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DNA Replication (Prokaryotes and Eukaryotes) DNA Odgovor (Prokaryotes i eukariota)

The E. coli chromosome begins its DNA replication at a single origin of replication called, oriC and proceeds bidirectionally to a termination site located approximately halfway around the circular chromosome. U E. coli kromosom počne replikacija DNA na jednom podrijetlo replikacija zove, ORIĆ i prihod bidirectionally do raskida site se nalazi otprilike na pola puta oko kružne kromosom. In order for replication to proceed, the DNA strands of the double helix must be both unwound and separated. Kako bi za odgovor da nastavite, DNA strukturi od dvokrevetne Helix mora biti oba i odvojen odmotan. DNA replication is initiated when a protein encoded by the gene dnaA binds repetitive 9-mer sequences at the origin. Replikacija DNA je pokrenuo kada je protein kodirane od strane dnaA gena povezuje se ponavljaju 9-mer sekvence u izvora.

Subsequently, helicases specified by dnaB and inhibitory proteins encoded by dnaC bind repetitive 13-mer sequences. Nakon toga helicases Navedeni dnaB i inhibitory proteini kodirani by dnaC obvezujete se ponavljaju 13-mer sekvenci. As helicase progresses 5' to 3', dissociation of protein DnaC allows the helicase to unwind the DNA. Kao helicase napreduje 5 'to 3', dissociation of protein DnaC omogućuje helicase se odviti u DNA. The unwinding produces positive superhelical turns in the rest of the DNA, making it energetically favorable to continue unwinding the strands. The odmotavanje proizvodi pozitivne superhelical pretvara u ostatak od DNA, što je pogodnije da energično nastaviti odmotavanje u strukturi. To unwind the DNA, positive superhelical turns have to be removed by cutting the DNA and allowing it to relax or by introducing negative superhelical turns to compensate for the positive ones. Da odviti u DNA, pozitivnoj superhelical skreće moraju biti uklonjene od strane Rezanje DNA i dopuštajući da se opustiti ili uvođenjem negativne superhelical skreće na naknadu za one pozitivne. The introduction of negative superhelical turns requires energy and an enzyme called DNA gyrase (a topo-isomerase). Uvođenje negativne superhelical skreće zahtijeva energiju i jedan enzim pod nazivom DNA gyrase (topo-isomerase). DNA gyrase is an enzyme that can both remove positive supercoils or introduce negative supercoils into the DNA and thereby make strand separation energetically more favorable. DNA gyrase je enzim koji može i ukloniti supercoils pozitivnih ili negativnih supercoils uvesti u DNA i time čine nasukavanje razdvajanja energicno povoljnije.

Presumably the DNA gyrase binds ahead of the unwound DNA during replication. Vjerojatno je DNA gyrase ispred veže je odmotan DNA tijekom replikacije. Single-stranded binding proteins (SSBPs) act to temporarily stabilize the unwound state. Jednokrevetna nasukan obvezujuća proteina (SSBPs) djelovati na stabiliziranje, odmotan privremeno stanje. DNA replication begins with the synthesis of a 30 nucleotide long RNA primer by an RNA polymerase called primase (specified by dnaG). Replikacija DNA počinje s sinteza od 30 nukleotidne dugo RNA upaljač po jedan RNA polymerase zove primase (Navedeni dnaG). The helicase and primase subsequently form a complex enzyme system known as the primosome, which synthesizes primers after DNA synthesis begins. The helicase i primase naknadno formira kompleks enzim sustav poznat kao primosome, koji synthesizes početnice nakon DNA sinteza počinje. Two catalytic subunits of DNA polymeraseIII (PolC) associate with the templates and the 3' ends of the primers and begin to polymerize deoxyribonucleotides into DNA. Dva katalitička podjedinica DNA polymeraseIII (PolC) suradnik s predlošcima i 3 'krajevi su početnice i početi polymerize deoxyribonucleotides u DNA. DNA gyrase continues to remove positive supercoils and/or introduces negative supercoils ahead of the primosome that is opening the two strands of DNA. DNA gyrase i dalje pozitivno supercoils ukloniti i / ili uvodi negativne supercoils ispred primosome je da je otvaranje dva smjera DNA. At various intervals, the template signals the primase portion of the primosome to polymerize primer RNAs about 30 nucleotides long on only one template at the replication fork. U različitim intervalima, predložak signali u primase dio je primosome da polymerize upaljač RNA oko 30 nukleotidima dugo na samo jedan predložak na odgovor tanjura. DNA polymerase III polymerizes DNA 5' to 3' from each of the primers at the replication fork. DNA polymerase III polymerizes DNA 5 'to 3' iz svake od početnice na odgovor tanjura. One strands of DNA is polymerized toward the replication fork and continues to be elongated as the DNA unwinds further. Jedan strukturi DNA je polymerized prema replikacija tanjura i dalje biti izdužen kao DNA unwinds dalje.

