Ua - yog ... RNA ua (post-transcriptional RNA kev hloov kho)

Nws distinguishes no theem qhov kev siv ntawm uas twb muaj lawm genetic ntaub ntawv nyob rau hauv lub hlwb xws li eukaryotes thiab prokaryotes.

Txhais lus ntawm no notion

Nyob rau hauv lus Askiv, lub sij hawm txhais tau tias "kev kho mob, ub." Ua - yog lub tsim ntawm mature RNA molecules los ntawm pre-RNA. Nyob rau hauv lwm yam lus, qhov no set kev tshua uas ua rau lub transformation ntawm thawj transcription product (lub pre-RNAs ntawm ntau hom) nyob rau hauv ib tug twb-ua tau hauj lwm molecule.

Nrog kev xav txog cov kev ntawm cov p- thiab tRNA, nws feem ntau los cia rau txiav tawm qhov xaus ntawm lub lwg me me ntawm lub ntxiv thooj. Yog hais tias peb tham txog cov mRNA, tej zaum nws yuav tsum tau muab sau no tias nyob rau hauv eukaryotes, cov txheej txheem yuav siv sij hawm qhov chaw nyob rau hauv ob peb ua sawv.

Yog li ntawd, tom qab uas peb tau kawm hais tias tus ua - yog lub transformation ntawm cov thawj tseem ceeb mus rau hauv lub mature RNA molecule, yuav tsum npaj mus rau lub saib xyuas ntawm nws cov nta.

Cov yam ntxwv tseem ceeb ntawm lub tswvyim

Qhov no yuav muaj xws li cov nram qab no:

• kev hloov kho ob hnub ntawm lub molecule thiab RNA, nyob rau hauv lub chav kawm ntawm uas lawv tuaj koom los ntawm ib qho nucleotide sequences uas qhia qhov chaw pib (xaus) ntawm lub tshaj tawm hauv xov;
• splicing - clipping uninformative ribonucleic acid sequences uas sib haum mus rau introns DNA.

Raws li rau prokaryotes, lawv yuav tsis raug mus rau lub mRNA ua. Nws muaj lub peev xwm mus ua hauj lwm los ntawm lub kawg ntawm lub synthesis.

Qhov twg hais cov txheej txheem nyob rau hauv lo lus nug?

Tej kab mob RNA ua yuav siv sij hawm qhov chaw nyob rau hauv lub nucleus. Nws yog nqa tawm los ntawm kev enzymes (lawv pab pawg neeg) rau txhua tus neeg hom molecules. ua tej zaum kuj yuav tsum tau raug mus xws translation khoom raws li cov polypeptides uas yog ncaj qha mus nyeem los ntawm cov mRNA. Cov kev hloov no yog kev kawm rau hauv lub thiaj li hu ua precursor molecules ntawm feem ntau cov nqaijrog - collagen, lub cev, digestive enzymes, ib co tshuaj hormones, thiab ces pib lub sij hauj lwm ntawm lub cev.

Peb twb kawm tau hais tias cov ua - yog lub tsim ntawm mature RNA los ntawm pre-RNA. Tam sim no nws yog tsim nyog los delve rau hauv lub qhov ntawm feem ntau ntawm ribonucleic acid.

RNA: cov tshuaj xwm

Qhov no yog ib ribonucleic acid, uas yog ib tug copolymer ntawm pyrimidine thiab purine ribonukleitidov uas yog kev cob cog rua nrog txhua lwm yam, cia li raws li nyob rau hauv lub DNA 3 '- 5'-phosphodiester choj.

Txawm tias muaj tseeb hais tias cov ob hom ntawm molecules yog zoo sib xws, lawv txawv nyob rau hauv ob peb lub chaw.

Tus yam ntxwv ntawm RNA thiab DNA

Firstly, ribonucleic acid yog tam sim no nyob rau hauv cov pa roj carbon residue uas abut pyrimidine thiab purine bases, lub phosphate pab pawg neeg - ribose, nyob rau hauv DNA tib yam - 2'-deoxyribose.

Ob txhais, qhov sib txawv Cheebtsam thiab pyrimidine. Zoo li cov Cheebtsam yog cov nucleotides adenine, cytosine, guanine. Nyob rau hauv RNA, uracil yog tam sim no es tsis txhob ntawm thymine.

