Yintoni na reduplication-DNA? Inkqubo ye DNA ukuphindaphindeka

Kwemolekyuli DNA - use kubume chromosome. Enye chromosome iqulethe molecule elilodwa eliquka imisonto emibini. Reduplication ye DNA - na ukudluliselwa kolwazi emva kokuba self-lokwanda imisonto ukusuka molecule omnye komnye. Kuyinto sizalwa zombini DNA kunye RNA. Eli nqaku lixoxa inkqubo ukuphindaphindeka DNA.

ulwazi jikelele kunye neentlobo DNA yokuqaphela

Yinto eyaziwayo ukuba vulu ecikizekileyo kwi molecule. Noko ke, xa inkqubo ye DNA phindana luqala, bona dispiralized, ngoko amanyathelo ecaleni, yaye ikopi entsha ngalinye kuhlelwe. Lwakugqitywa kukho iimolekyuli ezimbini twatse ngokupheleleyo, iyileyo kukho umzali ephethe intsontelo nomntwana. Le njini kuthiwa semi-ngendeb '. iimolekyuli DNA namhlanje bachukumiseka, ngoxa a centromere enye, yaye ekugqibeleni diverge kuphela xa le nkqubo division centromere iqala.

I olunye uhlobo kuthiwa yokuqaphela reparative. Yena, ngokungafaniyo ezidlulileyo, sinxulumana nayiphi iseli inqanaba, kodwa iqala kuthe umonakalo DNA. Ukuba ngaba kakhulu iintlobo ngeentlobo indalo, iseli ekugqibeleni afe. Noko ke, ukuba umonakalo yeyobulali, ngoko unako ukubuyisela kubo. Kuxhomekeka ngxaki ukuze zibuyiselwe okanye kwahlula imisonto emibini ye DNA ngexesha elinye. Oku, njengokuba kubhaliwe kuthiwa, kuyondelelaniswe nezingacwangciselwanga akuthethi kuthatha ixesha elide yaye ayifuni amandla amaninzi.
Kodwa xa kukho reduplication le DNA, ngoko wachitha amandla amaninzi, izinto, wolula ubude iwotshi yayo.
Reduplication wahlulwe ezintathu:

• esuthwini;
• zobude;
• avalwe.

Makhe sihlolisise ukulandelelana DNA ukuphindaphindeka.

yokuqalisa

In DNA yabantu - emashumini ambalwa ezigidi ngababini isiseko (izilwanyana zingaba kuphela elinamanci anesithoba). DNA reduplication iqala kwiindawo ezininzi umxokelelwane ngenxa yezi zizathu zilandelayo. Ehlabathini ngexesha elifanayo RNA kwenzeka ukhutshelo, kodwa Yindibanisela iDNA liyanqunyanyiswa kwezinye iindawo ezikhethiweyo. Ngoko ke, inkqubo enjalo phambi kokuba isixa esaneleyo iziyobisi oluhlala xa kukho icytoplasm yeseli ukwenzela ukuxhasa ibinzana gene kunye nomsebenzi kweeseli yaphukile na. Ngenxa yoku, inkqubo kufuneka zenzeke ngokukhawuleza kangangoko kunokwenzeka. Kusasazwa ebudeni beli xesha wenziwe, kunye noshicilelo olo kuqhutywa. Uphononongo lubonise ukuba DNA reduplication kwenzeka kanye eziliqela amanqaku amawaka - kwiindawo ezincinane ulandelelwano nucleotide ethile. Bona uncediswa iiproteni umqalisi okhethekileyo, nto leyo ke ibhangayo ngamanye enzayim ye DNA ukuphindaphindeka.

Isiqwenga DNA leyo kuhlelwe ubizwa ngokuba replicon. Iqala ukususela ekuqaleni luze luphele xa enzyme uphelisa ukuphindaphindeka. Replicon le izimele, kwaye ukhupha kwakhona yonke inkqubo software yayo.
Le nkqubo ukuqala kuzo zonke iindawo ngaxeshanye, kwindawo ethile luqala ngaphambili; ethile - kamva; Kuthatha indawo elinye okanye kumacala amabini esahlukileyo. Iziganeko ezenzeka kulo umyalelo ilandelayo xa umfanekiso:

• neefolokhwe ukuphindaphindeka;
• RNA primer.

ukuphindaphindeka fork

Le nxalenye uveza inkqubo apho kwi ngemisonto kobonelelo ukuba kuhlelwe DNA kwayo deoxyribonucleic. Imigudu ngaloo ndlela zenze ekuthiwa Ngeso ukuphindaphindeka. Le nkqubo kwakhokelwa iqela lamanyathelo:

• ukumkhulula evela ngokunxulumene histones kwi nucleosome - enzayim ezifana kwesipirithi DNA phindana, acetylation, kunye phosphorylation ukuvelisa abasabela yemichiza nesiphumo iiproteni ingazehlela zabo ezintle lula kokukhululwa kwabo;
• despiralization - is imicu, nto leyo eyimfuneko ukuze kukhululwe ngakumbi imisonto;
• phula imixokelelwane hydrogen phakathi imicu DNA;
• divergence yabo kumacala ahlukeneyo kwemolekyuli;
• nitrogen ziyenzeka usebenzisa iiproteni SSB.