The second strand of DNA is polymerized away from the replication fork. Druga obala DNA je polymerized daleko od preslika tanjura. As the DNA unwinds further, a new primer is synthesized away from the replication fork and the DNA polymerase synthesizes DNA from the last primer toward the previous RNA primer. Kao DNA unwinds dalje, novi udžbenik je umjetni daleko od tanjura i replikacija DNA polymerase synthesizes DNA iz prošle udžbenik prema prethodnom RNA fitilj. As the DNA polymerase reads the template strand, it selects complementary nucleotides for the nascent strand based on hydrogen bonding capability. Kao DNA polymerase reads predložak Strand, ona odabire komplementarnih nukleotidima za nascent nasukavanje na temelju vodika veza mogućnosti. The DNA synthesized toward the replication fork is synthesized in a continuous manner and is called the leading strand. The DNA umjetni ka replikacija tanjura je sintetizirana u neprekidnu način i zove vodeći obala. The opposite DNA strand is synthesized in a discontinuous manner away from the replication fork and is referred to as the lagging strand. U suprotnom obala DNA je sintetizirana u diskontinuiran način daleko od tanjura i odgovor je koji se navode kao lagging obala. The leading and lagging strands are synthesized halfway around the bacterial chromosome until they encounter the lagging and leading strands synthesized at the other replication fork. Vodeći i lagging strukturi su sintetizirana na pola puta oko bakterijski kromosom dok ne naiđete na lagging i vodeći strukturi umjetni na druge replikacija tanjura. The RNA-DNA fragments that initially constitute the lagging strand are known as Okazaki fragments, named after the scientist who discovered them. The RNA-DNA fragmenata koji u početku čine lagging nasukavanje poznati su kao Okazaki fragmenti, ime po znanstveniku koji je otkrio ih. The RNA primers are removed by a DNA repair enzyme called DNA polymerase I speci?ed by polA. The RNA početnice su uklonjeni sa popravka DNA enzim pod nazivom DNA polymerase I speci? Ed by Pola. It uses neighboring DNA as a primer and polymerizes DNA from it, displacing the RNA primer. Ona koristi susjedne DNA kao udžbenik i polymerizes iz DNA, RNA displacing je fitilj. A DNA ligase removes nicks in the DNA by connecting the fragments together. A DNA ligase uklanja nicks u DNA by povezuje fragmenti zajedno. Topoisomerase IV is required to separate the two daughter chromosomes. Topoizomeraza IV je dužan da se razdvoje dvije kćeri kromosoma.

DNA replication in eukaryotic chromosomes generally is initiated from many origin of replication sites. Replikacija DNA u eukaryotic kromosoma općenito je pokrenuo od mnogih podrijetlo replikacija sučelja. Replication forks proceed in both directions from these sites. Odgovor viljuške nastaviti u oba smjera od tih stranica. The sites that comprise yeast origins of replication are called autonomously replicating sequences (ARSs) and consist of two regions that bind a distinct set of proteins that destabilize the double helix. Web stranice koje obuhvaćaju kvasac podrijetlo replikacija se zovu autonomno Umnožava sekvence (ARSs) i sastoji se od dvije regije da svežemo jedan poseban set proteina da destabilizuju dvokrevetne Helix. In one region, conserved, repeating 11-mers bind a multiprotein complex called the origin recognition complex (ORC). U jednoj regiji, konzervirano, ponavlja 11-mers svežemo jedan multiprotein kompleksa naziva podrijetla prepoznavanje kompleksa (ORC). When proteins also bind the other region, the DNA bends by interaction of the proteins in the two regions. Kada proteina i obvezujući za druge regije, DNA interakcije od strane zavoja i proteini u dvije regije.

This distortion of the DNA promotes the separation of paired DNA strands at the origin and initiation of RNA primer synthesis. Ovo izobličenje od DNA promiče odvajanje paired DNA strukturi na podrijetlo i pokretanje prvog sinteza RNA. Enzymes similar to those involved in bacterial DNA replication are found in eukaryotes. Enzimi slične onima koji su uključeni u bakterijske replikacija DNA nalaze u eukariota. Numerous topoisomerases, helicases, and RNA polymerases have been found in eukaryotes. Brojni topoisomerases, helicases, i RNA polymerases nađeni su u eukariota. DNA topoisomerase II is involved in relieving positive supercoils in the DNA, whereas a helicase activity separates the two strands. DNA topoizomeraza II koji su uključeni u pozitivne olakšavanja supercoils u DNA, dok helicase activity dijeli na dva smjera. At least five different DNA polymerases have been found in eukaryotic cells. Najmanje pet različitih DNA polymerases nađeni su u eukaryotic stanice. The primase (DNA pola) synthesizes lagging strand DNA. The primase (DNA Pola) synthesizes lagging obala DNA. DNA pola catalyzes leading strand synthesis. DNA pola catalyzes vodeći nasukavanje sinteza. DNA pole and DNA polb are responsible for replacing the nucleotide gaps created when RNA primers are removed by endonucleases. Pole DNA i DNA polb su odgovorni za zamjenjujući nukleotidne praznine kreirana kada RNA početnice su uklonjeni od strane endonucleases. A DNA ligase repairs single stranded nicks (unconnected adjacent nucleotides) left in the DNA. A DNA ligase popravke single nasukan nicks (nepovezan susjedna nukleotidima) lijevo u DNA. DNA polg performs DNA replication in the mitochondria. DNA polg obavlja replikacija DNA u mitochondria. To complete replication of a linear chromosome, RNA primers at each end of the chromosome have to be removed and replaced by DNA. Za potpuni odgovor od linearnih kromosoma, RNA početnice na svakom kraju je kromosom moraju biti uklonjena i zamijenjena DNA. Although RNA primers can be removed by exonucleases, none of the usual DNA polymerases are able to replace the RNA without a DNA primer. Iako RNA početnice može biti uklonjena by exonucleases, nitko od uobičajenog DNA polymerases su mogli zamijeniti RNA bez DNA fitilj. An unusual type of DNA polymerase known as telomerase consists of protein and an RNA template that the protein portion copies repetitively into DNA in order to extend one strand of the telomere. Dogodila se neobična vrsta DNA polymerase poznat kao Telomeraza se sastoji od proteina i RNA template da protein dio kopije repetitively u DNA, kako bi produžili obala jedna od telomere. Thus, telomerase is responsible for maintaining the length of the chromosomes. Ovako, Telomeraza je odgovoran za održavanje dužini od kromosoma.