Peb, RNA 1 muaj ib cov saw qauv, thiab DNA - 2-chained molecule. Tab sis ribonucleic acid strand tam sim no feem ntawm opposite polarity (complementary ib theem zuj zus) los ntawm cov uas nws muaj peev xwm sawv ntawm ib cov saw thiab los khov rau ntawd tsim "hairpin" - qauv, muab tej txiaj ntsim nrog cov yam ntxwv ntawm cov kauv-2 (raws li qhia saum toj no).

Plaub, vim hais tias cov RNA - ib zaug xwb saw, uas yog complementary mus rau ib tug thawj DNA strand, guanine yuav tsis tam sim no nyob rau ntawd nyob rau hauv tib lub ntsiab lus raws li cov cytosine thiab adenine - uracil nyiam.

Fifth, lub RNA tej zaum yuav hydrolyzed nrog alkali mus rau 2 ', 3'-diesters ntawm cyclic mononucleotides. Lub luag hauj lwm ntawm intermediate hydrolysis plays 2 ', 3, 5-triester, tsis tau tsim thaum lub sij hawm tus txheej txheem zoo ib yam li DNA vim lub tsis tuaj kawm ntawv nws 2'-hydroxyl pawg. Los ntawm kev sib piv nrog DNA alkaline lability ntawm ribonucleic acid yog ib pab cuab yeej rau diagnostic cov hom phiaj, thiab rau kev tsom xam.

Cov ntaub ntawv muaj nyob rau hauv lub 1-tso tseg RNA yog feem ntau siv raws li ib tug sib lawv liag ntawm purine thiab pyrimidine bases, uas yog, ib tug thawj polymer saw qauv.

Qhov no ib theem zuj zus yog complementary saw noob (encoding), uas cov RNA "readout." Vim li no cov khoom teejtug uas yog ribonucleic acid molecule yuav hais khi rau cov coding saw, tab sis yog tsis muaj peev xwm ua li no uas tsis-coding DNA strand. RNA ib theem zuj zus, tsuas yog rau kev hloov T U, zoo ib yam li uas hais txog ib tug uas tsis yog-coding saw noob.

hom ntawm RNA

Yuav luag tag nrho cov ntawm lawv yog muab kev koom tes nyob rau hauv tus txheej txheem xws li protein biosynthesis. Paub cov hom ntawm RNA:

1. Matrix (mRNA). Qhov no cytoplasmic ribonucleic acid molecules uas ua raws li protein synthesis matrices.
2. Ribosomal (rRNA). Qhov no cytoplasmic RNA molecule, liab li yam ntxwv Cheebtsam xws li ribosomes (organelles muab kev koom tes nyob rau hauv protein synthesis).
3. Tsheb thauj mus los (tRNA). Qhov no thauj molecules ntawm ribonucleic acids uas yog muab kev koom tes nyob rau hauv cov neeg txhais lus (translation) mRNA ntaub ntawv mus rau hauv ib tug sib lawv liag ntawm amino acids ntawm cov nqaijrog twb.

Ib tug ntau heev ib feem ntawm lub RNA ntawm cov thawj transcripts uas ua nyob rau hauv eukaryotic hlwb, nrog rau mammalian hlwb, raug nyob rau hauv lub nucleus degradation txheej txheem, thiab plays cov ntaub ntawv nyob rau hauv lub cytoplasm los yog cov yam ntxwv lub luag hauj lwm.

Nyob rau hauv tib neeg lub hlwb (kuaj) pom ib tug hauv chav kawm ntawv ntawm cov me me nuclear ribonucleic acids uas yog tsis ncaj nraim kev koom tes nyob rau hauv protein synthesis, tab sis rau RNA ua, raws li tau zoo raws li tag nrho cov cellular "architecture." Lawv ntau thiab tsawg pab sib txawv, lawv muaj 90 - 300 nucleotides.

