Kapangidwe ndi Ntchito ya Ribosomes
Ma Ribosome ndi zigawo zofunika kwambiri m'maselo onse amoyo, zomwe zimagwiritsidwa ntchito ngati malo opangira mapuloteni, zomwe ndizofunikira kwambiri pakukula ndi kugwira ntchito kwa maselo. Kapangidwe kake kovuta komanso ntchito zatsatanetsatane za ma ribosome zakhala zikufufuzidwa kwambiri kwa zaka zambiri, zomwe zimapereka chidziwitso chakuya pa njira zazikulu za mamolekyu a moyo. Nkhaniyi ifotokoza mwatsatanetsatane kapangidwe ndi ntchito za ma ribosome, komanso kufunika kwawo kwachilengedwe komanso chidziwitso chamakono m'munda wa sayansi ya zamoyo.
Kapangidwe ka Ribosome
Ma Ribosome ndi ma ribonucleoprotein complexes opangidwa ndi ribosomal RNA (rRNA) ndi ma ribosomal proteins. Kawirikawiri, ma ribosome amagawidwa m'magulu awiri: gawo lalikulu ndi gawo laling'ono. Mu zamoyo za prokaryotic monga mabakiteriya, ma ribosome ndi 70S, ogawanika m'magulu ang'onoang'ono a 30S ndi gawo lalikulu la 50S. Mu zamoyo za eukaryotic, monga nyama ndi zomera, ma ribosome ndi 80S, opangidwa ndi gawo laling'ono la 40S ndi gawo lalikulu la 60S. Tiyenera kudziwa kuti "S" ikutanthauza mayunitsi a Svedberg, omwe ndi gawo losungira madzi lomwe limagwiritsidwa ntchito kuyerekeza kukula kwa tinthu mu centrifugation.
Gulu Laling'ono
Kagulu kakang'ono ka ribosome kamachita gawo lofunika kwambiri pakuwerenga mRNA (messenger RNA) kuti kasinthidwe kukhala mapuloteni. Mu ma ribosome a prokaryotic, kagulu kakang'ono ka 30S kamakhala ndi 16S rRNA ndi mapuloteni pafupifupi 21 a ribosomal. Mu ma ribosome a eukaryotic, kagulu kakang'ono ka 40S kamakhala ndi 18S rRNA ndi mapuloteni pafupifupi 33 a ribosomal. RRNA mu kagulu kakang'ono kamachita gawo lofunika kwambiri pakuzindikira ndi kumangirira mRNA komanso pogwirizanitsa tRNA (kusamutsa RNA) ndi ma codon oyenera pa mRNA panthawi yomasulira.
Gawo Lalikulu
Gawo lalikulu la ribosome ndi komwe kumapangidwira mgwirizano wa peptide pakati pa amino acid, njira yofunika kwambiri pakukulitsa unyolo wa polypeptide. Mu ma ribosome a prokaryotic, gawo lalikulu la 50S limapangidwa ndi 23S rRNA, 5S rRNA, ndi mapuloteni pafupifupi 34 a ribosomal. Mosiyana ndi zimenezi, mu ma ribosome a eukaryotic, gawo lalikulu la 60S limapangidwa ndi 28S rRNA, 5.8S rRNA, 5S rRNA, ndi mapuloteni pafupifupi 49 a ribosomal. Ma Ribozyme, magawo a RNA omwe amatha kuyambitsa machitidwe a mankhwala, amapezeka mu gawo lalikulu ndipo amachita gawo lofunika kwambiri mu prototypical catalysis ya mapangidwe a mgwirizano wa peptide.
Ntchito ya Ribosomes
Kumasulira kwa Mapuloteni
Ntchito yaikulu ya ma ribosome ndikuwongolera kumasulira kwa mapuloteni, njira yomwe ma ribosome amasinthira chidziwitso cha majini chomwe chili mu mRNA kukhala maunyolo a polypeptide omwe adzapindidwa kukhala mapuloteni ogwira ntchito. Njira yomasulira ikhoza kugawidwa m'magawo atatu akuluakulu: kuyambitsa, kutalikitsa, ndi kutha.
1. Kuyambitsa: Njirayi imayamba pamene gawo laling'ono la ribosome limalumikizana ndi mRNA pafupi ndi codon yake yoyambitsa. Zinthu zoyambitsa ndi ma tRNA oyambitsa omwe amanyamula ma amino acid methionine (mu eukaryotes) kapena formylmethionine (mu ma prokaryotes) amachita gawo lofunika kwambiri panjirayi. Kenako vutoli limasakanikirana ndi gawo lalikulu kuti lipange ribosome yogwira ntchito.
