Qhov sib txawv tseem ceeb ntawm dNTP thiab ddNTP yog tias dNTP lossis deoxyribonucleotides yog lub tsev thaiv DNA thiab muaj 3ʹ-OH pawg ntawm pentose qab zib qauv thaum ddNTP lossis dideoxynucleoside triphosphates yog nucleotides uas tsis muaj 3ʹ-OH pawg thiab lawv. yog siv hauv Sanger dideoxy DNA sequencing txheej txheem los tsim cov DNA ntev sib txawv.
dNTP thiab ddNTP yog nucleotides. dNTP hais txog deoxyribose nucleotides. Lawv yog lub tsev blocks ntawm DNA. dNTPs yog siv los tsim cov DNA. dNTP, ntawm qhov tod tes, hais txog Dideoxynucleoside triphosphates. Lawv tau siv hauv Sanger sequencing los txiav tawm DNA synthesis ntawm qhov ntev sib txawv. Lawv tsis muaj OH pawg ntawm 3ʹ txoj haujlwm. Ib qho hydrogen tam sim no nyob rau ntawm txoj hauj lwm 3ʹ es tsis yog OH pawg. Yog li ntawd, ddNTPs tsis tuaj yeem tsim ib daim ntawv cog lus phosphodiester nrog cov nucleotide tom ntej. dNTP muaj peev xwm ua tiav cov synthesis ntawm DNA, thaum ddNTP muaj peev xwm txiav tawm cov polymerization ntawm DNA.
dNTP yog dab tsi?
dNTP sawv cev rau deoxyribose nucleotide lossis deoxyribonucleotide. Nws yog lub tsev thaiv DNA. Muaj plaub hom dNTPs. Lawv yog dATP, dTTP, dCTP thiab dGTP. Lawv muaj npe raws li purine lossis pyrimidine nitrogenous hauv paus: Adenine (A), Guanine (G), Thymine (T) thiab Cytosine (C).
Figure 01: dNTP
Adenine thiab guanine yog purine hauv paus thaum thymine thiab cytosine yog pyrimidine hauv paus. Pentose qab zib ntawm dNTP yog deoxyribose. Kuj tseem muaj ib pab pawg phosphate. Yog li ntawd, dNTP yog tsim los ntawm peb yam: ib tug nitrogenous puag, deoxyribose qab zib thiab ib pawg phosphate. Cov dNTPs no ua ke nrog ib leeg ntawm phosphodiester bonds. Hauv dNTPs, muaj ib pab pawg OH txuas rau txoj hauj lwm 3ʹ ntawm pentose qab zib uas yuav tsum tau tsim kom muaj kev sib txuas nrog phosphate pawg txuas nrog 5ʹ carbon ntawm qab zib ntawm nucleotide tom ntej. Txij li thaum tag nrho cov dNTPs muaj 3ʹ -OH pawg, lawv muaj peev xwm ua ke thiab txuas ntxiv DNA strands. Yog li, dNTP ua raws li qhov tseem ceeb rov ua dua chav tsev ntawm DNA thiab tshuaj lom neeg ntawm cov noob. Lub synthesis ntawm DNA ib txwm ua los ntawm 5ʹ mus rau 3ʹ.
DdNTP yog dab tsi?
Sanger sequencing yog thawj tiam DNA sequencing txoj kev tsim los ntawm Frederick Sanger thiab nws cov tsev kawm ntawv qib siab hauv xyoo 1977. Nws tseem hu ua Chain Termination Sequencing lossis Dideoxy sequencing vim lub hauv paus ntsiab lus ntawm txoj kev no yog cov saw txiav siv Dideoxynucleoside triphosphates. (ddNTPs). ddNTPs yog nucleotides siv hauv Sanger sequencing. Sanger sequencing yog raws li kev xaiv koom ua ke ntawm ddNTPs thiab kev txiav tawm ntawm DNA synthesis thaum lub sij hawm in vitro DNA replication. Qhov tshwj xeeb ntawm ddNTPs yog tias lawv tsis muaj 3ʹ-OH pawg ntawm pentose qab zib kom txuas ntxiv phosphodiester daim ntawv cog lus ntawm pawg phosphate ntawm 5ʹ hauv cov nucleotide uas nyob ib sab. Li no, ib zaug ib lub ddNTP txuas nrog rau cov hlua txuas ntxiv, cov saw elongation nres thiab xaus ntawm qhov ntawd. ddNTPs ua raws li cov saw-elongating inhibitors ntawm DNA polymerase thaum lub sij hawm Sanger sequencing method.
Figure 02: ddNTP
Muaj plaub ddNTPs: ddATP, ddCTP, ddGTP thiab ddTTP siv hauv Sanger sequencing. Cov nucleotides nres cov txheej txheem DNA rov ua dua thaum lawv tau muab tso rau hauv cov kab loj hlob ntawm DNA. Raws li qhov tshwm sim, Sanger sequencing tsim qhov ntev ntawm DNA luv. Capillary gel electrophoresis yog siv los npaj cov DNA luv luv los ntawm lawv qhov ntau thiab tsawg ntawm cov gel. ddNTPs yog cov xov tooj cua lossis fluorescently sau nrog cov xim sib txawv rau qhov yooj yim ntawm kev txheeb xyuas DNA ib ntus. Los ntawm kev tshuaj xyuas cov gel, cov nucleotide ib ntus ntawm DNA tsis paub tseeb tuaj yeem txiav txim siab.
Dab tsi yog qhov zoo sib xws ntawm dNTP thiab DdNTP?
- Ob leeg dNTP thiab ddNTP yog siv hauv Sanger sequencing.
- Muaj plaub hom dNTPs thiab ddNTPs.
- Lawv muaj peb yam: nitrogenous puag, deoxyribose qab zib thiab phosphate pawg.
Qhov txawv ntawm dNTP thiab DdNTP yog dab tsi?
dNTP yog ib qho ntawm plaub hom deoxyribonucleotides uas tsim cov blocks ntawm DNA. ddNTP yog ib qho ntawm plaub hom Dideoxyribonucleoside triphosphates siv hauv Sanger sequencing txheej txheem. dNTP muaj 3ʹ-OH pawg ntawm cov suab thaj pentose thaum ddNTP tsis muaj 3ʹ-OH pawg ntawm cov suab thaj pentose. Yog li, qhov no yog qhov sib txawv tseem ceeb ntawm dNTP thiab ddNTP. Ntxiv mus, dNTPs nqa tawm DNA polymerization thaum ddNTPs txiav DNA polymerization. Li no, qhov no yog lwm qhov sib txawv loj ntawm dNTP thiab ddNTP.
Cov duab hauv qab no qhia qhov sib txawv ntawm dNTP thiab ddNTP hauv daim ntawv teev npe.
Summary – dNTP vs DdNTP
Ib txwm dNTPs yog tsim cov blocks ntawm DNA thaum ddNTPs yog nucleotides siv hauv Sanger sequencing txheej txheem. dNTP muaj 3ʹ-OH thaum ddNTP tsis muaj 3ʹ-OH. Yog li, qhov no yog qhov sib txawv tseem ceeb ntawm dNTP thiab ddNTP. Ntxiv mus, dNTP tuaj yeem tsim cov DNA strand thaum ddNTP tuaj yeem txiav tawm DNA polymerization. Yog li ntawd, ddNTPs yog siv nyob rau hauv Sanger sequencing thiaj li yuav tsim cov DNA sib txawv nrog ntev sib txawv. Thaum lub sij hawm Sanger sequencing, dNTP thiab ddNTP suav nrog.
