Usoro Ndekọ Ihe na Bayọlọji Molekụla
Nsụgharị bụ usoro dị mkpa na bayoloji molekul nke na-ejikọ ozi mkpụrụ ndụ ihe nketa dị na DNA na mmepụta nke molekul RNA. Site na ntụgharị, a na-atụgharị usoro nucleotide dị na DNA ka ọ bụrụ RNA, nke nwere ike ịrụ ọrụ dị ka ozi RNA (mRNA) maka njikọ protein, ma ọ bụ dị ka RNA ndị ọzọ na-arụ ọrụ dị ka rRNA na tRNA. Usoro a bụ akụkụ dị mkpa nke nkwenkwe etiti nke bayoloji: DNA → RNA → Protein. Ọ bụ ezie na ọ nwere ike ịda ụda dị mfe, ntụgharị gụnyere usoro usoro ahaziri ahazi, enzymes dị iche iche, na nhazi siri ike ka mkpụrụ ndụ wee nwee ike igosipụta mkpụrụ ndụ ihe nketa kpọmkwem dịka ọ dị mkpa.
Echiche ndị bụ isi nke ntụgharị okwu
N'ihe gbasara ntụgharị okwu, naanị otu n'ime eriri DNA ka a na-eji dị ka eriri template. Enzyme polymerase RNA na-agụ eriri template site na 3' ruo 5' ma na-emepụta RNA ọhụrụ n'akụkụ 5' ruo 3'. Usoro RNA nke si na ya pụta na-emekọ ihe na eriri template DNA, nke nwere nnukwu ọdịiche: RNA na-eji uracil isi (U) kama thymine (T). Ya mere, ọ bụrụ na A dị na DNA, U bụ akụkụ ntọala na RNA, ọ bụrụkwa na C dị, G bụ akụkụ ntọala (na nke ọzọ).
Ndekọ ihe nwere ike ime n'ụdị mkpụrụ ndụ ihe nketa dị iche iche. Mkpụrụ ndụ ihe nketa ndị na-enye protein koodu na-emepụta mRNA, ebe mkpụrụ ndụ ihe nketa ndị ọzọ nwere ike imepụta RNA na-abụghị nke na-enye koodu nke a na-asụgharịghị ka ọ bụrụ protein mana o nwere ọrụ nhazi na nhazi, dịka rRNA (ihe owuwu ribosomal), tRNA (ndị na-ebu amino acid), snRNA (nchịkọta), na ụdị miRNA/lncRNA dị iche iche nke na-achịkwa ngosipụta mkpụrụ ndụ ihe nketa.
Isi ihe dị iche na ihe dị iche n'etiti prokaryotes na eukaryotes
Na prokaryotes (dịka ọmụmaatụ, nje bacteria), usoro ntụgharị ihe dị mfe. N'ozuzu, e nwere otu RNA polymerase mbụ, nke na-enyere aka na sigma factor, nke na-amata onye na-akwalite ya. Ọzọkwa, n'ihi na nje bacteria enweghị nucleus, ntụgharị ihe na ntụgharị nwere ike ime n'otu oge n'ebe ndị dị nso.
N'ụzọ dị iche, na eukaryotes (dịka ọmụmaatụ, ụmụ mmadụ), ntụgharị ihe dị mgbagwoju anya karịa. Ọtụtụ polymerase RNA dị: RNA polymerase I (na-akọwapụta ụfọdụ rRNAs), RNA polymerase II (na-akọwapụta mRNAs na ụfọdụ snRNAs/miRNAs), na RNA polymerase III (na-akọwapụta tRNAs na 5S rRNAs). Ọzọkwa, a na-etinye DNA eukaryotic na chromatin, yabụ ịnweta mkpụrụ ndụ ihe nketa chọrọ iwu ndị ọzọ, gụnyere mgbanwe histone, nhazi chromatin, na ọtụtụ ihe ntụgharị ihe dị iche iche.
Nkebi nke 1: Mmalite nke ntụgharị okwu
Mmalite bụ ọkwa mbụ mgbe a na-achịkọta igwe ntụgharị okwu n'ebe kwesịrị ekwesị na DNA. Usoro a na-amalite site n'ịmata onye na-akwalite ya, usoro DNA kpọmkwem dị n'elu mkpụrụ ndụ ihe nketa nke na-ekpebi ebe mmalite nke ntụgharị okwu.
