Operon - Iyini?

была впервые предложена Ж. Моно и Ф. Жакобом. Operon model lokuqala ezihlongozwayo kaJ Monod F. uJakobe. Ngo-1961 bahlolisisa izinqubo ezihlobene ne ukuthuthukiswa E. coli amaseli. Ikakhulukazi safunda izindlela ukulawula izingxenye DNA ikhodi le ushukela ubisi (lactose).

incazelo

Monod noJakobe ezihlongozwayo isikimu zihlelwe ukulawula izigaba isakhi DNA. Ososayensi walinika igama "operon". схемы следующий. Umgomo we operation ye wesifunda kanje. Ukuhlelwa iqembu DNA ngamakhodi polypeptides ukuthi zisondelene kakhulu nomunye nokusebenza kulawulwa izakhi ezimbili. Eyokuqala isilawuli, kanti eyesibili - opharetha. Lesi sakamuva umelwe nucleotide ukulandelana ezakhelene izingxenye zesakhiwo elawulwa. Uma amaprotheni-compressor, yokunamathela kwayo ku-opharetha kuzovimba DNA umbhalo amayunithi uba umkhiqizo control. Lokhu, luyimfuneko kumiswa izithiyo steric ngoba RNA polymerase kwakwakhe ukuba ingxenye ethile umgqugquzeli. Lesi sakamuva kuyadingeka ukuqalisa umbhalo. Okunye ngentuthuko kuyoba icala, uma Umlawuli izenzo apoinduktor. Kulesi simo, uxhumano yayo opharetha kuzodala izimo umbhalo.

ngokucacile

последовательность ДНК, которая состоит из тесно сцепленных кодирующих участков, промотора и оператора. Operon - ukulandelana DNA yakhiwa kuhlobene esephepheni izifunda, umgqugquzeli kanye opharetha. Ukulawula isici ingase ibekwe eduze kwayo noma ibanga elithile kuwo. I-opharetha ngokuvamile phakathi amasayithi kwesakhiwo umgqugquzeli. Kukhona izinto ephansi yamangqamuzana, okuyinto zingalawulwa operon. в частности, эффекторы, которые являются индукторами или крепрессорами структурных участков, включенных в схему. Lokhu, ikakhulukazi, effectors okuyizinto inducers noma izigaba krepressorami kwesakhiwo kufakwe wesifunda.

ngezigaba

Unxenxwa ngaphakathi noma becindezela operon. зависит от характера влияния на их деятельность молекул-эффекторов. It kuncike uhlobo umthelela kumsebenzi kwabo effector molecule. Thina eyenga izakhiwo ke ihlanganyela repressor ngu ivimbela esibophezelayo ku-opharetha. Ngakho, kunezithiyo umbhalo izigaba kwesakhiwo. называется негативной. isiqondiso okunjalo kwezinkolo kubizwa ngokuthi operons ezimbi. Nokho, kungenzeka isakhiwo esibangelwa control omuhle. Kulokhu, lo effector sibopha a zokulawula amaprotheni molecule isebenze apoinduktor yayo. Joyina i-opharetha, lwenza umbhalo. Lezi zinhlobo ukulawula isinyathelo kanye nenhlonipho becindezela izakhiwo. Uma isiqondiso negative, effector, ayezosebenza njengabaqondisi corepressor, exhunywe nge repressor ngasebenzi kanye oyenza ke. Ngenxa yalokho, inzuzo yokugcina ikhono udokhe nge opharetha, ngaleyo ndlela ekuvimbeni umbhalo. Uma isilawuli omuhle, ngibopha kwenzeka nge apoinduktorom asebenzayo. Lesi sakhiwo ayikwazi exhunywe kwi-opharetha. Ngenxa yalokho, izingxenye zesakhiwo kungukuthi eloba.

okutholakele

Esikhathini ukulawula negative, ngaleyo ndlela effector ubopha repressor, okubangela inactivation noma ukusebenza. Ngakho, eyenga noma becindezela Ukushicelelwa operon. Endabeni isilawuli omuhle, uxhumano wenziwa apoinduktoru. Le nqubo ivumela noma amabhlogo umbhalo. Umphumela incike kundlela okuyinto ozuza apoinduktor lapho exhunywe effector.

Isakhiwo E.coli operon

Ngo E. coli kukhona isakhiwo kokuba ikhono lwalungabola-lactose. Kuhlanganisa umgqugquzeli kanye opharetha ezintathu ingxenye DNA kwesakhiwo. Coding gengalaktozidaza wadalula enzyme galaktozidpermeaza, tiogalaktozidtransatsetilaza. Ukuze ngamunye wabo isakhi sofuzo lalo. I operon ihlanganisa izingxenye Lac Z, Lac A, Lac Y. Umsuka buqonda gengalaktozidazu catalyzing lactose ukuba glucose ne-galactose. Lac Y baxhumana galaktozidpermeazoy. Lokhu enzyme inikeza ezokuthutha ushukela ezahlukene. Lac A buqonda tiogalaktozidtransatsetilazu. Nokho, indima yayo, akucaci e inqubo kokulahla ubisi noshukela. Ngokuvamile, wonke amaprotheni atholakala emangqamuzaneni Escherichia coli e trace amanani. Nokho, lapho esekhulile imvelo yayo, lapho ematheni carbon futhi umthombo wamandla izenzo lactose, ama-enzyme Bayanda izikhathi 1000.

