Duk wanda ke karanta ilmin sanin kwayoyin halittu, Biochemistry, a kayyade aikin injiniya, da kuma da dama sauran related ilimi, jima ko daga baya, ya tambaye ta tambaya: mene ne aikin da RNA polymerase? Wannan shi ne wani fairly hadaddun topic cewa shi ne har yanzu gaba daya unexplored, amma, duk da haka, an san cewa shi za a lit matsayin wani ɓangare na labarin.
janar bayanai
Wajibi ne a tuna da cewa akwai RNA polymerase na eukaryotes da prokaryotes. Na farko shi ne kara kasu iri uku, kowanne daga abin da yake da alhakin kwafi na genes raba rukuni. Wadannan enzymes aka ƙidaya for sauki, kamar yadda na farko, na biyu da na uku RNA polymerase. Prokaryotes, tsarin na wanda ba makaman nukiliya, a lokacin da rubuce aiki bisa ga Sauki zane. Saboda haka, domin tsabta, kama kamar yadda bayani da yawa za a bi eukaryotes. RNA polymerases suna da fasali irin wannan. An yi imani da cewa suna dauke da ba kasa da 10 polypeptide sarƙoƙi. Kamar wancan RNA polymerase synthesizes 1 (transcribes) genes wanda ake baya fassara a cikin daban-daban sunadarai. Na biyu tsunduma sauya rubũtun tamkar kwayoyin halitta, wanda ake baya fassara a cikin sunadaran. RNA polymerase 3 nuna daban-daban barga low kwayoyin nauyi enzymes cewa ne moderately m ga alpha amatinu. Amma mu ba su yanke shawarar a kan abin da daidai ne RNA polymerase! Don haka ya kira enzymes cewa suna tsunduma a cikin kira na ribonucleic acid kwayoyin. A cikin kunkuntar ji gane da wannan DNA-RNA dogara polymerase, wanda aiki a kan tushen da matrix na deoxyribonucleic acid. Enzymes suke da muhimmanci ga mai tsawo da kuma nasara aiki na rayayyun kwayoyin halitta. RNA polymerase za a iya samu a duk Kwayoyin da yawa ƙwayoyin cuta.
A rabo a kan ƙayyadaddu
Dangane da subunit abun da ke ciki na RNA polymerases ya kasu kashi biyu kungiyoyin:
- A farko da alaka da sauya rubũtun tamkar wani karamin yawan kwayoyin halittu a cikin kwayoyin na qwarai. Domin da aiki a cikin wannan hali ba ya bukatar hadaddun kullum tasiri. Saboda haka, a nan tana nufin duk enzymes cewa kunshi daya kawai subunit. Kamar yadda wani misali iya sa da bacteriophage RNA polymerase da mitochondria.
- Wannan kungiya ta hada dukkan eukaryotic RNA polymerase da kwayoyin cuta, waxanda suke da wuyar shirya. Su ne m mnogosubedinichnye gina jiki gidaje da cewa zai iya rubũtunsa dubban daban-daban kwayoyin halittu. Lokacin aiki, wadannan genes amsa ga wani babban yawan dokokin da siginar da aka samu daga furotin dalilai da nucleotides.
Irin wannan tsarin da kuma aikin rabo ne wajen matukar da wani simplification na real halin da ake ciki.
Menene RNA polymerase na?
Suna tsayayyen aiki na ilimi na farko tarihi na rRNA da kwayoyin halittu, wato, su ne mafi muhimmanci. A karshen an fi sani a karkashin nadi na 45S-RNA. Su tsawon shi ne game da 13 000 nucleotides. Daga shi an kafa 28S-RNA, 18S-5.8S RNA-RNA. Saboda gaskiya cewa aka halitta su daya kawai transkriptor, jiki sami wani "garanti" cewa kwayoyin za a kafa a daidai yawa. A lokaci guda halittar RNA kai tsaye da ke kawai 7000 nucleotides. Sauran kwafi aka kaskanta a tsakiya. A irin wannan babban saura yi imani da cewa wajibi ne ga farkon matakai na samuwar ribosomes. Yawan wadannan polymerases a sel mafi girma wanda yake shawagi a kusa da alamar 40 dubu raka'a.
