Icubungula - kuyinto ... RNA ukucutshungulwa (post-transcriptional RNA ukuguqulwa)

Sihlukanisa Kulesigaba ukuqaliswa ukwaziswa kwezakhi zofuzo kumaseli ezifana eukaryotes futhi prokaryotes ekhona.

Ukuhunyushwa lo mqondo

NgesiZulu, nkulumo isho ukuthi "impatho, kabusha." Icubungula - Ukwakheka kwezitho ovuthiwe RNA molecule kusukela pre-RNA. Ngamanye amazwi, lokhu iqoqo ukusabela eziholela ekuguquleni umbhalo oyinhloko umkhiqizo (pre-RNAs zezinhlobo ezahlukene) i-molecule kakade-esebenza ngayo.

Ngokuphathelene ukucutshungulwa p- futhi tRNA, ngokuvamile ihilela wayinquma emikhawulweni molecule izingcezwana extra. Uma sikhuluma mRNA, kungase kuqashelwe lapha ukuthi eukaryotes, le nqubo ithatha indawo ngezigaba eziningana.

Ngakho, ngemva siye safunda ukuthi ukucutshungulwa - kuyinto ukuguqulwa okulotshiweyo eyinhloko phakathi ovuthiwe RNA molecule kufanele uqhubekele ukucabangela izici zayo.

Izici eziyinhloko umqondo

Lokhu kungabandakanya lokhu okulandelayo:

• ukuguqulwa emikhawulweni yomibili engqamuzaneni kanye RNA, ngokuhamba ezingamalungu bajoyine ethize nucleotide ukulandelanisa ezibonisa indawo ekuqaleni (ekugcineni) kokusakaza;
• splicing - ukuwagwinya uninformative ribonucleic acid ukulandelanisa okuyinto zivumelana introns DNA.

Kepha prokaryotes, awayona kuncike ukucutshungulwa mRNA. It has ikhono ukusebenza kusukela ekupheleni zamagama.

Lapho wabe inqubo okukhulunywa?

Noma yimuphi ukucubungula umzimba RNA senzeka nucleus. It Kwenziwa enzyme letsite (eqenjini) yohlobo ngalunye lobukhulu molecule ngabanye. kusetshenzwe futhi zingavezwa imikhiqizo enjalo translation njengoba polypeptides zazo ngqo ukufunda kusukela mRNA. Lezi zinguquko angaphansi okuthiwa eyandulela molecule amaprotheni amaningi - collagen, amasosha, ama-enzyme, abanye hormone, bese uqala ukusebenza langempela emzimbeni.

Sifundile kakade ukuthi ukucutshungulwa - Ukwakheka kwezitho RNA abavuthiwe pre-RNA. Manje kubalulekile lokumba ubunjalo iningi ribonucleic acid.

RNA: ubunjalo chemical

Lena ribonucleic acid, okuyinto copolymer ka pyrimidine futhi purine ribonukleitidov ezixhunywe nomunye, njengoba nje kuyi-DNA 3 '- 5'-phosphodiester amabhuloho.

Naphezu kweqiniso lokuthi lezi izinhlobo ezimbili zama-molecule zifana, bayehluka ngezizathu eziningana.

Izimfanelo RNA ne-DNA

Okokuqala, ribonucleic acid elikhona carbon ezisalayo lapho Abut pyrimidine futhi purine lezisekelo, iqembu phosphate - ribose, e-DNA okufanayo - 2'-deoxyribose.

Okwesibili, izingxenye ezahlukene futhi pyrimidine. izingxenye Okufanayo yiwona ama-nucleotide adenine, ne-cytosine, i-guanine ne. Ngo-RNA, uracil likhona esikhundleni ne-thymine.

Okwesithathu, i-RNA 1 has a isakhiwo chain, futhi DNA - 2-iboshwe-molecule. Kodwa ribonucleic acid Strand izingxenye samanje polarity okuphambene (ukulandelana aphelele) ngalo uyakwazi uchungechunge olulodwa futhi ihlule ukwakha "hairpin" - isakhiwo, wanika izici Kuvunguza-2 (njengoba kuboniswe ngenhla).

Okwesine, ngoba i-RNA - neketanga olulodwa, okuyinto ongumphelelisi a DNA umucu wokuqala, i-guanine ne akudingeki therein ekhona okuqukethwe efanayo njengoba cytosine begodu i-adenine - uracil uthanda.

Okwesihlanu, kungenzeka i-RNA hydrolyzed ne alikhali 2 ', 3'-diesters ka mononucleotides eyindilinga. Indima hydrolysis Lesisemkhatsini udlala 2 ', 3', 5-triester, asikwazanga yakha phakathi kwenqubo efana DNA ngenxa ukungabi amaqembu wakhe 2'-hydroxyl. Ngokuqhathanisa nge-DNA ane-alikhali lability ka ribonucleic acid kuyinto impahla ewusizo ngezinhloso zokuxilonga, nokuhlaziya.