Ribonucleic acid - qhov yooj yim genetic ntaub ntawv los ntawm ib tug xov tooj ntawm cov kab mob ntawm cov nroj tsuag thiab tsiaj txhu. Ib txhia cov kab mob uas muaj RNA, yeej tsis dhau xws kauj ruam raws li qhov rov qab transcription ntawm RNA rau hauv DNA. Txawm yog muaj ntau yam tsiaj cov kab mob, piv txwv li retroviruses, yus muaj los ntawm ib tug rov qab translation ntawm genome RNA qhia RNA-dependent rov qab transcription (DNA polymerase) tsim 2-helical DNA daim ntawv. Nyob rau hauv feem ntau tshwm 2-helical DNA ntawv tseem ceeb yog tswvcuab rau hauv lub genome ntxiv muab kev qhia ntawm tus kab mob cov noob thiab cov kev khiav hauj lwm lub sij hawm ntawm qhov tseeb daim ntawv RNA genomes (thiab kab mob).

Post-transcriptional kev hloov kho ntawm RNA

Nws molecules yog tsim nrog rau cov RNA polymerases, yeej ib txwm feem tsaug zog precursors rau ua, namely lub pre-RNA. Lawv hloov mus rau hauv ib tug twb paub tab molecule tsuas yog tom qab kis tau cov post-transcriptional kev hloov kho ntawm RNA - cov theem ntawm nws cov maturation.

Cov tsim ntawm mature mRNA tau nyeem thaum lub sij hawm synthesis thiab RNA polymerase II nyob rau hauv kauj ruam elongation. Los ntawm 5'end ntawm lub maj loj hlob strand RNA txuas 5'end GTP, ces cleaved orthophosphate. Ntxiv mus, nrog lub advent ntawm methylated guanine 7-methyl-GTP. Qhov no tej pab pawg neeg, uas yog nyob rau hauv ib feem ntawm lub mRNA, hu ua "capped" (lub kaus mom los yog cap).

Nyob ntawm seb lub hom RNA (ribosomal thiab thauj, matrix, etc.) precursors yog raug mus rau ntau yam successive kho. Piv txwv li, lub precursors yog spliced mRNA, methylation, capping, polyadenylation, thiab tej zaum kuj editing.

Eukaryotes: ib tug general txheej txheem cej luam

eukaryotic cell ua raws li cov sau muaj sia nyob, thiab nws muaj ib tug tseem. Nyob rau hauv tas li ntawd mus cov kab mob, archaea, tag nrho cov kab mob yog nuclear. Nroj tsuag, fungi, tsiaj txhu, xws li ib pab pawg neeg ntawm cov kab mob no, hu ua protists - tag nrho cov ua eukaryotic kab mob. Lawv yog cov ob 1-cell thiab multicellular, tab sis tag nrho cov kev npaj ntawm cov cellular qauv. Nws yog ntseeg hais tias cov no yog cov li miv kab mob muaj tib lub hauv paus chiv keeb, raws li ib tug tsim nyog tau, ib pab pawg neeg ntawm nuclear ntaus nqi raws li ib tug monophyletic taxon ntawm lub siab tshaj plaws nyob qib.

Raws li qhov nrov hypothesis, eukaryotes sawv 1.5 - 2 billion xyoo dhau los .. Tseem ceeb luag hauj lwm nyob rau hauv lawv cov evolution yog muab symbiogenesis - symbiosis eukaryotic hlwb, uas muaj cov tub ntxhais uas muaj peev xwm ntawm phagocytosis, thiab kab mob, nqos nws - progenitor ntawm plastids thiab mitochondria.

Prokaryotes: general yam ntxwv

Qhov no 1-cell kab mob uas tsis muaj keeb (sau npe), tus so ntawm daim nyias nyias organelles (internal). Lub tsuas loj annular 2-saw DNA molecule muaj cov loj ib feem ntawm lub caj khoom ntawm tus xovtooj ntawm yog ib tug uas tsis tsim ib tug complex nrog lub histone proteins.

Rau prokaryotes xws li archaea thiab cov kab mob, xws li cyanobacteria. Xeeb leej xeeb ntxwv enucleated hlwb - eukaryotic organelles - plastids, mitochondria. Lawv muab faib ua 2 taxa nyob rau hauv lub sau nyob qib: Archaea thiab kab mob.

Cov hlwb tsis muaj lub nuclear lub hnab ntawv, lub DNA ntim yuav siv sij hawm qhov chaw tsis muaj kev koom tes ntawm histones. Osmotrofny cov zaub mov hom thiab muaj cov kev tshuaj ntsuam genetic khoom siv ntawm ib tug DNA molecule uas yog kaw nyob rau hauv ib lub nplhaib, thiab tsuas muaj tib tug replicon. Nyob rau hauv prokaryotes yog organelles uas yog daim nyias nyias qauv.

