Maumbirwo uye Mashandiro eRibosomes
Ribosomes ndeimwe yenhengo dzinonyanya kukosha mumasero, dzichiita basa rakananga mukugadzirwa kwemapuroteni. Mapuroteni ndiwo mamorekuru makuru anotarisira mabasa ese ehupenyu, kubva pakugadzira maumbirwo emasero, kukurumidzisa maitiro emakemikari kuburikidza nema enzymes, kudzora masaini pakati pemasero, uye kubatsira mukudzivirira kwemuviri. Nokudaro, kunzwisisa maumbirwo uye mashandiro e ribosomes zvinoreva kunzwisisa imwe yenzvimbo dzebasa rehupenyu padanho remamorekuru.
Kunzwisisa Ribosomes
MaRibosomes macromolecular complexes anoumbwa neribosomal RNA (rRNA) nemapuroteni eribosomal. MaRibosomes anowanikwa mumarudzi ese emasero—maprokaryotes (akadai sebhakitiriya) uye eukaryotes (akadai semhuka, zvirimwa, uye fungi). Kusiyana kwemaribosomes kuri mukuumbwa kwawo: rRNA haisi chikamu chechimiro chete asiwo inoita basa rekugadzirisa mukuumbwa kwepeptide bonds. Nemamwe mashoko, maribosomes anogona kufungwa nezvawo se "michina" yebiological inoshandura ruzivo rwemajini kubva ku mRNA kuenda kuma amino acid sequences anoumba mapuroteni.
Chimiro Chekutanga cheRibosomes
Kazhinji, ribosomes dzine ma subunits maviri: subunit diki ne subunit hombe. Ma subunits maviri aya anobatana panguva yekushandura (mRNA translation) uye anoparadzana kana asingashande. Subunit imwe neimwe inoumbwa ne rRNA ne protein muhuwandu hwakatarwa.
MaRibosome muProkaryotes (70S)
Mumasero eprokaryotic, ribosomes dzinonzi dzine saizi ye70S (S iyuniti yeSvedberg inoratidza mwero wekudonha kwemvura panguva ye centrifugation, kwete chiyero chakananga chehurefu). 70S ribosomes dzinosanganisira:
– Chikamu chidiki che30S, chine 16S rRNA uye mapuroteni akawanda.
– Chikamu chikuru che50S, chine mapuroteni e23S ne5S rRNA uye ribosomal.
Chikamu chidiki chinoita basa rakakosha mukuziva mRNA uye kuona nzvimbo yekutanga yekushandura, nepo chikamu chikuru chiri nzvimbo huru yekuumbwa kwepeptide bond.
MaRibosome muEukaryotes (80S)
Mumasero eukaryotic, ribosomes dzine saizi ye80S, inoumbwa ne:
– Chikamu chidiki che40S, chine 18S rRNA.
- Chikamu chikuru che60S, chine 28S, 5.8S, uye 5S rRNA.
MaEukaryotic ribosomes anowanzo kuve akaomarara, aine mapuroteni akawanda eribosomal uye zvimwe zvinhu zvinodzora maitiro ekushandura.
Nzvimbo yeRibosomes muSero
Ribosomes inowanikwa munzvimbo mbiri huru:
1. Ribosomes dzemahara dziri mu cytoplasm
Ma ribosome emahara anowanzo gadzira mapuroteni anozoshandiswa mu cytosol, semuenzaniso ma enzymes e metabolic kana mapuroteni e structural cell.
2. MaRibosome akabatana ne rough endoplasmic reticulum (rough ER)
MaRibosome akabatana ne rough ER anowanzo gadzira mapuroteni anoburitswa musero, anoiswa mu membrane yesero, kana kuendeswa kune mamwe ma organelle akadai se lysosomes. MaRibosome anobatanidza nekuti rough ER ine ma receptors anosangana nema ribosomes kana polypeptide chain iri kugadzirwa iine chiratidzo chaicho (signal peptide).
Pamusoro pezvo, ma organelle akadai se mitochondria nema chloroplast anewo ma ribosome awo, ayo akafanana zvikuru ne prokaryotic ribosomes (70S). Izvi zvinotsigira dzidziso ye endosymbiosis, iyo inoti mitochondria nema chloroplast zvakatangira kubva kuzvisikwa zve prokaryotic zvairarama pamwe chete mukati memasero emadzitateguru e eukaryotic.
Zvikamu zveRibosome: rRNA neProtein
Ribosomes inoumbwa nezvikamu zviviri zvikuru:
– Ribosomal RNA (rRNA): Iyi ndiyo mhando huru yeRNA uye inoumba framework uye catalytic centre ye ribosome. rRNA ndiyo inokonzera catalyst kuumbwa kwepeptide bonds (peptidyl transferase activity).
