Vashandi muKutonga kweMajini eBacterial
Kudzora majini kugona kwemasero "kuvhura" kana "kudzima" kuratidzwa kwemajini sezvinodiwa. Mumabhakitiriya, kudzorwa uku kwakakosha nekuti anogara munzvimbo dzinochinja nekukurumidza - kuwanikwa kwezvinovaka muviri kunogona kuwedzera kana kudzikira kamwe kamwe, mamiriro ekushushikana anogona kuitika kamwe kamwe, uye mabhakitiriya anofanira kupindura zvinobudirira kuti ararame. Imwe pfungwa huru inotsanangura kuti mabhakitiriya anoronga sei kuratidzwa kwemajini ndeye operon. Maoperons anobvumira majini akawanda ane mabasa akafanana kuti adzorwe sechikamu chimwe chete, zvichibvumira mabhakitiriya kuchengetedza simba uye kukurumidzisa mhinduro dzinochinjika.
Kunzwisisa Mashandiro
Operon iyuniti inoshanda yeDNA mumabhakitiriya inoumbwa neboka remajini akaumbwa ari muchikamu chimwe chete uye anoratidzwa pamwe chete pasi pekudzorwa kwechinhu chinodzora chakafanana. Kazhinji, majini ari muoperon anogadzira polycistronic mRNA imwe chete—zvichireva kuti molekyuru imwe chete yemRNA inotakura ruzivo rwekushandura mapuroteni akawanda panguva imwe chete. Izvi zvakasiyana nezvipenyu zvakawanda zve eukaryotic, izvo zvinowanzogadzira monocistronic mRNA (mRNA imwe chete yepuroteni imwe chete).
Pfungwa yemaoperon yakatanga kufarirwa naFrançois Jacob naJacques Monod kuburikidza nezvidzidzo zveEscherichia coli (E. coli), kunyanya lac operon, iyo inodzora kushandiswa kwelactose. Tsvagiridzo yavo yakaratidza kuti mabhakitiriya anogona kudzora kugadzirwa kwemajini zvichienderana nekuwanikwa kwesubstrate, uye kuti nzira iyi inosanganisira kudyidzana kwemapuroteni anodzora neDNA panzvimbo dzakatarwa.
Zvikamu Zvikuru zveOperon
Operon inowanzova nezvinhu zvakakosha zvakati wandei:
1. Mutsigiri
Chinosimudzira (promoter) iDNA sequence apo RNA polymerase inosungana kuti itange kunyorwa. Simba rechinosimudzira (kuti RNA polymerase inosungana zviri nyore sei) rinokanganisa mwero wekunyorwa.
2. Mushandi
Mushandisi chikamu cheDNA chinoshanda se "switch" nekuti ndipo panonamatira mapuroteni anotonga, akadai seanodzvinyirira. Kana mushandisi akasunga kumushandisi, kunyorwa kwechinyorwa kunowanzo rambidzwa.
3. Majini emuviri
Aya majini anonyora mapuroteni anoshanda, semuenzaniso maenzayimu ekugadzirisa kugaya kwechinhu, mapuroteni ekutakura membrane, kana zvikamu zvebiosynthesis.
4. Majini emuviri (anowanzo kuwanikwa kunze kwe operon)
Majini anotonga anochengetedza mapuroteni anotonga akadai seanodzvinyirira kana kuti activators. Zvigadzirwa zvemajini zvinotonga zvinogona kubatana nevanoshandisa kana dzimwe nzvimbo dziri paDNA kuti zvidzore kunyorwa kwezvinyorwa.
Kuwedzera kune zvikamu zvikuru zvataurwa pamusoro apa, mamwe maoperon anewo nzvimbo dzinobatanidza ma activator, ma transcription terminators, nezvimwe zvinhu zvinovandudza kutonga kwekutaura.
Sei maoperon achibatsira mabhakitiriya?
