Qhov Tseem Ceeb Qhov txawv - Endonuclease vs Exonuclease
Ua ntej saib qhov sib txawv ntawm endonuclease thiab exonuclease, nws yog ib qho tseem ceeb kom paub tseeb tias lub nuclease yog dab tsi. Lub nuclease yog ib qho enzyme uas muaj peev xwm tshem tawm phosphodiester bonds ntawm nucleotides hauv nucleic acids. Endonuclease thiab exonuclease yog ob qhov kev faib tawm ntawm nucleases. Qhov sib txawv tseem ceeb ntawm endonuclease thiab exonuclease yog endonucleases cleave cov bonds ntawm nucleotides nyob rau hauv cov nucleic acid molecule whereas exonucleases cleave cov nyiaj ntawm nucleotides ntawm 3 'los yog 5' kawg ntawm nucleic acid molecule.
Nuclease yog dab tsi?
A nuclease yog ib qho enzyme uas muaj peev xwm tshem tawm phosphodiester bonds ntawm nucleotides hauv nucleic acids. Nws belongs rau hydrolase enzyme pawg vim nws hydrolyzes tshuaj bonds ntawm nucleotides. Cov enzyme no yog qhov tseem ceeb rau cov txheej txheem kho DNA zoo uas tshwm sim hauv cov hlwb thiab hauv cov txheej txheem biotechnological xws li gene cloning, recombinant DNA technology, RFLP, AFLP, gene sequencing, gene therapy, genome mapping etc.
Muaj ob hom nucleases loj: ribonuclease thiab deoxyribonuclease, uas ua thiab rhuav tshem cov tshuaj sib txuas ntawm monomers ntawm RNA thiab DNA, raws li. Raws li qhov chaw ntawm kev ua ntawm nucleases, lawv tau muab faib ua ob pawg xws li endonuclease thiab exonuclease. Endonucleases paub txog qee thaj tsam ntawm nucleic acids thiab tshem tawm cov phosphodiester bonds ntawm nucleotides uas nyob rau hauv nruab nrab ntawm cov nucleic acids. Exonucleases cleave phosphodiester bonds ntawm nucleotides uas nyob rau ntawm qhov kawg ntawm cov nucleic acids.
Daim duab 1: Nuclease Activity
Dab tsi yog Endonuclease?
Endonuclease yog ib hom nucleases uas cleaves nucleic acids los ntawm nruab nrab. Nws paub txog cov nucleotide ib ntus ntawm nucleic acid thiab rhuav tshem cov tshuaj sib txuas ntawm nucleotides. Lawv kuj tseem hu ua kev txwv endonucleases vim lawv tshawb nrhiav qhov chaw txwv thiab tshem tawm cov ntawv cog lus thiab tsim cov khoom txwv. Ntau tshaj 100 qhov kev txwv endonucleases tau txheeb xyuas cov kab mob thiab archaea thiab tau txais los ua lag luam.
Kev txwv endonucleases tau siv dav hauv biotechnology. Lawv ua lub luag haujlwm tseem ceeb hauv molecular cloning. Feem ntau ntawm lawv yog dimeric enzymes uas muaj ob lub protein subunits. Ob tug protein subunits qhwv ob-stranded DNA thiab cais cleave ob strands los ntawm ob sab. Muaj ntau pua hom kev txwv endonucleases nrog cov chaw paub tshwj xeeb hauv cov kab mob. Vim lawv qhov tshwj xeeb tshwj xeeb hauv kev txwv, lawv cleave tsuas yog ntawm cov kab ke tshwj xeeb. Yog li ntawd, lawv raug suav hais tias yog cov cuab yeej molecular muaj txiaj ntsig zoo hauv kev siv DNA thev naus laus zis. Yog tsis muaj kev txwv endonucleases, kev tsim cov DNA molecule recombinant tsis tuaj yeem ua tau. Kev tsim cov DNA molecule recombinant yog cov kauj ruam yooj yim ntawm feem ntau molecular biological technologies.
