi ngaphambili ezimbi ezifana ingxibongo, isifo. Ngilungela ukuya mumps, ukukhwehlela whooping. Kodwa musa uphumule, ngoba sibhekene inombolo enkulu nakakhulu nezinselelo ezahlukene ukuthi udinga ukuthola impendulo. Futhi kuyotholakala, ngoba kuzoba ukwenza kanjalo.