Maumbirwo eRNA muMajini
Ribonucleic acid (RNA) imorekuru inokosha muhurongwa hwemajini hwezvinhu zvipenyu zvese. Kunyange zvazvo DNA ichiwanzonzi "kuchengetwa" kweruzivo rwemajini, RNA ine basa guru: inokopa, inotakura, inoshandura, uye inotoronga ruzivo irworwo kuitira kuti rugone kushandurwa kuita mabasa ehupenyu. Kusiyana kweRNA hakusi mubasa rayo chete asiwo muchimiro chayo chinochinjika uye chakasiyana-siyana. Maumbirwo eRNA anobvumira molekyulu iyi kuita mabasa akawanda panguva imwe chete, kubva pakubatanidza kutaura kwemajini kusvika pakugadzirisa maitiro emakemikari. Chinyorwa chino chinokurukura maumbirwo eRNA uye hukama hwayo nebasa rayo muhurongwa hwemajini.
1. Kunzwisisa RNA nezvikamu zvayo
RNA ipolymer inoumbwa nemayuniti anodzokororwa anonzi nucleotides. Nucleotide yega yega yeRNA ine zvikamu zvikuru zvitatu: shuga yeribose, boka rephosphate, uye base yenitrogenous. Mabhesi enitrogenous muRNA anosanganisira adenine (A), guanine (G), cytosine (C), uye uracil (U). Misiyano yakakosha kubva kuDNA kushandiswa kweuracil pachinzvimbo chethymine uye rudzi rweshuga inoshandiswa (ribose muRNA, deoxyribose muDNA).
Kuvapo kweboka rehydroxyl (-OH) paatomu yekabhoni ye2' yeribose kunoita kuti RNA ive nyore kuita uye isagadzikana kupfuura DNA. Zvisinei, "kusagadzikana" uku kunobatsira mumamiriro ezvinhu ehupenyu nekuti RNA inowanzogadzirwa semorekuru yenguva pfupi inogadzirwa nekukurumidza uye inopwanyika nekukurumidza sezvinodiwa nesero.
2. Chimiro chikuru: kutevedzana kwe nucleotide sekodhi yeruzivo
Chimiro chikuru cheRNA chinoreva kutevedzana kwemanucleotide ari muRNA chain. Kutevedzana uku kunochengeta ruzivo—sese se template yekugadzira mapuroteni uye se regulatory signal. Mu messenger RNA (mRNA), kutevedzana kwemanucleotide kwakarongwa muma codons matatu-base anoshandurwa kuita amino acid sequence yeprotein. Mune mamwe marudzi eRNA, akadai se rRNA kana tRNA, chimiro chekutanga chinosarudzawo nzvimbo yenzvimbo dzakakosha dzinoumba mapete ane hunhu uye nzvimbo dzinoshanda.
Maumbirwo epakutanga haashande ari ega. MuRNA, ruzivo rwe "coding" ne "structural" runopindirana: kutevedzana kwebase hakungogumiri pakuona meseji yemajini chete asiwo kunoona kugona kweRNA kugadzira ma base pairs emukati anogadzira maumbirwo epamusoro.
3. Chimiro chechipiri: mabhesi maviri uye mafold akajairika eRNA
Maumbirwo eRNA secondary structure ndiwo maitiro e intramolecular base pairs anoumba zvinhu zvakaita se helices, hairpins, loops, bulges, uye junctions. Nheyo huru yekubatanidza base muRNA inowanzo tevera mutemo wekuwedzera: A pairs neU, uye G pairs neC. Pamusoro pezvo, RNA inowanzo gadzirawo non-canonical base pairs dzakadai seG-U wobble, iyo yakagadzikana uye yakakosha pakushanda kwemaRNA mazhinji.
Kupeta kwechipiri kunoitika nekuti tambo imwe chete yeRNA inogona kupeta nekuumba ma hydrogen bonds pakati pemabhesi anoenderana panzvimbo dzakasiyana. Maumbirwo echipiri aya akakosha nekuti:
1. Kusimbisa mamorekuru eRNA munzvimbo inoshanduka yemasero.
2. Kugadzira nzvimbo dzinozivikanwa dzemamwe mapuroteni kana RNA.
3. Kudzora maitiro ehupenyu, semuenzaniso kuona kana mRNA ichishandurwa zviri nyore kana kuti ichidziviswa.
Muenzaniso wakajeka i tRNA, ine chimiro chechipiri chakafanana ne "cloverleaf." Chimiro ichi chine maoko akati wandei, kusanganisira ruoko rwe anticodon uye ruoko rwe amino acid acceptor, rimwe nerimwe rine basa raro.
4. Maumbirwo epamusoro: chimiro chine mativi matatu chinosarudza mashandiro
Maumbirwo eRNA matatu anokonzerwa nekubatana kwezvikamu zvechimiro chechipiri. Padanho iri, RNA inoumba kupeta kwakaoma kuburikidza nemasimba akasiyana-siyana, akadai sekuwedzera mahydrogen bonds, base stacking interactions, uye rubatsiro rwemaion (semuenzaniso, Mg²⁺) anobvisa negative charge pa phosphate backbone.
Maumbirwo epamusoro akakosha nekuti mabasa mazhinji eRNA anoenderana nechimiro chayo chemativi matatu. Semuenzaniso:
– tRNA pakupedzisira ine chimiro cheL munzvimbo ine mativi matatu. Chimiro ichi chinobvumira magumo ekubatanidza amino acid kuti aiswe zvakanaka zvichienderana neanticodon inoverenga mRNA codon.