Ulwazi oluqukethwe RNA 1-balahleke ngokuvamile lwenteke njengendlela ukulandelana purine futhi pyrimidine lezisekelo, okungukuthi, i-polymer eyinhloko uchungechunge isakhiwo.

Lokhu ukulandelana kuyinto aphelele uchungechunge isakhi sofuzo (lokufaka ikhodi), ngazo RNA "readout." Ngenxa yalesi impahla ribonucleic acid-molecule kungaba ngokuqondile abophele uchungechunge esephepheni, kodwa akakwazi ukwenza lokhu nge-non-esephepheni DNA Strand. RNA ukulandelana, ngaphandle esikhundleni T U, elifana nalelo esiphathelene non-esephepheni uchungechunge izici zofuzo.

izinhlobo RNA

Cishe bonke abahilelekile ezifana amaprotheni biosynthesis. izinhlobo ezaziwayo zama-RNA:

1. Matrix (mRNA). Lokhu cytoplasmic ribonucleic acid molecule ukusebenza njengoba amaprotheni zamagama matrices.
2. Ribosomal (rRNA). Lokhu cytoplasmic RNA-molecule, silokhu sikhonza njengamaphayona izingxenye zesakhiwo ezifana ribosomes (organelles abathintekayo amaprotheni zamagama).
3. Ezokuthutha (tRNA). Lokhu molecule ukuthuthwa acid ribonucleic behileleka okuyinto ulwazi translation (translation) mRNA ibe ukulandelana amino acid amaprotheni kakade.

Enkulukazi ingxenye ye-RNA ye imibhalo yokuqala akhiqizwa amaseli eukaryotic, kuhlanganise amaseli mammalian, wadalula nucleus nokucekelwa inqubo, futhi udlala ulwazi cytoplasm noma indima kwesakhiwo.

Ngo amangqamuzana omuntu (cultured) atholakala isigaba acid encane yenuzi ribonucleic kungukuthi abahileleke ngokuqondile amaprotheni zamagama, kodwa ezithinta RNA ukucutshungulwa, kanye Imininingwane yeselula "izakhiwo." osayizi zabo zihlukene, ziqukethe 90 - 300 ama-nucleotide.

Ribonucleic acid - okokusebenza eziyisisekelo zofuzo ezivela eziningi amagciwane zezitshalo nezilwane. Amanye amagciwane equkethe RNA, ungalokothi ukudlula isinyathelo ezifana reverse umbhalo RNA ibe yi-DNA. Nokho abaningi isilwane amagciwane, isibonelo retrovirus, elinesimo translation reverse ufuzo RNA iqondiswe RNA ancike reverse umbhalo (DNA polymerase) ukwakha ikhophi DNA 2-Helical. Ezimweni eziningi kokuvela 2-Helical DNA okulotshiweyo ayiswa ufuzo okwengeziwe ukuhlinzeka Inkulumo zezakhi zofuzo ezibangelwa amagciwane kanye isikhathi yokusebenza yakamuva ikhophi RNA genomes (futhi viral).

Post-transcriptional ukulungiswa RNA

molecule bakhona kwemiqondo ne polymerases RNA, njalo kokumethemba ezisebenza ngasebenzi ukwenza, okungukuthi i-pre-RNA. Basuke uguqulwa abe-molecule ovuthiwe kakade kuphela emva kudlule olufanele ukulungiswa post-transcriptional RNA - ezigabeni nokuvuthwa kwawo.

Ukwakheka ovuthiwe mRNA wayefunde ngesikhathi zamagama kanye RNA polymerase II ngesinyathelo ukunwebeka. By 5'end we ezikhulayo kancane kancane Strand RNA 5'end enamathiselwe GTP ke wajinge wanamatsela orthophosphate. Ngaphezu kwalokho, nge obhekwe methylated guanine 7-methyl-GTP. Leli qembu elithile, elisetendeni ingxenye mRNA, ngokuthi "eneziqongo" (isigqoko noma ikepisi).

Kuye RNA zinhlobo (ribosomal kanye ezokuthutha,-matrix, njll) kokumethemba babhekana ukulungiswa ahlukahlukene ngokulandelana. Ngokwesibonelo, kokumethemba kuthiwa spliced mRNA, methylation, capping, polyadenylation, futhi ngezinye izikhathi ukuhlela.

Eukaryotes: umbono jikelele

iseli eukaryotic uba esizindeni eziphilayo, futhi liqukethe uhlamvu. Ngaphezu bacterium, archaea, zonke izinto eziphilayo kukhona zenuzi. Izitshalo, isikhunta, izilwane, kuhlanganise neqembu eziphilayo, okuthiwa protists - zonke isinyathelo eziphilayo eukaryotic. Bobabili bayi-1-cell kanye ezinamangqamuzana amaningi, kodwa konke epulanini isakhiwo yeselula. Kukholakala ukuthi lezi eziphilayo ezihlukahlukene ngakho kufanele umsuka esifanayo, ngenxa yalokho, iqembu yenuzi waqonda njengendlela taxon monophyletic besigaba eliphakeme.

