Qhov sib txawv tseem ceeb ntawm kev txwv endonuclease thiab exonuclease yog qhov txwv endonuclease yog ib qho enzyme nuclease uas paub txog DNA ib ntus thiab tshem tawm cov DNA nyob rau hauv lossis nyob ib sab ntawm cov kab ke, thaum exonuclease yog ib qho nuclease enzyme uas cleaves cov nucleotides hauv ib qho. polynucleotide los ntawm 5' kawg lossis 3' kawg ib zaug.
Nucleases yog cov enzymes uas tshem cov phosphodiester bonds ntawm nucleotides ntawm nucleic acids. Hauv cov kab mob muaj sia, lawv yog cov cuab yeej tseem ceeb rau ntau yam ntawm DNA kho hauv lub cell. Qhov tsis xws ntawm cov enzymes no tuaj yeem ua rau muaj kev tsis sib haum xeeb thiab kev tiv thaiv kab mob. Cov kev txwv nucleases yog cov nucleases tshwj xeeb uas nws txoj haujlwm yog nyob ntawm qhov tshwj xeeb nucleotide ib ntus. Ib qho piv txwv yog txwv endonuclease. Muaj ib qho kev faib tawm rau nucleases raws li qhov chaw ntawm kev ua haujlwm, xws li endonuclease thiab exonuclease. Endonuclease digests cheeb tsam nyob rau hauv nruab nrab ntawm lub hom phiaj DNA molecule. Exonuclease digests nucleic acids los ntawm qhov kawg. Li no, txwv endonuclease thiab exonuclease yog ob hom nuclease enzymes.
Kev txwv Endonuclease yog dab tsi?
Txoj kev txwv endonuclease yog ib qho enzyme nuclease uas paub txog DNA ib ntus thiab tshem tawm cov DNA hauv lossis nyob ib sab ntawm cov kab ke ntawd. Qhov tshwj xeeb DNA ib ntus hu ua qhov chaw txwv. Nws tseem hu ua txwv enzyme lossis restrictase. Kev txwv endonuclease yog ib qho enzyme tshwj xeeb. Nws yog ib chav kawm ntawm cov pab pawg endonuclease dav ntawm cov enzymes. Kev txwv endonucleases feem ntau muab faib ua tsib hom, uas txawv ntawm lawv cov qauv thiab muaj peev xwm txiav cov DNA substrate ntawm qhov chaw lees paub.5 hom yog hom I, hom II, hom III, hom IV thiab hom V.
Daim duab 01: Kev txwv Endonuclease
Kev txwv endonucleases feem ntau pom muaj nyob hauv cov kab mob thiab archaea. Lawv muab cov txheej txheem tiv thaiv kab mob tiv thaiv kab mob. Muaj ntau tshaj 3600 paub txwv endonucleases. Lawv sawv cev ntau dua 250 qhov tshwj xeeb sib txawv. Ntau tshaj 3000 ntawm cov no tau kawm kom ntxaws. Tsis tas li ntawd, ntau dua 800 ntawm cov no muaj nyob rau hauv kev lag luam.
Exonuclease yog dab tsi?
Exonuclease yog ib qho enzyme nuclease uas tshem cov nucleotides hauv ib lub polynucleotide los ntawm 5' kawg lossis 3' kawg ib zaug. Qhov no tshwm sim los ntawm hydrolysing cov tshuaj tiv thaiv uas rhuav tshem phosphodiester bonds ntawm nucleotides thaum kawg. Eukaryotes thiab prokaryotes muaj peb hom exonucleases. Cov exonucleases no koom nrog hauv ib txwm hloov pauv ntawm mRNA. Lawv yog 5' rau 3' exonuclease (Xrn1), 3' txog 5' exonuclease, thiab poly-A tshwj xeeb 3' txog 5' exonuclease. 5 'mus rau 3' exonuclease yog ib qho khoom noj muaj protein ntau. 3' mus rau 5' exonuclease yog cov protein ywj siab. Poly A tshwj xeeb 3' txog 5' exonuclease tseem hu ua poly-A tshwj xeeb ribonuclease koom nrog hauv exonucleolytic degradation ntawm poly-A tail.
Daim duab 02: Exonuclease
Nyob rau hauv ob qho tib si archaea thiab eukaryotes, RNA degradation yog ua los ntawm ntau cov protein exosome complex uas muaj 3' txog 5' exoribonucleases.
Dab tsi yog qhov zoo sib xws ntawm Kev Txwv Endonuclease thiab Exonuclease?
- Kev txwv endonuclease thiab exonuclease yog ob hom nuclease enzymes.
- Ob lub enzymes txiav DNA molecules.
- Cov enzymes no muaj nyob hauv prokaryotes.
- YLawv yog cov protein.
Qhov txawv ntawm Kev Txwv Endonuclease thiab Exonuclease yog dab tsi?
Kev txwv endonuclease yog ib qho nuclease enzyme uas paub txog DNA ib ntus thiab tshem tawm cov DNA nyob rau hauv lossis nyob ib sab ntawm qhov sib lawv liag, thaum exonuclease yog ib tug nuclease enzyme uas cleaves cov nucleotides nyob rau hauv ib polynucleotide los ntawm tog twg los 5' kawg lossis 3' kawg. ib zaug ib zaug. Yog li, qhov no yog qhov sib txawv tseem ceeb ntawm kev txwv endonuclease thiab exonuclease. Ntxiv mus, txwv endonuclease tsuas yog pom nyob rau hauv prokaryotes, thaum exonuclease pom nyob rau hauv ob qho tib si prokaryotes thiab eukaryotes.
Cov infographic hauv qab no teev qhov sib txawv ntawm kev txwv endonuclease thiab exonuclease hauv daim ntawv teev npe rau ib sab ntawm kev sib piv.
Summary – Kev txwv Endonuclease vs Exonuclease
Nucleases yog cov enzymes uas rhuav tshem phosphodiester bonds ntawm nucleotides ntawm nucleic acids. Kev txwv endonuclease thiab exonuclease yog ob hom nuclease enzymes. Kev txwv endonuclease yog ib qho enzyme nuclease uas paub txog DNA ib ntus thiab cleaves DNA nyob rau hauv los yog nyob ib sab ntawm qhov sib lawv liag. Exonuclease yog ib qho enzyme nuclease uas tshem tawm cov nucleotides hauv polynucleotide los ntawm lawv 5' kawg lossis 3' kawg ib zaug. Yog li, qhov no qhia txog qhov sib txawv ntawm kev txwv endonuclease thiab exonuclease.