– Mapuroteni eRibosomal: anoshanda pakudzikamisa chimiro cherRNA, anobatsira kuunganidza mayuniti, uye anoshanda pamwe nezvinhu zvinoshandura.
Kusanganiswa kwe rRNA nemapuroteni kunoumba chimiro chakanyatsojeka chemativi matatu, zvichibvumira ribosomes kushanda nekukurumidza uye nemazvo.
Nzvimbo Dzinoshanda Mukati meRibosomes
Kana ribosome iri kushandura zvinhu, pane nzvimbo nhatu huru dzakakosha zvikuru, kunyanya pachikamu chikuru chezvikamu:
1. Nzvimbo A (Nzvimbo yeAminoacyl)
Nzvimbo yekupinda mu tRNA inotakura maamino acids zvichienderana ne mRNA codon.
2. Nzvimbo yeP (nzvimbo yePeptidyl)
Nzvimbo yetRNA inotakura cheni yepolypeptide iri kukura.
3. Nzvimbo E (Nzvimbo yekubuda)
Nzvimbo inobuda tRNA yakaburitsa amino acids.
Kufamba kwetRNA kubva kuA kuenda kuP uyezve kuenda kuE kunoitika apo ribosome "inoverenga" mRNA mabhesi matatu panguva imwe chete (codon necodon).
Basa reRibosomes muProtein Synthesis
Basa guru re ribosomes kushandura, uko kunoshandura nucleotide sequence mu mRNA kuita amino acid sequence. Kushandura kunowanzo kamurwa kuita zvikamu zvitatu:
1. Kutanga
Padanho iri, kachikamu kadiki ke ribosome kanonamatira ku mRNA kotsvaga start codon (kazhinji AUG). TRNA yekutanga ine methionine inobatanidzwawo. Kana start codon yavapo, kachikamu kakuru kanoungana kuti kagadzire ribosome inoshanda.
2. Kureba
Ribosome inofamba ichitevedza mRNA, ichitambanudza cheni yepolypeptide. TRNA inotakura amino acid inopinda panzvimbo yeA, uko inozobatanidzwa kune cheni iri panzvimbo yeP. Ribosome inobva yachinja codon imwe, yobvisa tRNA yoita kuti pave nenzvimbo yetRNA inotevera.
3. Kugumiswa
Kana ribosome yasangana ne stop codon (UAA, UAG, kana UGA), hapana tRNA inoenderana ne codon iyoyo. Pane kudaro, chinhu chinogumisa chinopinda uye chinoita kuti polypeptide cheni iburitswe. Ribosome inobva yapatsanurwa kuita ma subunit maviri uye inenge yagadzirira kushandiswazve.
Ribosomes seMaantibiotic Chinangwa
Ma ribosome eprokaryotic akasiyana nema ribosome eukaryotic. Musiyano uyu unoshandiswa mukurapa nekuti mamwe ma antibiotic anogona kudzivirira ma ribosome ebhakitiriya pasina kukuvadza zvakanyanya ma ribosome evanhu. Semuenzaniso:
– Tetracycline inodzivirira kupinda kwetRNA muA site.
- Chloramphenicol inodzivirira peptidyl transferase.
– Streptomycin inogona kukonzera kusanzwisiswa kwe mRNA.
Zvisinei, kushandiswa kwemishonga inorwisa mabhakitiriya kunofanira kunge kwakakodzera nekuti mabhakitiriya anogona kukura kusagona kurwisa utachiona kuburikidza nekuchinja kwemuviri kana dzimwe nzira dzekudzivirira.
Mhedziso
MaRibosome inhengo dzinokosha dzinoshanda senzvimbo yekugadzira mapuroteni. Maumbirwo eribosome ane zvikamu zviviri, chikuru nechidiki, nezvikamu zvikuru zviri mapuroteni e-rRNA neribosomal. MaRibosome ane nzvimbo dzeA, P, neE, dzinovimbisa maitiro ekushandura akarongeka uye akarurama. Kunze kwekutamba basa rakakosha mukugadzirwa kwemapuroteni ezvinodiwa nemasero, maRibosome anotarirwawo nemishonga yakasiyana-siyana inorwisa mabhakitiriya nekuda kwekusiyana kuripo pakati pemaribosome eprokaryotic neeukaryotic. Nekunzwisisa maumbirwo uye mashandiro emaribosome, tinogona kuona kuti maitiro ekutanga anochengetedza hupenyu akaoma uye akarongeka sei.