zamagama constitutive

включает в себя структурный участок lac 1. Им кодируется белок-репрессор. operon lactose kufaka kwesakhiwo ingxenye Lac 1. okubhalwe repressor amaprotheni. In the state asebenzayo, it is a tetramer, kwakhiwa amakhophi amane ingxenye Lac 1 okuyinto - a polypeptide ehlanganisa a amino acid 360. Amaseli nezinguquko yilesi sakhi phezu zamagama amaprotheni constitutive okubhalwe Lac Z, Y no A. Kulokhu, lokhu kungenzeka uma engekho ukuguquka kwezakhi zofuzo kuphela repressor, kodwa esitatimendeni. Izinguquko ezinjalo, ngakho ihlale cis-evelele. Lokhu kungenxa yokuthi i-opharetha, uma kuqhathaniswa a repressor, zingathonywa yilabo kungenzeka umbhalo kuphela uma etholakala iseduze umgqugquzeli. Uma ekhona compounds cell olubangelwa, beze nge opharetha ukuncintisanela engqamuzaneni repressor.

inductors

Kungenzeka uxhumano ezahlukene. Lactose izenzo kokubili njengenhlangano inducer futhi njengoba substrate. Ngo amangqamuzana avamile futhi ngenxa yokuntuleka kwezinhlelo ezibanzi eyenga enzyme asalile umsebenzi zezakhi luhlinzeka ukuthi kungenzeka Ukungena lactose amanani amancane. Ngenxa yalokho we okhanda amanye amathuba ukuphendula lactose uguqulwe allolactose. Yena, uhlanganisa kuya repressor futhi kuphakamisa esisinqabela ixhumeke kumsindo opharetha. Lokhu kuvumela uhlelo polymerase RNA kuya-dock umgqugquzeli. Lokhu kuzoqala umbhalo Lac Z, A no Y. compounds esebenza kuphela njengoba inductors, IPTG futhi TMG zisetshenziselwa ukutadisha ukulawula operon-lactose.

izakhi isenzangakhona

ukuhlonza labo kubangelwa diauksiey. Ingqikithi zalesi simo wukuthi ukusetshenziswa kwe-lactose iqala kuphela ngemuva kokusebenzisa zonke glucose etholakala medium. Diauksiya - omunye zokubonisa catabolite ezingabekwa zokucindezelwa kwalabo bantu. Lo mphumela is kusukela 40s glucose ezaziwayo. ekhulwini elidlule leminyaka. Lubonakaliswa E. coli ukungakwazi catabolize carbohydrate ezahlukene khona glucose. Yena, uba umthombo kahle ukusetshenziswa amandla.

Mshini ngomphumela

Kungaba wokufunda Pastan futhi Perlman. Bathole izakhi ezimbili alotshwa operon lac-. небольшая молекула-эффектор – цАМФ (циклический аденозинмонофосфат) и белок-активатор катаболизма САР. Lena i-molecule effector encane - ekamu (eyindilinga adenosine monophosphate) kanye Activator amaprotheni catabolism ATS. Ngo eukaryotes, owokuqala izenzo ngokuthi umlamuleli hormone senzo. Kwatholakala ukuthi ukwengeza ekamu ukuba E. coli amaseli, ezikhulayo endaweni nokuba khona glucose, decelerates ijubane layo uma igijima, kodwa isuswe ezingabekwa zokucindezelwa kwalabo bantu catabolic. Lokhu, kubangela kungenzeka inkulumo ethi Lac-operon ebukhoneni ngesikhathi esisodwa ne-glucose ne-lactose. Ngemva kwesikhathi esithile bekulokhu lobudlelwano. Umsebenzi we zamagama enzyme ekamu kulomkhakhancane uvinjelwa glucose.

isiphetho

Ikhophi operon esilawulwa ezimbili - engemihle futhi omuhle. CAP-Camp eziyinkimbinkimbi lisita polymerase RNA ukuxhuma kwi-DNA isifanekiso ngaphambi ukucubungula. Okwamanje, ososayensi ziqala ephelele nucleotide uchungechunge esifundeni lelawula Lac-operon, lapho kukhona opharetha futhi umgqugquzeli. Ngaphezu kwalokho, ngo-1969, yena labelwa DNA isinqamu zalo ezihlanzekile equkethe Lac 1 umgqugquzeli futhi ngokugcwele opharetha ukulandelana, Lac Z kanye Lac Y. isinqamu Esifundweni kwatholakala ukuthi indima ebalulekile nokuxhumana amaprotheni multimeric nge-DNA fanele izakhiwo ziyalingana - palindrome . I-opharetha Lac-operon of abakhona yabo 26. Ngesikhathi esifanayo 14 kulo bayizinkulungwane ngokucacile ezahlukene. ngamaketanga ahlukene ukufunda efanayo kodwa kolunye uhlangothi. Palindrome zikhonjwe ingxenye umgqugquzeli nokusebenzisana isakhiwo kwekamu-CAP.