Qhov Tseem Ceeb - DNA Polymerase 1 vs 2 vs 3
DNA polymerase yog ib qho tshwj xeeb clade ntawm enzymes uas koom nrog DNA replication ntawm cov kab mob nyob. Cov ntaub ntawv caj ces yog dhau los ntawm ib tiam mus rau tiam tom ntej vim muaj cov enzyme no. Muaj ntau hom DNA polymerase enzyme pom nyob rau hauv eukaryotes thiab prokaryotes. DNA polymerase 1, 2 thiab 3 tsuas yog pom nyob rau hauv cov kab mob prokaryotic, thiab lawv ua lub luag haujlwm sib txawv hauv DNA replication. Qhov sib txawv tseem ceeb ntawm DNA polymerase 1 2 thiab 3 feem ntau yog nyob ntawm lub luag haujlwm tseem ceeb ntawm txhua enzyme. DNA polymerase 3 yog lub ntsiab enzyme uas catalyzes DNA synthesis, thaum DNA polymerase 1 thiab 2 koom nrog hauv DNA kho thiab proofreading.
YDNA Polymerase yog dab tsi?
DNA duplication yog ib qho yuav tsum dhau cov ntaub ntawv caj ces ntawm niam txiv mus rau cov xeeb ntxwv. Qhov no yog txhawb los ntawm ib qho tshwj xeeb enzyme hu ua DNA polymerase. DNA polymerase tuaj yeem txhais tau tias yog ib qho ubiquitous enzyme uas catalyzes cov synthesis ntawm DNA ntxiv rau cov DNA uas twb muaj lawm hauv cov hlwb nyob. Nws tau pom thawj zaug hauv E coli los ntawm Arthur Kornberg hauv xyoo 1955. DNA replication thiab txij nkawm feem ntau yog tswj hwm los ntawm DNA polymerases hauv lub cell. Kev tshawb pom ntawm DNA polymerases tau pab ntau cov txheej txheem ntawm molecular biology. Nws yog cov enzyme uas yuav tsum tau los tsim cov DNA tshiab zoo ib yam li thawj DNA ntawm cov kab mob los ntawm nucleotides thaum lub sij hawm ntau yam kev lom neeg molecular xws li PCR, gene cloning, gene sequencing, disease diagnosis, gene therapy, polymorphism analysis, etc.
DNA polymerases muaj nyob hauv ntau hom sib txawv ntawm cov duab thiab qhov loj me. Lawv nyob rau ntau tsev neeg: A, B, C, D, X, Y thiab RT. Prokaryotic DNA polymerases tau muab faib ua tsib pawg xws li, DNA polymerase 1, DNA polymerase 2, DNA polymerase 3, DNA polymerase 4 thiab DNA polymerase 5. Eukaryotic kab mob muaj kwv yees li kaum tsib yam DNA polymerases uas yog polymerase β, λ, σ, μ, α, δ, ε, η, ι, κ, Rev1, ζ, γ, θ thiab ν.
Daim duab 01: DNA polymerase
Thaum muab cov DNA tshiab los ntawm DNA polymerase, nws pib los ntawm 3' kawg thiab coj cov synthesis ntawm 5' kawg los ntawm kev ntxiv nucleotides ib zaug, ntxiv rau cov qauv DNA. DNA polymerase xav tau ib tug preexisting 3 'OH pab pawg neeg los pib cov saw synthesis thiab yog yooj yim los ntawm cov me me DNA los yog RNA fragment hu ua primer. DNA polymerase nyeem cov qauv DNA thiab txav los ntawm 3' kawg mus rau 5' kawg, ua ib qho tshiab 5'-3' DNA strand.
DNA Polymerase 1 yog dab tsi?
DNA polymerase 1 (Pol 1) yog ib qho enzyme pom nyob rau hauv prokaryotes uas pab nyob rau hauv cov kab mob DNA replication. Nws yog thawj hom DNA polymerase tshawb pom los ntawm Arthur Kornberg hauv xyoo 1956. Qhov enzyme no muaj nyob rau hauv tag nrho cov kab mob prokaryotic. Pol 1 yog encoded los ntawm cov noob polA thiab yog tsim los ntawm 928 amino acids. Nws muaj 5' rau 3' exonuclease kev ua; Yog li, nws yog nrov raws li DNA kho enzyme es tsis yog DNA replicating enzyme. Nws kuj tseem muaj peev xwm ua kom muaj ntau yam polymerizations ua ntej tso cov qauv DNA, thiab txuas Okazaki fragments ua ke los ntawm kev sau cov DNA tshiab, thiab tshem tawm RNA primers.