Yadda aka shirya?
Saboda haka, muna da farko RNA polymerase (prokaryotes-tsarin kwayoyin) yana dauke da kyau. A wannan yanayin, da manyan subunit, kamar yadda, lalle ne, da kuma wani babban adadin wasu high kwayoyin nauyi polypeptides, akwai fili rarrabe aikin da tsarin yankuna. A lokacin cloning kwayoyin halitta da kuma tantance su primary tsarin da aka gano da masana kimiyya evolutionarily conserved rabo na sarƙoƙi. Amfani mai kyau magana, da masu bincike da aka gudanar ma mutational analysis cewa yale mu mu yi magana game da aikin muhimmancin mutum yankuna. A saboda wannan dalili, ta amfani site-directed mutagenesis canza mutum polypeptide sarƙoƙi, da kuma irin modified amino acid subunits amfani a taro na enzymes da m bincike na Properties, wanda aka samu a cikin data Tsarin. An lura da cewa saboda da kungiyar na farko RNA polymerase a gaban alpha-amatina (a sosai mai guba abu, wanda aka samo daga mai kodadde toadstool) bai amsa.
aiki
Dukansu na farko da na biyu RNA polymerase iya zama a biyu siffofin. Daya daga cikin su za su iya aiki a fara da takamaiman kwafi. Na biyu - a DNA-RNA dogara polymerase. Wannan hali da aka bayyana a cikin most aiki na aiki. Subject karatu fiye, amma a yanzu mun san cewa shi ya dogara biyu kwafi dalilai, wanda ake kira a matsayin SL1 da UBF. Musamman ma karshen - cewa shi zai iya sadarwa kai tsaye tare da kiran kasuwa, yayin da SL1 UBF bukatar gaban. Ko da yake an yi gwaje tabbatar da cewa DNA-RNA dogara polymerase iya shiga a cikin kwafi a mafi kuma ba tare da gaban karshen. Amma ga al'ada aiki na wannan inji UBF ne har yanzu da ake bukata. Me ya sa haka? Muhimmanci don haka yanzu ya kasa kafa dalilin wannan hali. Daya daga cikin mafi mashahuri bayani da shawara cewa UBF umurni ne da wani irin stimulant rDNA kwafi a lokacin da ta ke tsiro da kuma tasowa. Lokacin da Allaha lokaci ya auku, sa'an nan kiyaye da ƙaramar bukata matakin na aiki. A wani bangare na kwafi dalilai ne ba m ga shi. Ga haka aiki RNA polymerase. The aiki na wannan enzyme damar goyi bayan sake kunnawa na kananan "gini tubalan" na jiki, saboda wanda shi ne kullum updated shekaru da dama.
Na biyu kungiyar na enzymes
Su aiki da aka kayyade ta taro na multiprotein hadaddun preinitsiatornogo promoters na biyu aji. Mafi sau da yawa wannan yana bayyana a cikin aikin na musamman da sunadarai - activators. Kamar yadda wani misali ne TBP. An hade dalilai da suke ɓangare na TFIID. Su - wani manufa domin p53, NF kappa B, da sauransu. Its tasiri a aiwatar da tsari da kuma samar da sunadaran gina jiki kira coactivators. Misalai ne Gcn5. Me ya sa muke bukatar wadannan sunadarai? Suna aiki ne kamar adaftan cewa siffanta hulda da activators da kuma abubuwan da suke a preinitsiatorny hadaddun. Don gyara kwafi ya faru, dole ne ka zama dole Mafarin dalilai. Duk da cewa shida daga gare su, kai tsaye hulɗa tare da kiran kasuwa na iya zama daya kawai. Ga wasu lokuta na bukatar preformed hadaddun na biyu RNA polymerase. Haka kuma, a lokacin da wadannan matakai ne m proximal abubuwa - kawai 50-200 nau'i-nau'i daga shafin inda kwafi aka fara. Sun ƙunshi wani nuni ne na dauri na activator sunadaran.