Mmalite na prokaryotes
N'ime nje bacteria, ihe ndị na-egosi na ha na-enyere RNA polymerase aka ịmata ihe ndị dị mkpa na-akwalite ihe dịka igbe Pribnow na igbe 35. Mgbe RNA polymerase jikọtara na onye na-akwalite ihe, "mgbagwoju anya mechiri emechi" na-etolite. DNA gbara ebe mmalite ahụ na-emepe nke ọma, na-emepụta "mgbagwoju anya mepere emepe," na-enye ohere ka RNA polymerase malite ịchịkọta nucleotides RNA mbụ.
Mmalite na eukaryotes
Na eukaryotes, mmalite gụnyere ọtụtụ protein. Na mkpụrụ ndụ ihe nketa nke RNA polymerase II dekọrọ, ndị na-akwalite ya na-enwekarị (ọ bụ ezie na ọ bụghị mgbe niile) nwere ihe ndị dị ka igbe TATA. Protein TATA-binding (TBP), akụkụ nke mgbagwoju anya TFIID, na-amata igbe TATA ma na-ewepụta ihe ndị ọzọ na-akọwapụta ihe (TFIIA, TFIIB, TFIIE, TFIIF, na TFIIH) yana RNA polymerase II. A na-akpọ mgbagwoju anya a mgbagwoju anya tupu mmalite.
TFIIH na-arụ ọrụ dị oke mkpa n'ihi na o nwere helicase (nkwụsị DNA) na ọrụ kinase, nke na-eme ka CTD (C-terminal domain) nke RNA polymerase II dị na phosphorylation. CTD phosphorylation na-enyere RNA polymerase II aka "ịhapụ" ya site na onye na-akwalite ya ma banye na usoro ogologo oge, ebe ọ na-enyekwa ikpo okwu maka protein nhazi RNA.
Nkebi nke 2: Ogologo ntụgharị okwu
Mgbe mmalite gasịrị, RNA polymerase na-agagharị n'akụkụ DNA template ma na-agbatị usoro RNA. A na-agbakwụnye nucleotides RNA (ATP, UTP, GTP, CTP) otu otu, ka ụzọ abụọ nke isi na-eme. N'oge ịgbatị, RNA polymerase na-emepụta afụ transcription ebe DNA na-akwụsịtụ nwa oge. N'azụ polymerase, DNA na-akwụsịtụ, ebe RNA e guzobere ọhụrụ na-apụ na mgbagwoju enzyme ahụ.
Ogologo ihe nwekwara obere usoro nyocha. Ọ bụrụ na nsogbu emee, RNA polymerase nwere ike ịkwụsịtụ ma dozie njehie ahụ site na ibelata njedebe na-ezighi ezi nke RNA, wee gaa n'ihu na mmepụta ya.
Na eukaryotes, a na-ejikarị ogologo oge na-esochi iwu ndị ọzọ, dịka ịkwụsịtụ RNA polymerase II nso onye na-akwalite ya. Nkwụsịtụ a dị mkpa maka nhazi mkpụrụ ndụ ihe nketa a haziri ahazi na njikere maka idegharị ngwa ngwa mgbe mkpụrụ ndụ ahụ natara akara pụrụ iche.
Nkebi nke 3: Nkwụsị nke ihe odide
Nkwụsị bụ usoro nke ịkwụsị ntụgharị na ntọhapụ nke RNA na RNA polymerase site na DNA.
Ọgwụ mgbochi na prokaryotes
E nwere usoro abụọ bụ́ isi:
1. Nkwụsị dị n'ime (nke na-adabereghị na rho): DNA nwere usoro nke na-emepụta RNA bara ọgaranya nke GC na-emepụta usoro ntụtụ ntutu, wee soro usoro U bara ọgaranya. Ntụtụ ntutu isi na-eme ka RNA polymerase kwụsị, njikọ RNA-DNA na-ebelata nke mere na mgbagwoju anya ahụ na-ekewapụ.
2. Nkwụsị nke dabere na Rho: Protein rho (helicase) na-arapara na RNA ma na-agagharị na ya ruo mgbe ọ ruru polymerase RNA nke kwụsịtụrụ, wee wepụta RNA ahụ na mgbagwoju anya nke transcription.
Nkwụsị na eukaryotes (RNA polymerase II)
N'ọtụtụ mkpụrụ ndụ ihe nketa, RNA polymerase nke Abụọ na-agafe akara polyadenylation (dịka ọmụmaatụ, AAUAAA na RNA) wee kewaa ya site na mgbagwoju nhazi. Mgbe e kewara ya, njedebe nwere ike ime site na ụdị "torpedo" (enzyme exonuclease na-emebi RNA fọdụrụ ma na-achụso polymerase) ma ọ bụ ụdị mgbanwe nhazi dị mgbagwoju anya. Nkwụsị na RNA polymerases nke I na nke III nwere usoro dị iche, nke akọwapụtara usoro.