2. Kutalikirana: Pa siteji iyi, ribosome imayamba kuyenda motsatira mRNA, kuwerenga codon iliyonse ndikubweretsa tRNA yoyenera yokhala ndi amino acid yolondola. Apa ndi pomwe peptidyl transferase, enzyme yomwe ndi gawo la gawo lalikulu la ribozyme, imayambitsa kupangika kwa ma peptide bond pakati pa amino acid, ndikukulitsa unyolo wa polypeptide.
3. Kutha: Pamene ribosome ifika pa codon yomaliza pa mRNA, zinthu zotha zimazindikira codon iyi ndipo zimathandiza kutulutsidwa kwa unyolo wa polypeptide womalizidwa komanso kulekanitsidwa kwa ribosome ndi mRNA.
Kulamulira Kupanga Mapuloteni
Ma Ribosome nawonso amagwira ntchito yowongolera kapangidwe ka mapuloteni, kugwira ntchito ndi mapuloteni ena osiyanasiyana ndi ma RNA kuti atsimikizire kuti mapuloteni oyenera apangidwa muyeso wofunikira panthawi yoyenera. Lamuloli ndi lofunikira kwambiri pakusunga homeostasis ya maselo komanso kuyankha kusintha kwa chilengedwe.
Kuyang'anira Ubwino
Ma Ribosome ali ndi njira zomangira mkati kuti zitsimikizire ubwino wa mapuloteni opangidwa. Izi zikuphatikizapo njira zomwe zimazindikira zolakwika mu tRNA kapena mRNA ndikuletsa kutalikirana kapena kuyambitsa kuwonongeka kwa mamolekyu olakwika. Njirayi ndi yofunika kwambiri kuti zitsimikizire kuti mapuloteni ogwira ntchito okha ndi omwe amapangidwa, kuchepetsa chiopsezo cha kuwonongeka kwa maselo kapena kufa kwa maselo.
Kufunika kwa Zamoyo ndi Ntchito
Kumvetsetsa kapangidwe ndi ntchito ya ma ribosome sikuti ndikofunikira kokha pa sayansi yoyambira komanso kumagwiritsidwa ntchito kwambiri mu zamankhwala ndi sayansi ya zamoyo. Mwachitsanzo, maantibayotiki ambiri amagwira ntchito polimbana ndi ma ribosome a prokaryotic, kuletsa kupanga mapuloteni a mabakiteriya popanda kukhudza ma ribosome a eukaryotic. Kafukufuku wopitilira pa ma ribosome alinso ndi lonjezo lopanga njira zatsopano zochiritsira matenda osiyanasiyana.
Kupeza Kwatsopano
Kafukufuku waposachedwapa pogwiritsa ntchito njira zamakono monga X-ray crystallography ndi cryo-electron microscopy (Cryo-EM) wapereka chithunzi chatsatanetsatane cha kapangidwe ka ribosome. Zomwe zapezekazi zavumbula mawonekedwe a ribosome panthawi yomasulira, kulumikizana kwa zigawo za ribosome, komanso kuyanjana kwake ndi zinthu zina zomasulira. Chidziwitso chatsopanochi sichimangowonjezera kumvetsetsa kwathu njira zoyambira za ribosome komanso chimatsegula njira zatsopano zofufuzira zamankhwala ndi chitukuko cha mankhwala.
Mapeto
Ma Ribosome ndi makina ovuta komanso ofunikira kwambiri a mamolekyu omwe ali ndi udindo womasulira chidziwitso cha majini kukhala mapuloteni ogwira ntchito. Kudzera mu kapangidwe kawo kovuta ka ma subunit awiri komanso kuyanjana kolondola pakati pa mapuloteni a rRNA ndi ribosomal, ma ribosome amatha kupanga mapuloteni bwino kwambiri. Kumvetsetsa bwino kapangidwe ka ribosome ndi ntchito yake kukupitilirabe, zomwe zikupangitsa kuti kafukufuku wowonjezereka mu sayansi ya zamoyo zamamolekyu ndi ntchito zofunika kwambiri zachipatala. Zomwe zapezeka posachedwapa m'mundawu zapangitsa kuti ma ribosome akhale cholinga chachikulu pakuphunzira za moyo pamlingo wa mamolekyu.