- rRNA inoumba musimboti wechimiro che ribosome, uye fold yayo yepamusoro inogadzira dudziro chaiyo ye "factory".
– Ribozymes, idzo dziri maRNA anokonzeresa mabhakitiriya, dzinoshandisa zvakanyanya mafomu echitatu kugadzira nzvimbo dzinoshanda dzakadai sema enzymes emapuroteni.
Saka, RNA haisi "nhume" chete. Inogona kuva chimiro chehupenyu chakaoma uye chinoshanda.
5. Mhando dzeRNA uye hukama hwechimiro-basa
Muhurongwa hwemajini, kune mhando dzinoverengeka dzeRNA dzinozivikanwa zvikuru:
a. mRNA (mutumwa RNA)
mRNA inotakura ruzivo rwemajini kubva kuDNA iri munucleus (mueukaryotes) kuenda kuma ribosome ari mu cytoplasm kuti ashandurwe kuita mapuroteni. Maumbirwo e eukaryotic mRNA anowanzo sanganisira chivharo che 5', nzvimbo isina kushandurirwa (UTR), furemu yekuverenga (ORF), uye muswe we poly-A pamucheto we 3'. Zvinhu izvi zvinopesvedzera kugadzikana kwe mRNA, kushanda zvakanaka kweshanduro, uye nzvimbo mukati mesero.
b. tRNA (kutamisa RNA)
tRNA inoshanda seadaptor inobatanidza mRNA codons nemaamino acids ayo anoenderana. Chimiro chechipiri checloverleaf uye chimiro chetertiary chakaita seL zvinoita kuti tRNA ikwanise: (1) kuzivikanwa neenzyme aminoacyl-tRNA synthetase, (2) kupinda mu ribosome, uye (3) kubatanidza maanticodon nemacodons nemazvo.
c. rRNA (ribosomal RNA)
rRNA chinhu chakakosha muma ribosome uye ine basa rakakosha mukushandura. Zvinofadza kuti ma ribosome "ma ribozymes" makuru: chikamu chinokonzeresa kugadzirwa kwe peptide bond chinonyanya kuitwa ne rRNA, kwete protein. Kubudirira kwebasa re ribosomes kunoenderana zvakanyanya nechimiro chakaomarara che rRNA.
d. RNA inodzora
Kuwedzera kumarudzi matatu makuru, maRNA madiki akawanda anoshanda kudzora kutaurwa kwemajini, akadai semiRNA (microRNA), siRNA (small interferensing RNA), uye lncRNA (long non-coding RNA). Magadzirirwo eRNA anowanzo kuve nema hairpins, kana kuti nzvimbo dzinobatanidza ma base, izvo zvinovabvumira kubatana kune ma mRNA uye kudzivirira kushandurwa kana kukonzera kuora kwe mRNA.
6. RNA mukukopa, kunyora, uye kugadzirisa majini
RNA inobatanidzwa zvakananga muzvikamu zvakasiyana-siyana zvekuyerera kwemashoko ejini. Panguva yekunyorwa, RNA polymerase inogadzira RNA zvichibva patemplate yeDNA. MuEukaryotes, RNA ichangobva kuumbwa (pre-mRNA) inogadziriswa: kuwedzera cap, intron splicing, uye polyadenylation. Maumbirwo eRNA anogona kukanganisa splicing, sezvo mamwe mapeta anogona kuvharidzira kana kusimbisa nzvimbo dzesplicing.
RNA inobatanidzwawo mukudzokororwa kwemavhairasi akasiyana. Mumavhairasi eRNA, majini acho iRNA, saka chimiro cheRNA yehutachiona chinowanzogadzirwa kuti chishande zvakanaka: chinogona kushanda segenome uye semRNA. Mamwe mavhairasi anoshandisa maumbirwo chaiwo eRNA kudzivirira dziviriro yemasero kana kuwedzera kugona kwekudzokororwa.
7. Maonero ekushanduka-shanduka: fungidziro yenyika yeRNA
Imwe yepfungwa huru mukushanduka-shanduka kwehupenyu hwemhuka ipfungwa ye "RNA world". Iyi fungidziro inoratidza kuti pakutanga kwehupenyu, RNA ingangodaro yakashanda mabasa maviri sedura reruzivo rwemajini uye chinhu chinoita kuti pave nekuchinjana, isati yapatsanurwa kuita DNA (yakasimba pakuchengetwa) uye mapuroteni (akasiyana-siyana pakugadziriswa). Kuchinjika kwechimiro cheRNA kunotsigira pfungwa iyi, sezvo RNA inogona kunyora ruzivo ichipetwa munzvimbo dzinoshanda pakugadziriswa.
Mhedziso
Maumbirwo eRNA ndiwo musimboti webasa rayo mu genetics. Kubva pachimiro chayo chikuru, chinochengeta nucleotide sequences, kusvika pachimiro chayo chechipiri, chinoumba hairpin-like folds, kusvika pachimiro chayo chetatu, chinoita mabasa akaomarara emativi matatu, RNA inoratidza kugona kwayo kwakasarudzika semorekuru inoshanda zvakawanda. Mhando dzakasiyana dzeRNA dzinoibvumira kushanda semutakuri weruzivo, adapter yekushandura, muvaki we ribosome, mugadziri we gene expression, uye kunyange catalyst ye biological. Kunzwisisa maumbirwo eRNA kunoreva kunzwisisa imwe yenheyo huru dzehupenyu, kugadzira nzira yekushandisa biotechnology uye medical senge RNA-based therapy, mRNA vaccines, uye kutonga kwakarurama kwe gene expression.
