DNA Polymerase vs RNA Polymerase
Cov no yog ob qhov sib txawv enzymes lub luag haujlwm rau kev ua haujlwm sib txawv uas tshwm sim hauv qib cellular. Feem ntau cov tsim ntawm DNA thiab RNA strands yog tswj los ntawm cov enzymes. Kab lus no npaj los tham txog qhov sib txawv tseem ceeb ntawm cov enzymes tseem ceeb no rau ntau cov txheej txheem ntawm kev txhawb nqa lub neej.
YDNA Polymerase
DNA polymerase enzyme pib nws txoj haujlwm thaum lub sijhawm rov ua dua ntawm DNA, ntawm kauj ruam ntawm kev teeb tsa cov nucleotides cuam tshuam los tsim hydrogen bonds ntawm cov khoom siv nitrogenous ntawm cov DNA uas twb muaj lawm thiab tshiab. Cov enzyme no ua haujlwm tau zoo tom qab DNA ob chav helix qauv yog dismantled los yog uncoiled los ntawm exonuclease enzyme hu ua DNA helicase. Lub polymerization ntawm deoxyribonucleotides ib txwm pib los ntawm 3' kawg ntawm DNA strand. Muaj ntau ntau hom DNA polymerases, thiab txhua hom muaj cov protein, uas txhais tau hais tias nws muaj cov txheej txheem ntawm cov hauv paus tshwj xeeb rau ib qho enzyme. Muaj txog 900 - 1000 amino acids hauv tib neeg DNA polymerase chains. Feem ntau, thaum lub sij hawm replication txheej txheem, DNA polymerase muaj peev xwm luam cov kab zauv ntawm nitrogenous bases, thiaj li hais tias nws muaj peev xwm tsim ntau zoo tib yam strands los ntawm ib tug enzyme. Qhov kev hloov pauv ntawm cov enzyme no hauv ntau hom tsis tau hais ntau, vim tias cov catalytic subunits ntawm cov qauv enzyme yuav luag tib yam hauv ntau hom. Txawm li cas los xij, raws li cov kev hloov me ntsis ntawm xya tsev neeg ntawm DNA polymerases hu ua A, B, C, D, X, Y, thiab RT tau raug txheeb xyuas. Tag nrho cov hom no muaj sib sau ua ke 15 cov enzymes sib txawv ntawm eukaryotes thiab 5 ntawm prokaryotes.
RNA Polymerase
RNA polymerase yog lub ntsiab enzyme uas catalyses zus tau tej cov RNA strands. Cov qauv ntawm DNA nitrogenous lub hauv paus sequences feem ntau yog tsim los tsim RNA, thiab cov enzyme no muaj peev xwm ua tau ntau yam haujlwm. Ua ntej, qhov tshwj xeeb ntawm DNA strand (feem ntau yog cov noob) yog uncoiled los ntawm kev rhuav cov hydrogen bonds ntawm cov hauv paus sib xws ntawm cov kev tawm tsam los ntawm RNA polymerase. Tom qab ntawd, kev luam ntawm lub hauv paus ib ntus los ntawm kev hloov uracil rau thymine yuav siv sij hawm qhov chaw ntawm 3' kawg mus rau 5' kawg ntawm DNA strand. Lub ntsiab lus pib ntawm RNA polymerization ntawm DNA strand yog hu ua tus txhawb nqa thaum lub sijhawm ua tiav yog lub npe hu ua terminator. Txij li thaum cov enzyme no tsim cov strand siv ribonucleotides, lub sij hawm RNA polymerase yog siv los xa. RNA polymerase tuaj yeem tsim cov khoom lag luam suav nrog tus xa xov RNA, ribosomal RNA, hloov RNA, micro RNA, thiab ribozyme lossis catalytic RNA. Txij li thaum RNA polymerase muaj peev xwm ntawm unwinding DNA strand, nws tsis xav tau lwm yam enzyme los rhuav tshem ob lub helix qauv. Hauv cov kab mob, RNA polymerase yog ob peb yam uas tau sau tseg ua α2, β, β', thiab ω. Cov kab mob RNA polymerases txawv me ntsis rau ib leeg thiab ua haujlwm. Muaj cov cofactors transcriptional uas raug khi rau RNA polymerase ntawm ntau qhov chaw los txhim kho txoj haujlwm, tshwj xeeb tshaj yog nyob rau qee cov kab mob xws li E. coli.
Qhov txawv ntawm DNA Polymerase thiab RNA Polymerase yog dab tsi?
• DNA polymerase tsim cov DNA strand los ntawm deoxyribonucleoties, whereas RNA polymerase tsim RNA strands los ntawm ribonucleoties.
• RNA polymerase muaj peev xwm ua tiav ntau txoj haujlwm ntxiv piv rau qhov DNA polymerase ua tau.
• RNA polymerase tsim ntau yam khoom tab sis tsis yog DNA polymerase.
• DNA polymerase pib ua haujlwm los ntawm 3' kawg ntawm DNA strand, thaum RNA polymerase tuaj yeem pib ua haujlwm ntawm txhua qhov ntawm DNA strand ntawm 3' kawg mus rau 5' kawg kev taw qhia.