Ngokusekelwe mbono othandwayo, eukaryotes sekukhona 1.5 - 2 billion edlule .. indima ebalulekile ukuziphendukela kwaso kunikezwa symbiogenesis - Symbiosis amaseli eukaryotic owawunesihloko core uyakwazi phagocytosis, futhi webhaktheriya, kugwinywe wakhe - sikakhokho ka plastids futhi mitochondria.

Prokaryotes: izici jikelele

Lokhu 1-cell eziphilayo awanayo i-nucleus (ukubhalisa), lonke organelles ulwelwesi (yangaphakathi). Okuwukuphela ezinkulu annular 2-chain DNA ezakha ingxenye enkulu impahla zofuzo engqamuzaneni ungesinye okungadingi akha eziyinkimbinkimbi ne amaprotheni histone.

Ukuze prokaryotes zihlanganisa archaea futhi gciwane, okuhlanganisa ukuhlanza cyanobacteria. Inzala enucleated amaseli - organelles eukaryotic - plastids, mitochondria. Basuke ihlukaniswe 2 taxa ngaphakathi isikhundla lesizinda: Archaea futhi bacterium.

La mangqamuzana awunawo imvilophi zenuzi, isembozo DNA senzeka ngaphandle ukubandakanywa histones. Osmotrofny uhlobo kuwo ukudla kwabo futhi liqukethe ukwaziswa kwezakhi eyodwa molecule ye-DNA okuyinto uvaliwe indandatho, futhi kukhona replicon eyodwa kuphela. Ngo prokaryotes kukhona organelles ukuthi kukhona ulwelwesi isakhiwo.

Ngokungafani eukaryotes kusukela prokaryotes

Isici eyisisekelo amaseli eukaryotic kuyinto okuhlobene nokuthola kuzo apharathasi kwezakhi zofuzo, okuyinto etholakala kuyi-nucleus, lapho ivikelwe igobolondo. DNA yabo komugqa elihlobene ne amaprotheni histones, nezinye amaprotheni wama-chromosomes, okuyizinto ngingekho amagciwane. Ngokuvamile, e yabo yokuphila umjikelezo ukwethula yenuzi 2 isigaba. Omunye has a isethi haploid wama-chromosomes, futhi kamuva ukuhlanganisa, 2 amaseli haploid akha diploid, okuyinto vele inalokhu iqoqo Ama-chromosomes e yesibili. Kwenzeka futhi ukuthi esikhathini esizayo lapho ingqamuzana ihlukana futhi iba haploid. Lolu hlobo umjikelezo wokuphila, kanye diploidy ngokuvamile, akuzona sici for prokaryotes.

Umehluko ezithakazelisayo kakhulu khona organelles ethize e eukaryotes, ezithinta siqu apharathasi yabo zofuzo nande ukwahlukana. Letakhi sizungezwe ulwelwesi. Lezi organelles kukhona mitochondria futhi plastids. Ngokusho isakhiwo zokuphila futhi kuyamangaza ezifana nalezo kwamagciwane. Lokhu isimo utshelwa ososayensi ukucabanga mayelana iqiniso lokuthi - inzalo ka eziphilayo ezibangelwa amagciwane Bangene Symbiosis nge eukaryotes.

Ngo prokaryotes, kukhona inombolo encane organelles nowodwa kuyo lizungezwe ulwelwesi yesibili. Abanalo reticulum endoplasmic, apharathasi Golgi, le lysosomes.

Omunye umehluko obalulekile 1 kusuka eukaryotes prokaryotes - khona endocytosis esenzeka eukaryotes, kuhlanganise phagocytosis emaqenjini amaningi. I last yikhono uthwebule ngokufaka ulwelwesi bubble ke inhlabamkhosi izinhlayiya ahlukahlukene okuqinile. Le nqubo inikeza umsebenzi obalulekile okuvikela umzimba. Okuvela phagocytosis, mhlawumbe ngenxa yokuthi ukuthi amaseli zabo usayizi isilinganiso. eziphilayo Prokaryotic kuyinto engenakuqhathaniswa kancane, ngenxa yalokho, phakathi kwemvelo eukaryotes, kwakukhona imfuneko elihlobene ne supply amaseli esibalulekile ukudla. Ngenxa yalokho, le izilwane ezidla ezinye kuqala ezithathekayo uvele phakathi kwabo.

Icubungula njengoba omunye izigaba amaprotheni biosynthesis

Lesi sigaba sesibili, oqala emva umbhalo. Ukucubungula amaprotheni kwenzeka kuphela eukaryotes. Lokhu nokuvuthwa we mRNA. Ukuze enembile, kuba ukususwa yezwe engangqubuzani khomba i-protein, nokulawula ngokujoyina.

isiphetho

Kulesi sihloko sichazwe esimele ukucutshungulwa (biology). Futhi wathi lokhu RNA ubala izinhlobo zayo kanye ukuguqulwa post-transcriptional. Kubhekwe izici esasenza eukaryotes futhi prokaryotes.

Ekugcineni kuwufanele ukukhumbuza ukuthi ukucutshungulwa - Ukwakheka kwezitho RNA abavuthiwe pre-RNA.