RNA primer

Yolungelelwaniso othatha enzyme ebizwa DNA polymerase. Noko ke, ukuqala okukokwakhe akakwazi, ngoko wenze ezinye enzyme - le polymerase RNA, ekwabizwa ngokuba kwenziwa RNA. Bona kuhlelwe xa imisonto engumzekelo deoxyribonucleic kwi umgaqo complementarity. Ngoko ke, ukuqaliswa RNA Yindibanisela emancamini omabini, kwenziwa ezimbini akatyeka baziqhawule imicu DNA.

zobude

Eli thuba kuqala ukongeza nucleotide kunye 3 'ekupheleni RNA-primer, nto leyo uthwele DNA polymerase senditshilo. Anamathela ukuba yesibini yokuqala, nucleotide wesithathu, njalo-njalo. intambo base New oxhulumene kwi ikhonkco umzali ngeentambo hydrogen. Ekukholelwa ukuba Yindibanisela ntambo kwi-5 '- 3'.
Apho kwenzeka ecaleni ifolokhwe phindana, loo kuyondelelaniswe lwenzeka ngokuqhubekekayo yaye kwangaxeshanye alongezi. Ngoko ke, lo ngomsonto ubizwa ngokuba esa okanye phambili. Yena RNA primer ayisa abembumbile.

Noko ke, phezu mngxilo icala umzali DNA nucleotides gqolo ukuzibandakanya primer RNA, yaye nomxokelelwane ideoxyribonucleic ukuba kuhlelwe kwelinye icala ukusuka ifolokhwe ukuphindaphindeka. Kulo mzekelo, ibizwa ngokuba ezilibazisekileyo okanye ningatyhafi.

Kwi kwanelo kan- kuyondelelaniswe kwenzeka iziqwenga, apho omnye isiphelo inxalenye njini iqala kwi kwenye indawo kufuphi ekusebenziseni loo RNA primer efanayo. Ngoko ke, kukho ezimbini yalityaziswa chain Isiqwenga ezihlanganiswe DNA kunye RNA. Bebizwa Okazaki iziqwenga.

Ke konke iyaphindwa. Emva koko spliced enye Ekuveleni kweleli, hydrogen ndiziqhawule unxibelelwano msonto emacaleni, ehamba nomxokelelwane elide kule kan- kuhlelwe zilandelayo Isiqwenga RNA primer, ebezikuyo - Okazaki ukuqhekeka. Emva koko, xa RNA yalityaziswa-Strand kwenziwa luyatshatyalaliswa ize amaqhekeza DNA zihlangene zibe omnye. Ngoko le wesekethe yenzeka ngexesha elinye;

• ukuyilwa primer entsha RNA;
• Yindibanisela Okazaki iziqwenga;
• ukutshatyalaliswa kwenziwa RNA;
• uhlangane kwisekethi enye.

Ukuphelisa

Le nkqubo iqhubeka nje ezimbini musa ukuhlangabezana nefolokhwe phindana, okanye omnye wabo angeza esiphelweni kwemolekyuli. Emva kwentlanganiso, neefolokhwe DNA intombi imisonto aba yi enzyme. Kwimeko, ukuba plug isusiwe ekuyeni ekupheleni molecule, DNA reduplication kosuku usebenzisa enzyme ezizodwa.

ukulungiswa

Kule nkqubo, indima ebalulekileyo yabelwa kulawulo (okanye ukulungiswa) of ukuphindaphindeka. Ukubeka ezwi ifumana zonke iintlobo ezine nucleotides, kwaye Uphenyo unekhodi DNA polymerase ukhetha abo olufunekayo.

Le nucleotide wanqwenela ukuba abe nako ukwenza iibhondi hydrogen kwakunye nucleotide efanayo kwi mngxilo DNA template. Ngaphezu koko, phakathi backbone iswekile-phosphate kufuneka kumgama othile rhoqo ehambelana kumakhonkco ezithathu iziseko ezibini. Ukuba nucleotide akwenziwa ngokwezi mfuno, udibaniso akuyi kwenzeka.
Control ikhutshwa phandle phambi kokuba ezifakwe wesiphaluka phambi kokuba nucleotide olulandelayo. Emva koko, lo uqhagamshelwano saharofosfata kuntlahlahlungulu.

akukho lula ukumisela mutational

Indlela ye DNA phindana, nangona ipesenti ephezulu okuchaneka kusoloko yokuphazamiseka kwayo, leyo ibizwa ngokuba uninzi "zofuzo sofuzo." Malunga ngababini isiseko iwaka, kukho enye impazamo ukuba konvariantnaya ngokuba reduplication.

Kuyenzeka ngenxa yezizathu ezahlukeneyo. Ngokomzekelo, xa zoqhaphelo aphezulu okanye asezantsi kakhulu nucleotides deamination of cytosine, phambi mutagens kwi Yindibanisela zombini. Kwezinye iimeko, le zolahlekiso ukulungiswa kweenkqubo wokulungisa kwezinye ulungiso kube nzima.

Ukuba umonakalo abachaphazelekayo isithuba ubuthongo, imposiso akayi zinganeziphumo ezibi xa kukho inkqubo ukuphindaphindeka DNA. ulandelelwano Nucleotide of isakhi kunokwenzeka sisiphoso ukukhwela. Ngoko ke akunjalo, yaye isiphumo ukumbombozela kunokuba ibe kukufa esiseleni, yaye ukufa yonke eziphilayo. Kufuneka kwakhona kukhunjulwa ukuba zofuzo zisekelwe isikrokro mutational, nto leyo eyenza i-gene echibini plasticity.

kwesipirithi

Ngexesha yokuqaphela, okanye ngoko nangoko emva kokuba kwenzeka imixokelelwane kwesipirithi. Kukholelwa ukuba le nkqubo kuyimfuneko ukuba umntu ukwenza zofuzo nokulawula gene nokubhalwa. Kule nkqubo bacterium DNA ukhonza ukhuseleko lalo ahlabayo enzyme.