Yuav kom nkag siab txog qhov sib txawv ntawm kev lees paub los ntawm kev txwv endonucleases, cov piv txwv hauv qab no yuav pab cov neeg nyeem.
Bam HI yog txwv tsis pub endonuclease uas tshawb nrhiav qhov chaw txwv hauv qab no hauv DNA molecule (qhov chaw qhia hauv cov ntawv liab).
Thaum Bam HI cleaves cov nucleic acid los ntawm qhov chaw txwv, nws tsim ob ntu nram qab no.
EcoRI yog lwm qhov kev txwv endonuclease uas muaj txiaj ntsig zoo hauv kev sib txuas DNA thev naus laus zis ua rau nws qhov tshwj xeeb txwv qhov chaw lees paub thiab cleaves DNA raws li qhia hauv daim duab 2.
Daim duab 2: EcoRI
Exonuclease yog dab tsi?
Exonuclease yog ib qho enzyme nuclease uas cleaves tshuaj bonds ntawm nucleotides ntawm 3 'los yog 5' kawg ntawm nucleic acid chains. Nws rhuav tshem ib qho nucleotides kawg ntawm cov saw hlau thiab tsim cov nucleosides los ntawm kev xa cov phosphate pawg mus rau dej. Exonucleases muaj nyob rau hauv archaea, kab mob, thiab eukaryotes. Hauv E coli, muaj 17 txawv exonucleases tam sim no suav nrog DNA polymeras 1, 2 thiab 3. Ntau DNA polymerases nthuav tawm 3' txog 5' exonuclease proofreading ua haujlwm.
Exonucleases tseem ceeb hauv kev kho DNA, genetic recombination, tiv thaiv qhov tshwm sim ntawm kev hloov pauv, genome stabilization thiab lwm yam.
Daim duab 3: Exonuclease kev ua ntawm RecBCD ntawm E Coli
Qhov txawv ntawm Endonuclease thiab Exonuclease yog dab tsi?
YEndonuclease vs Exonuclease |
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| Endonuclease yog ib hom nuclease enzymes uas cleaves bonds ntawm nucleotides nyob rau hauv lub nucleic acid molecule. | Exonuclease yog ib hom nuclease enzymes uas tshem tawm qhov sib txuas ntawm nucleotides ntawm 3' lossis 5' kawg ntawm nucleic acid molecule. |
| khoom kawg | |
| Endonucleases tsim oligonucleotide txwv tsis pub tawg | Exonucleotides tsim nucleosides |
| Lawv tawg phosphodiester daim ntawv cog lus thiab tsim cov khoom txwv. Tab sis lawv tsis tshem cov nucleotides ib zaug. | Lawv tshem tawm nucleotides ib los ntawm ib qho los ntawm qhov kawg ntawm nucleic acids. |
| Examples | |
| Piv txwv suav nrog Bam HI, EcoRI, Hind III, Hpa I, Sma I, | Piv txwv suav nrog Exonuclease I, Exonuclease III, RecBCD (Exonuclease V), RecJ exonuclease, Exonuclease VIII / RecE, Exonuclease IX, Exonuclease T, Exonuclease X thiab lwm yam. |
Summary – Endonuclease vs Exonuclease
Nucleases yog lub luag haujlwm rau kev rhuav tshem cov tshuaj phosphodiester ntawm nucleotides ntawm nucleic acids. Nucleases tuaj yeem ua rau hauv lossis ntawm qhov kawg ntawm cov saw nucleic acid. Raws li qhov chaw ntawm qhov kev txiav txim, ob lub ntsiab ntawm nucleases muaj nyob rau hauv cov kab mob. Lawv yog endonuclease thiab exonuclease. Endonucleases cleave nucleotides los ntawm nruab nrab ntawm cov saw thaum exonucleases cleave nucleotides los ntawm qhov kawg ntawm cov nucleic acid saw. Endonucleases yog ib qho tseem ceeb heev nyob rau hauv recombinant DNA thev naus laus zis txij li thaum lawv paub txog cov txheej txheem hauv paus hauv nucleic acid saw thiab rhuav tshem cov ntawv cog lus ntawm nucleotides.