Nhazi RNA na eukaryotes: site na pre-mRNA ruo mRNA tozuru okè
Isi ihe dị iche n'etiti prokaryotes na eukaryotes bụ na a ga-ahazi mRNA eukaryotic tupu atụgharịa ya. Nhazi a na-eme n'otu oge (yana ntụgharị) ma gụnye:
1. Mgbakwunye okpu 5': Mgbakwunye nke otu 7-methylguanosine na njedebe 5'. Mkpuchi ahụ na-echebe RNA pụọ na mbibi, na-enyere aka mbupụ na cytoplasm, ọ dịkwa mkpa maka mmalite ntụgharị asụsụ.
2. Ịkpakọ: Iwepụ introns na ịgbakọ exons site na spliceosome. Ịkpakọ ọzọ nwere ike imepụta ọtụtụ isoforms protein site na otu mkpụrụ ndụ ihe nketa, na-eme ka ụdị proteome dịkwuo elu.
3. Polyadenylation (ọdụ poly-A): Mgbakwunye ọdụ poly-A na njedebe nke 3'. Ọdụ a na-eme ka mRNA kwụsie ike, na-enyere aka mbupụ, ma na-emetụta arụmọrụ ntụgharị asụsụ.
A naghị atụgharị RNA a na-anaghị ahazi (pre-mRNA) n'ọtụtụ oge. Sistemụ njikwa mma nke mkpụrụ ndụ ahụ ga-ejigide ma ọ bụ mebie RNA nwere nkwarụ.
Iwu mgbanwe mkpụrụ ndụ ihe nketa: gịnị mere mkpụrụ ndụ ihe nketa niile anaghị arụ ọrụ oge niile?
Ndekọ ihe bụ isi ihe na-achịkwa ngosipụta mkpụrụ ndụ ihe nketa. Mkpụrụ ndụ na-achịkwa mkpụrụ ndụ ihe nketa ndị na-arụ ọrụ, otú e si dee ha nke ọma, na mgbe e kwesịrị ịkwụsị idekọ ihe. Iwu a na-enye mkpụrụ ndụ ohere ịzaghachi mgbanwe gburugburu ebe obibi, ihe mgbaàmà homonụ, nrụgide, ma ọ bụ mkpa mmepe.
Na prokaryotes, nhazi na-agụnyekarị operon, dịka lac operon, nke na-eme ka enzyme nke na-ekewa lactose rụọ ọrụ naanị mgbe lactose dị. Ihe mgbochi na ihe na-eme ka activator nwee ike igbochi ma ọ bụ mee ka RNA polymerase nweta ọrụ dịkwuo mma.
Na eukaryotes, nhazi dị mgbagwoju anya karịa. Ihe ndị dị ka ihe na-eme ka ihe dịkwuo mma na ihe na-eme ka ihe ghara ịdị jụụ nwere ike ịnọ n'ebe dị anya site na onye na-akwalite ya mana ha na-emetụta ọrụ ntụgharị site na mpịachi DNA na mmekọrịta protein. Ọzọkwa, ọnọdụ chromatin (dịka ọmụmaatụ, histone acetylation, nke na-eme ka DNA "mepee emepe") na-ekpebi nke ọma ma mkpụrụ ndụ ihe nketa ọ bụla dị na igwe ntụgharị.
Penutup
Usoro nke ntụgharị okwu bụ isi ihe dị mkpa n'otú e si egosipụta ozi mkpụrụ ndụ ihe nketa n'ime RNA, ma dị ka etiti maka njikọ protein na dị ka molekul ọrụ nke na-arụ ọrụ nchịkwa na nhazi. Usoro a na-eme site na usoro atọ bụ isi - mmalite, ogologo oge, na njedebe - yana mgbagwoju anya dị iche iche n'etiti prokaryotes na eukaryotes. Na eukaryotes, a na-ejikọta ntụgharị okwu nke ọma na nhazi RNA dị ka nhazi okpu 5', njikọta, na polyadenylation. N'ihi na ntụgharị okwu na-adaberekwa na iwu nchịkwa dị elu, nghọta nke usoro a dị oke mkpa n'ọtụtụ ubi, site na mkpụrụ ndụ ihe nketa na bayoteknọlọji ruo na ọgwụ molekul, gụnyere ịghọta ọrịa ndị metụtara nkwarụ ngosipụta mkpụrụ ndụ ihe nketa.