MaOperons anopa mabhenefiti akawanda ekugadzirisa:
– Kubatana kwekutaura: Majini anobatanidzwa munzira imwe chete yekuchinja kwemuviri anogona kuratidzwa pamwe chete, kuitira kuti pasave nepuroteni inogadzirwa "pasina" pasina mumwe wayo.
– Kushanda zvakanaka kwesimba: Kugadzira mapuroteni kunoda zvinhu zvakawanda. Nemaoperon, mabhakitiriya anodzivirira kutambisa simba kana mamiriro ekunze asingatsigire kushandiswa kwenzira iyoyo.
– Kukurumidza kupindura: Nekuti majini anodzorwa sechikamu chimwe chete, shanduko diki mukutonga (semuenzaniso, repressor binding) dzinogona kushandura kuratidzwa kwemajini akati wandei panguva imwe chete.
Maitiro Ekutonga: Masisitimu Ekukurudzira uye Ekudzvinyirira
Kazhinji, mutemo we operon unogona kukamurwa kuita zvikamu zviviri zvakakura zvichienderana nepfungwa dzawo dzekudzora: ma operon anoburitswa uye ma operon anodzorwa.
1. MaOperons Anogona Kupindurwa: Muenzaniso weLac Opera
Lac operon iri muE. coli inodzora kuputsika kwelactose. Majini ayo makuru ndeaya lacZ, lacCY, uye lacA:
- lacZ inoburitsa β-galactosidase iyo inopwanya lactose,
- lacY inoburitsa permease inobatsira kuisa lactose musero,
- lacA inoburitsa transacetylase (basa rekuwedzera).
Kana pasina lactose, puroteni inodzvinyirira (chigadzirwa chegene relacI) inosunga kune anoshanda, ichivhara RNA polymerase uye zvichikonzera kusaita kana kuti kuderera kwe transcription. Kana lactose iripo, imwe yelactose inoshandurwa kuita allolactose (inducer), iyo inosunga kune anodzvinyirira. Kusunga uku kunochinja chimiro chemudzoreredzi, zvichiita kuti ibve kune anoshanda. Nekuda kweizvozvo, RNA polymerase inogona kutevedzera majini elac, uye mabhakitiriya anotanga kugadzira ma enzymes anoparadzanisa lactose.
Lac operon inoratidzawo kurongeka kwakaomarara kuburikidza nekudzvinyirirwa kwecatabolite. Kana glucose (simba rinodiwa) iripo, huwandu hwe cAMP hunoderera, zvichidzivirira kuumbwa kwakanaka kweCAP-cAMP complex. Pasina activator iyi, kunyangwe paine lactose, kuburitswa kwe lac operon hakuna kunaka. Saka, mabhakitiriya anonyanya kukoshesa glucose kupfuura kushandiswa kwe lactose.
2. MaOperons Anodzorwa: Muenzaniso weTRP Opera
Trp operon inotonga biosynthesis yeamino acid tryptophan. Kusiyana nelac operon, trp operon inowanzo shanda kana tryptophan yakaderera, sezvo sero richida kuigadzira. Kana huwandu hwetryptophan hwakwira, tryptophan inoshanda se corepressor: inosunga kune trp repressor, ichibvumira kugona kwe repressor kusunga kune operator, nokudaro ichimisa kunyorwa kwemazwi.
Pfungwa yacho iri nyore: kana tryptophan yakawanda, haidi simba kuti igadziriswe; operon inodzimwa.
Mutemo Wekuwedzera: Kuderedza Kupisa
Mune mamwe maoperon, kusanganisira trp operon, pane imwe nzira inonzi attenuation. Iyi nzira inoenderana nekubatana kwakasimba pakati pekunyora nekushandura mubhakitiriya (zvose zvinogona kuitika panguva imwe chete). Mu trp operon, "leader" sequence inogona kuumba chimiro che hairpin pa mRNA. Iyi nzira inogona kushanda senzira yekutanga yekugumisa kunyora.