takamaiman siffofin
Shin da subunit tsarin da enzymes daga daban-daban asalin a kan su aikin rawa a cikin kwafi? A daidai amsar wannan tambaya shi ne ba, amma imani da cewa shi ne m tabbatacce. Yadda yi shi rinjayar RNA polymerase? Enzyme ayyuka sauki tsarin - wata iyaka kewayon kwafi na genes (ko ma wani karamin sashi). Misalai ne da kira na RNA primers Okazaki, niƙaƙƙun gaɓãɓuwa. The kiran kasuwa bayani dalla-dalla na RNA polymerases na kwayoyin cuta da kuma phages ne cewa enzymes ne kambun da sauki da tsari da kuma dabam- dabam suke. Wannan za a iya gani a cikin tsari na DNA kwafi a kwayoyin. Ko da yake ba za mu iya la'akari da wannan: hadaddun tsarin lokacin karatu genome T ko phage, a lokacin ci gaba, sai aka lura da cewa maimaita sauya sheka tsakanin daban-daban gene kwafi kungiyoyin, an gano cewa, cikin hadaddun amfani da wannan RNA polymerase rundunar. Wannan ne, mai sau enzyme a irin haka ba a jawo. Wannan yakan haifar da wani yawan sakamakon:
- RNA polymerase na eukaryotes da kwayoyin dole ne su iya gane daban-daban promoters.
- Wajibi ne cewa enzyme yana da wani takamaiman mayar da martani ga daban-daban sunadarai-gwamnoni.
- RNA polymerase dole ne ma su iya canza amincewa da bayani dalla-dalla na template DNA nucleotide jerin. Don yin wannan, yi amfani da wani iri-iri na gina jiki effectors.
Yana bi da jiki ta bukatar ƙarin "gini" abubuwa. Sunadaran taimake ka rubũtunsa da hadaddun na RNA polymerase zuwa cikakken gudanar da ayyuka. Wannan ya shafi, domin mafi, da enzymes hadaddun tsarin, a cikin abin da yiwuwa na aiwatar da wani m shirin kayyade bayani. Saboda matsaloli daban-daban, za mu iya tsayar da wani irin matsayi tsarin RNA polymerase.
Ta yaya aiwatar da kwafi?
Shin akwai wani gene alhakin sadarwa tare da RNA polymerase? Don fara da kwafi: aiwatar a eukaryotes faruwa a tsakiya. A prokaryotes, yana tafiya cikin kananan kwayoyin. Dangantaka tsakanin polymerase ne ainihin tsarin ka'ida na wani karin ma'abota mutum kwayoyin. A kan al'amurran da suka shafi na hulda iya cewa DNA ne kawai a samfuri kuma ba ya canza a lokacin kwafi. Tun da DNA ne cikakke enzyme, abu ne wasu, cewa wani gene ne ke da alhakin wannan polymer iya zama, amma zai kasance wani sosai tsawon lokaci. Kada mu manta cewa DNA ya ƙunshi 3.1 biliyan nucleotide sharan. Saboda haka, mafi dace a ce ga kowane irin RNA ya gana da DNA. Domin da ya kwarara daga cikin polymerase dauki bukatar makamashi da kuma ribonukle-ozidtrifosfato substrates. Idan wani suna kafa 3 ', 5'-phosphodiester shaidu tsakanin ribonukleozidmonofosfatami. Kwayar Komayya RNA kira zai fara a wasu jerin DNA (promoters). A tsari terminates a ƙarshe shafukan (karewa). The site, wanda aka hannu a nan ne ake kira transcriptional. A eukaryotes, akwai yawanci daya kawai gene, yayin da prokaryotes kuma iya mallaka mahara guda na code. Kowane transcriptional yana uninformative yankin. Suna located takamaiman nucleotide jerin cewa hulɗa tare da transcriptional kullum dalilai da aka ambata a sama.