Pol 1 cais los ntawm E Coli tau siv dav hauv cov ntawv thov molecular. Txawm li cas los xij, ib zaug Taq Polymerase tau tshawb pom, nws hloov E Coli Pol 1 hauv PCR thev naus laus zis. Taq polymerase yog hom thermostable DNA polymerase uas yog Pol 1.
Daim duab 02: DNA Polymerase 1
DNA Polymerase 2 yog dab tsi?
DNA polymerase 2 (Pol 2) yog ib qho enzyme prokaryotic uas catalyzes DNA replication. Nws belongs rau tsev neeg polymerase B thiab yog encoded los ntawm gen polB. Nws tau pom thawj zaug los ntawm E Coli los ntawm Thomas Kornberg hauv xyoo 1970. Pol 2 yog cov protein globular muaj li ntawm 783 amino acids. Nws muaj ob qho tib si 3' rau 5' exonuclease kev ua thiab 5' rau 3' polymerase kev ua haujlwm. Nws cuam tshuam nrog DNA polymerase 3 enzymes kom muaj kev ncaj ncees thiab kev ua tiav ntawm DNA replication. Pol 2 kuj muaj peev xwm ua pov thawj cov DNA tshiab uas tau tsim los kom raug.
Daim duab 03: DNA Polymerase 2
DNA Polymerase 3 yog dab tsi?
DNA polymerase 3 (Pol 3) yog lub ntsiab enzyme uas catalyzes DNA replication hauv prokaryotes. Nws belongs rau tsev neeg C polymerase thiab yog encoded los ntawm cov noob polC. Nws tau tshawb pom los ntawm Thomas Kornberg hauv xyoo 1970. Pol 3 yog ib feem ntawm kev rov ua dua rab rawg thiab tuaj yeem ntxiv 1000 nucleotides ib ob rau cov tshiab polymerizing DNA strand.
Pol 3 yog ib qho holoenzyme tsim los ntawm kaum cov protein sib txawv thiab muaj peb lub cev ua haujlwm xws li α, ε thiab θ. Peb lub luag haujlwm molecules ntawm Pol 3 yog cais lub luag haujlwm rau peb qhov kev ua ntawm enzyme. Lub α subunit tswj cov polymerization ntawm DNA thaum lub ε tswj cov exonuclease proofreading kev ua ntawm pol 3 enzyme. Lub θ subunit pab lub ε subunit rau proofreading.
Daim duab 04: Subunits ntawm DNA Polymerase 3
Dab tsi yog qhov txawv ntawm DNA Polymerase 1 thiab 2 thiab 3?
DNA Polymerase 1 vs 2 vs 3 |
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| Polymerase 1 | Polymerase 1 yog tsim los ntawm 928 amino acids. |
| YPolymerase 2 | Polymerase 2 yog tsim los ntawm 783 amino acids. |
| YPolymerase 3 | Polymerase 3 yog ib qho holoenzyme uas muaj kaum cov proteins uas tau npaj ua peb lub luag haujlwm subunits. |
| Polymerase 1 | Polymerase 1 belongs rau tsev neeg polymerase A. |
| YPolymerase 2 | Polymerase 2 belongs rau tsev neeg polymerase B. |
| YPolymerase 3 | Polymerase 3 belongs rau tsev neeg polymerase C. |
| Lub luag haujlwm tseem ceeb | |
| Polymerase 1 | Qhov no yog lub luag haujlwm kho DNA thiab tshem tawm RNA primers. |
| YPolymerase 2 | Qhov no yog lub luag haujlwm rau kev lees paub, kev ncaj ncees, thiab kev ua tiav ntawm DNA tsim tshiab |
| YPolymerase 3 | Qhov no yog lub luag haujlwm rau DNA polymerization |
Summary – DNA Polymerase 1 vs 2 vs 3
DNA polymerase yog ib qho tseem ceeb enzyme chav kawm pom nyob rau hauv tag nrho cov kab mob nyob. Lub luag haujlwm tseem ceeb ntawm DNA polymerase yog DNA replication. Nws muaj peev xwm sib sau ua ke nucleotides thiab tsim cov DNA tshiab ntxiv rau DNA uas twb muaj lawm. Cov enzyme no muaj nyob rau hauv ntau hom sib txawv ntawm cov duab thiab loj. DNA polymerase 1, 2 thiab 3 yog prokaryotic DNA polymerases koom nrog hauv DNA replication. Pol 1 catalyzes kho cov DNA puas. Pol 2 catalyzes fidelity thiab processivity ntawm DNA replication. Pol 3 catalyzes 5' rau 3' DNA polymerization.