Kana tryptophan yakakwira, ribosome inofamba nekukurumidza kupfuura nzvimbo inotungamira, zvichiita kuti hairpin terminator iumbwe, uye transcription inomira gene risati ranyorwa zvizere. Kana tryptophan yaderera, ribosome inomira pa tryptophan codon, ichidzivirira hairpin terminator kuti isaumbwe uye ichibvumira transcription kuenderera mberi. Nenzira iyi, sero rinowana simba rakatsetseka pamusoro pehuwandu hwe tryptophan huripo.
Operations neBroader Gene Regulatory Network
Kunyange zvazvo pfungwa ye operon ichiita seyakareruka, kutonga kwemajini ebhakitiriya inetwork yakaoma. Ma operon mazhinji haatongwi nechinhu chimwe chete chinodzvinyirira, asi nevanotonga vakawanda, kusanganisira vanotanga kushanda, vanonzwa zvakatipoteredza, uye masisitimu maviri ane zvikamu zvinosanganisira mapuroteni kinases uye vanotonga mhinduro. Masisitimu aya anobvumira mabhakitiriya kuti ajairane ne pH, tembiricha, kumanikidzwa kwe osmotic, kuwanikwa kwe nitrogen, zvinhu zvine chepfu, uye zviratidzo zvinobva kune mamwe ma virus.
Pamusoro pezvo, mabhakitiriya anogona kushandura mukana wekuwana DNA kuburikidza nemapuroteni anosunga nucleoid uye kushandisa maRNA madiki anopindira (sRNAs) kudzivirira kana kusimudzira kushandurwa kwema mRNA anotarisirwa. Kunyange zvakadaro, ma operon achiri hwaro hwakakosha hwekuronga majini anoshanda kuita imwe chete.
Kukosha kweVashandi muBiotechnology neHutano
Kunzwisisa maoperon kwakakosha mu biotechnology. Masisitimu mazhinji ekugadzira majini murabhoritari anoshandisa ma promoter nema operator akagadziriswa kubva kuma bacterial operon, akadai se inducible lac-based system yekugadzira mapuroteni anobatana. Mukurapa, kudzorwa kweoperon kwakakoshawo pakurwisa hutachiona hwebhakitiriya—mamwe majini ekudzivirira hutachiona uye ma antibiotic anodzorwa ne operon kuti ashande nekukurumidza kana mabhakitiriya ari mukati memunhu kana kuti akasangana nemushonga.
Uyezve, kudzidza nezvemaoperon kunobatsira vaongorori kunzwisisa kuti mabhakitiriya anoshanduka sei nekubatanidza majini anoshanda pamwe chete. Mapoka emajini akarongwa kuita maoperon anowanzo famba nekutamiswa kwemajini akatwasuka, zvichibvumira kugona kutsva kwemetabolism kubuda nekukurumidza muhuwandu hwemabhakitiriya.
Mhedziso
Maoperoni inzira yakasiyana uye inoshanda yekudzora majini mumabhakitiriya, zvichibvumira majini akawanda kuratidzwa pamwe chete pasi pekudzora kumwe chete. Kuburikidza nezvikamu zvakaita sezvinokurudzira, maoperator, majini echimiro, uye mapuroteni anotonga, mabhakitiriya anogona kupindura kuchinjo dzezvakatipoteredza nekukurumidza uye zvine simba rakawanda. Maoperoni elac netrp anoratidza maitiro maviri makuru ekudzora - kupinza nekudzora - ayo anonatswa nemaitiro ekuwedzera akadai sekudzora kwecatabolite nekudzikamisa. Kunzwisisa maoperoni hakungopi chete kunzwisisa kwakakosha kwebhakitiriya molecular biology asiwo kunopa hwaro hunokosha hwekushandiswa kwebiotechnology, kutsvagurudza majini, uye nzira dzekurapa zvirwere zvinotapukira.
Kana muchida, ndinogona kuwedzera mufananidzo wezvikamu zveoperon, tafura yekuenzanisa yelac vs trp, kana bhuku remabhuku nemajenari kuti ndisimbise chinyorwa ichi.