Kwayan RNA polymerase
Wadannan kwayoyin daya enzyme ne ke da alhakin kira na mRNA, rRNA da tRNA. A talakawan polymerase kwayoyin yana da wani wajen 5 subunits. Biyu daga cikin wadannan bauta kamar yadda nauyin mambobi enzyme. Wani subunit da hannu a cikin qaddamarwa na kira. Akwai kuma wani bangaren na enzyme nonspecific don sadarwa tare da DNA. Kuma na karshe subunit an kawo RNA polymerase a wani aiki form. An lura da cewa enzyme kwayoyin ne ba a "free" kewayawa a cikin cytoplasm na kwayoyin. Lokacin da RNA polymerases ake amfani da shi, sa'an nan an ɗaure ba takamaiman DNA yankuna da ake jiran har sai da aiki mai kiran kasuwa, aka buɗe. A bit shagala daga cikin topic, shi ya kamata a ce cewa kwayoyin cuta sosai dace don nazarin sunadaran da su da tasiri a kan ribonucleic acid polymerase. Musamman dace domin su yi gwaji a kan ruri, ko hanawa daga cikin mutum abubuwa. Saboda su high haifuwa kudi na iya zama in mun gwada da sauri samun ake so sakamakon. Alas, da mutum nazari ba za a iya gudanar a irin wannan m taki godiya ga tsarin bambancin.
RNA polymerase "kama" in siffofin daban-daban?
Wannan ya zo a ma'ana ƙarshe da labarin. Babban hankali da aka biya zuwa eukaryotes. Amma har yanzu akwai archaea da ƙwayoyin cuta. Saboda haka kana so ka biya a bit na da hankali da kuma wadannan siffofin na rayuwa. A m aiki na Archean akwai daya kungiyar na RNA polymerases. Amma yana da matukar kama a da kaddarorin da uku ƙungiyoyi eukaryotes. Masana kimiyya da dama da aka bayar da shawarar cewa abin da za mu iya gani daga Arche zahiri wani juyin magabacin qware polymerases. Shi ne kuma mai ban sha'awa, da kuma tsarin da ƙwayoyin cuta. Kamar yadda a baya aka rubuta, ba duk wadannan kwayoyin suna da nasu polymerase. Kuma inda shi ne, shi ne guda subunit. An yi imani da cewa kwayar enzymes samu daga DNA polymerases, maimakon hadaddun RNA Tsarin. Ko da yake saboda da bambancin da wannan rukuni na kwayoyin daban-daban aiwatar gana a ba nazarin halittu inji.
ƙarshe
Alas, bil'adama ba tukuna da vsoy dole bayanai da ake bukata domin wani fahimtar da genome. Kuma cewa kawai ya iya yi! Kusan dukkan cututtuka su ne m kawai a kayyade akai - wannan ya shafi musamman ga ƙwayoyin cuta cewa kullum bamu da matsaloli ga cututtuka da sauransu. A mafi hadaddun da m cututtuka - su ma, a gaskiya, kai tsaye ko a kaikaice dogara a kan mutum genome. Idan mun koyi fahimta a kansu, kuma za su yi amfani da wannan ilimi don amfanin manyan yawan matsaloli da cututtuka za su kawai gushe. Yanzu wani abu da suka gabata, mutane da yawa a baya m cututtuka irin smallpox, annoba. Samun shirye su tafi mumps, whooping tari. Amma ba shakata, saboda mun fuskanci wani ma fi girma yawan daban-daban kalubale cewa kana bukatar ka sami amsar. Kuma za a iya samu, saboda shi ke faruwa yin haka.