Qhov sib txawv tseem ceeb ntawm kev saib xyuas kev saib xyuas kev saib xyuas thiab kev sib cais yog nyob rau hauv hom DNA helices lawv tsim. Conservative replication tsim ob DNA helices nyob rau hauv uas ib tug helix muaj tag nrho cov qub DNA, thiab lwm yam helix muaj tag nrho DNA tshiab thaum semiconservative replication tsim ob helices nyob rau hauv uas txhua helix muaj ib tug tshiab strand thiab ib tug qub strand; dispersive replication, ntawm qhov tod tes, tsim ob lub helices uas txhua strand muaj alternating ntu ntawm qub thiab tshiab DNA.
DNA feem ntau tshwm sim ua ob lub helix uas muaj ob txoj hlua sib txuas. DNA replication yog tus txheej txheem ntawm tsim cov replicas los yog zoo tib yam luam ntawm DNA los ntawm thawj DNA molecules. Nws yog ib txoj kev tseem ceeb heev uas pab txhawb kev hla ntawm cov khoom siv caj ces los ntawm niam txiv mus rau cov xeeb ntxwv. Hauv lwm lo lus, DNA replication yog lub hauv paus ntawm heredity lossis biological qub txeeg qub teg. Muaj peb txoj hauv kev ntawm DNA replication li semiconservative replication, conservative replication, thiab dispersive replication.
Kev Tiv Thaiv Kev Txhaum Cai yog dab tsi?
Kev saib xyuas kev rov ua dua yog ib qho ntawm peb tus qauv ntawm DNA replication. Cov txheej txheem no tsim ob DNA helices los ntawm ib tug thawj DNA helix. Tawm ntawm ob lub helices tsim, ib lub helix muaj tag nrho cov laus lossis niam txiv DNA thaum lwm lub helix muaj DNA tshiab nkaus.
Daim duab 01: Peb Cov Qauv Rov Ua Dua
Tsis tas li ntawd, hom kev rov ua dua no tsis pom tias muaj txiaj ntsig zoo. Cov kws tshawb fawb ntseeg tias niam txiv DNA tsis sib cais qhib rau hauv cov qauv no txhua. Lawv kuj tau sib cav hais tias tag nrho cov tshiab thiab cais daim qauv ntawm DNA cov qauv hauv cov qauv no, qee yam ua rau niam txiv cov hlua tsis zoo.
Semiconservative Replication yog dab tsi?
Semiconservative replication yog tus qauv tseem ceeb ntawm DNA replication uas tau thov los ntawm Watson thiab Crick hauv xyoo 1953. Nyob rau hauv txoj kev no, tawm ntawm ob lub helices tsim, txhua lub helix muaj ib txoj hlua tshiab thiab ib qho qub los yog niam txiv strand. Raws li Watson thiab Crick, thaum lub sij hawm replication semiconservative, ib tug qub DNA strand ua hauj lwm raws li ib tug template los tsim cov strand tshiab. Li no, txhua qhov tshiab ob lub helix tsim muaj ib qho qub DNA strand txhua zaus.
Daim duab 02: Semi Conservative Replication
Yog li ntawd, tus qauv ntawm DNA replication no suav hais tias yog qhov muaj txiaj ntsig ntau dua li ob tus qauv. Nws yog vim DNA polymerase enzyme xav tau ib tug qauv strand los tsim ib tug tshiab strand thiab muaj peev xwm ntawm combining ib tug tshiab strand nrog lub template strand thaum replication.
Dab tsi yog kev hloov pauv?
Dispersive replication yog tus qauv thib peb ntawm DNA replication. Tus qauv tsim cov DNA helices uas muaj qhov sib xyaw ntawm DNA qub thiab tshiab. Yog li, txhua txoj hlua tshiab hauv lub helix yog patchwork ntawm DNA qub thiab tshiab. Hauv cov lus yooj yooj yim, tag nrho cov strands hauv DNA helices muaj alternating niam txiv thiab DNA tshiab, raws li tau piav qhia hauv cov qauv no. Cov kws tshawb fawb ntseeg tias DNA tsuas yog luam tawm nws tus kheej rau cov chunks luv luv ntawm ib lub sijhawm los tsim cov qauv hloov pauv ntawm DNA.
Dab tsi yog qhov zoo sib xws ntawm Conservative Semiconservative thiab Dispersive Replication?
- Kev saib xyuas, kev saib xyuas ib puag ncig thiab kev sib cais yog peb tus qauv ntawm DNA replication.
- Txhua tus qauv tsim DNA helices uas muaj ob txoj hlua sib txuas.
Dab tsi yog qhov txawv ntawm Conservative Semiconservative thiab Dispersive Replication?
Kev khaws cia rov ua dua tsim ob lub helices, ib qho muaj DNA qub tag nrho thaum lwm qhov muaj DNA tshiab nkaus. Semiconservative replication yog qhov kev xav ntawm DNA replication uas ua rau ob lub helices, txhua tus muaj ib qho qub strand thiab ib txoj hlua tshiab. Dispersive replication, ntawm qhov tod tes, tsim ob lub helices nyob rau hauv uas txhua strand muaj alternating ntu ntawm qub thiab tshiab DNA. Yog li, qhov no yog qhov sib txawv tseem ceeb ntawm kev saib xyuas kev noj qab haus huv semiconservative thiab dispersive replication.
Summary – Conservative Semiconservative vs Dispersive Replication
Muaj peb tus qauv uas piav qhia txog DNA replication hauv cov kab mob nyob. Lawv yog conservative replication, semiconservative replication, thiab dispersive replication. Conservative replication tsim ib lub helix uas muaj tag nrho DNA qub thiab lwm yam helix uas muaj DNA tshiab nkaus. Nyob rau hauv sib piv, tus qauv semiconservative tsim ob helices, thiab txhua tus muaj ib txoj hlua ntawm DNA qub thiab ib txoj hlua ntawm DNA tshiab. Meanwhile, tus qauv dispersive tsim DNA helices nyob rau hauv uas txhua strand muaj alternating segments ntawm tshiab thiab qub DNA. Yog li, qhov no yog qhov sib txawv tseem ceeb ntawm kev saib xyuas kev noj qab haus huv semiconservative thiab dispersive replication.
Image Courtesy:
1. "Semi-Conservative DNA Replication: Meselson thiab Stahl." Nature News, Nature Publishing Group, Available here.
2. "Hom ntawm DNA Replication: Meselson-Stahl Experiment." Khan Academy, Muaj nyob ntawm no.
Image Courtesy:
1. “DNAreplicationModes” Los ntawm Tus Thawj uploader yog Adenosine ntawm English Wikipedia. - Hloov ntawm en.wikipedia rau Commons (CC BY-SA 2.5) ntawm Commons Wikimedia
2. "Semiconservative replication" Los ntawm Lizanne Koch - lgkoch - tus kheej ua haujlwm nrog chemdraw (Public Domain) ntawm Commons Wikimedia