Tsis zoo li eukaryotes los ntawm prokaryotes

Cov yuav tsum muaj feature ntawm eukaryotic hlwb yog lwm yam kev mus rau lub nrhiav nyob rau hauv lawv lub caj apparatus, uas yog nyob rau hauv lub nucleus, qhov twg nws yog kev tiv thaiv los ntawm ib tug plhaub. Lawv linear DNA txuam nrog cov nqaijrog histones, lwm cov nqaijrog ntawm chromosomes, uas yog tsis tuaj kawm ntawv nyob rau hauv cov kab mob. Feem ntau, nyob rau hauv lawv lub neej voj voog tuaj nuclear 2 theem. Ib tug muaj ib tug haploid txheej chromosomes, thiab tom qab phiajcim, 2 haploid hlwb tsim ib tug diploid, uas twb muaj lub thib ob txheej ntawm chromosomes. Nws kuj tshwm sim hais tias tom ntej no lub sij hawm ib tug cell faib dua yuav haploid. Qhov no zoo ntawm lub neej voj voog, raws li zoo raws li diploidy nyob rau hauv Feem ntau, yog tsis yam ntxwv rau prokaryotes.

Cov feem nthuav txawv yog lub xub ntiag ntawm kev organelles nyob rau hauv eukaryotes, uas muaj lawv tus kheej kev tshuaj ntsuam genetic apparatus thiab muab los ntawm division. Cov lug yog surrounded los ntawm ib tug nyias nyias. Cov organelles yog cov mitochondria thiab plastids. Raws li cov qauv ntawm lub neej thiab lawv yog ceeb zoo ib yam li cov neeg ntawm cov kab mob. Qhov no teeb meem sim hawm caij nyoog zaum yuav tau xav txog qhov tseeb hais tias lawv - lub xeeb leej xeeb ntxwv ntawm cov kab mob kab mob uas tau nkag mus rau hauv symbiosis nrog eukaryotes.

Nyob rau hauv prokaryotes, muaj ib tug me me muaj pes tsawg tus ntawm organelles, tsis muaj leej twg uas yog surrounded los ntawm ib tug thib ob daim nyias nyias. Lawv tsis muaj lub endoplasmic reticulum, lub Golgi apparatus, lub lysosomes.

Ib qho tseem ceeb sib txawv 1 ntawm eukaryotes prokaryotes - muaj endocytosis tshwm sim nyob rau eukaryotes, xws li phagocytosis nyob rau hauv feem ntau pawg. Lub xeem yog cov muaj peev xwm mus ntes tau los ntawm kev nkag mus kawm ib tug npuas daim nyias nyias, ces zom cov ntau yam khoom hais. Qhov no txoj kev muab ib qho tseem ceeb tiv thaiv nuj nqi nyob rau hauv lub cev. Cov tshwm sim ntawm phagocytosis, txawm vim lub fact tias lawv lub hlwb muaj ib tug nruab nrab loj. Prokaryotic kab mob yog incomparably tsawg, raws li ib tug tsim nyog tau, thaum lub sij hawm lub evolution ntawm eukaryotes, muaj ib tug yuav tsum tau nrog cov mov ntawm lub hlwb ib tug tseem ceeb npaum li cas ntawm cov khoom noj. Raws li ib tug tshwm sim, tus thawj rooj noj txhom nyob nrog lawv.

Ua raws li ib tug ntawm cov theem ntawm cov protein biosynthesis

Qhov thib ob theem, uas yuav pib tom qab transcription. Ua ntawm cov nqaijrog tshwm sim xwb nyob rau hauv eukaryotes. Qhov no maturation ntawm lub mRNA. Yuav kom leej, nws yog ib qhov kev tshem tawm ntawm thaj av uas tsis code rau protein, thiab koom tswj.

xaus

Nyob rau hauv no tsab xov xwm nws yog piav hais tias nruab nrab yog ua (txog biology). Tsis tas li ntawd hais tias qhov no RNA teev nws hom thiab post-transcriptional kev hloov kho. Xam tias yog yus nta ntawm eukaryotes thiab prokaryotes.

Thaum kawg nws yog tsim nyog los nco ntsoov tias lub ua - yog lub tsim ntawm mature RNA los ntawm pre-RNA.