Nucleic acids ua lub luag haujlwm tseem ceeb hauv kev ua kom cov haujlwm tseem ceeb ntawm cov hlwb ntawm cov kab mob muaj sia. Ib tus neeg sawv cev tseem ceeb ntawm pawg no ntawm cov organic tebchaw yog DNA, uas nqa tag nrho cov ntaub ntawv ntawm caj ces thiab yog lub luag haujlwm rau qhov tshwm sim ntawm cov yam ntxwv tsim nyog.
replication yog dab tsi?
Nyob rau hauv cov txheej txheem ntawm kev faib cell, nws yog ib qho tsim nyog yuav tsum tau nce cov nucleic acids nyob rau hauv lub nucleus kom tsis txhob poob cov ntaub ntawv caj ces hauv cov txheej txheem. Nyob rau hauv biology, replication yog duplication ntawm DNA los ntawm synthesis ntawm tshiab strands.
Lub hom phiaj tseem ceeb ntawm cov txheej txheem no yog txhawm rau hloov cov ntaub ntawv caj ces rau cov ntxhais cov hlwb tsis hloov pauv yam tsis muaj kev hloov pauv.
YEnzymes thiab proteins ntawm replication
Dua dua ntawm DNA molecule tuaj yeem muab piv rau cov txheej txheem metabolic hauv cell, uas yuav tsum muaj cov protein tsim nyog. Txij li thaum replication yog ib qho tseem ceeb ntawm cell division hauv biology, yog li ntawd, ntau pab peptides koom nrog ntawm no.
DNA polymerase yog qhov tseem ceeb tshaj plaws reduplication enzyme uas yog lub luag haujlwmrau synthesis ntawm tus ntxhais saw ntawm deoxyribonucleic acid. Nyob rau hauv lub cytoplasm ntawm lub cell, nyob rau hauv tus txheej txheem ntawm replication, lub xub ntiag ntawm nucleic triphosphates yog yuav tsum tau, uas coj tag nrho cov nucleic bases
Cov hauv paus no yog nucleic acid monomers, yog li tag nrho cov saw ntawm cov molecule yog tsim los ntawm lawv. DNA polymerase yog lub luag haujlwm rau cov txheej txheem sib dhos hauv qhov kev txiav txim kom raug, txwv tsis pub txhua yam kev hloov pauv yuav raug zam.
- Primase yog cov protein uas yog lub luag haujlwm rau kev tsim cov primer ntawm DNA template saw. Cov primer no tseem hu ua primer, nws muaj cov qauv ntawm RNA. Rau DNA polymerase enzyme, lub xub ntiag ntawm thawj monomers yog ib qho tseem ceeb, los ntawm uas ntxiv synthesis ntawm tag nrho cov polynucleotide saw yog ua tau. Qhov kev ua haujlwm no yog ua los ntawm cov primer thiab nws cov enzyme sib raug.
- Helicase (helicase) tsim ib rab diav rawg replication, uas yog qhov sib txawv ntawm matrix chains los ntawm kev rhuav tshem hydrogen bonds. Qhov no ua rau nws yooj yim dua rau polymerases mus rau hauv lub molecule thiab pib synthesis.
- Topoisomerase. Yog tias koj xav txog DNA molecule raws li txoj hlua twisted, raws li cov polymerase txav raws cov saw, qhov zoo voltage yuav raug tsim vim muaj zog twisting. Qhov teeb meem no daws tau los ntawm topoisomerase, ib qho enzyme uas tawg cov saw rau ib lub sij hawm luv luv thiab nthuav tawm tag nrho cov molecule. Tom qab ntawd, qhov chaw puas tsuaj yog sewn ua ke dua, thiab DNA tsis ntxhov siab.
- Ssb cov proteins txuas zoo li pawg rau DNA strands ntawm qhov sib txuas ntawm rab rawg kom tiv thaiv kev rov tsim dua ntawm hydrogen bonds ua ntej kawg ntawm kev rov ua dua tshiab.
- Ligas. Enzyme muaj nuj nqimuaj nyob rau hauv stitching Okazaki fragments ntawm lagging strand ntawm DNA molecule. Qhov no tshwm sim los ntawm kev txiav cov primers thiab ntxig ib txwm deoxyribonucleic acid monomers rau hauv lawv qhov chaw.
Nyob rau hauv biology, replication yog ib tug complex txheej txheem ntau yam uas tseem ceeb heev nyob rau hauv lub cell division. Yog li ntawd, kev siv ntau yam proteins thiab enzymes yog qhov tsim nyog rau kev siv tau zoo thiab raug.
Kev rov ua dua tshiab
Muaj 3 txoj kev xav uas piav qhia txog DNA duplication txheej txheem:
- Kev saib xyuas hais tias ib tus ntxhais molecule ntawm nucleic acid muaj qhov xwm txheej matrix, thiab qhov thib ob yog tsim los ntawm kos.
- Semi-conservative npaj los ntawm Watson thiab Crick thiab tau lees paub hauv xyoo 1957 hauv kev sim ntawm E. Coli. Qhov kev xav no hais tias ob tus ntxhais DNA molecules muaj ib qho qub strand thiab ib qho tshiab synthesized.
- Cov txheej txheem dispersion yog raws li kev xav tias cov ntxhais molecules muaj alternating seem raws lawv tag nrho ntev, muaj xws li cov qub thiab tshiab monomers.
Tam sim no scientifically proven semi-conservative qauv. Dab tsi yog replication ntawm qib molecular? Thaum pib, lub helicase rhuav tshem cov hydrogen bonds ntawm DNA molecule, yog li qhib ob lub chains rau polymerase enzyme. Lub tom kawg, tom qab tsim cov noob, pib synthesis ntawm cov saw tshiab nyob rau hauv cov kev taw qhia 5'-3'.
Cov cuab yeej ntawm DNA antiparallelism yog qhov laj thawj tseem ceeb rau kev tsim cov kev coj ua thiab ua lag luam. Nyob rau hauv txoj kab, DNA polymerase txav tsis tu ncua, thaum nyob rau hauv lub laggingnws tsim Okazaki fragments, uas yuav koom ua ke los ntawm ligase yav tom ntej.
Txoj kev rov ua dua
Puas muaj pes tsawg DNA molecules nyob rau hauv lub nucleus tom qab replication? Cov txheej txheem nws tus kheej implies ob npaug ntawm cov noob caj noob ces ntawm tes, yog li ntawd, thaum lub sij hawm hluavtaws ntawm mitosis, lub diploid teeb muaj ob zaug ntau dua DNA molecules. Qhov kev nkag no feem ntau yog 2n 4c.
Ntxiv rau lub ntsiab lus lom neeg ntawm kev rov ua dua tshiab, cov kws tshawb fawb tau pom tias siv cov txheej txheem hauv ntau yam tshuaj thiab kev tshawb fawb. Yog hais tias nyob rau hauv biology replication yog duplication ntawm DNA, ces nyob rau hauv lub chaw soj nstuam, lub reproduction ntawm nucleic acid molecules yog siv los tsim ntau txhiab daim ntawv.
Txoj kev no yog hu ua polymerase chain reaction (PCR). Cov txheej txheem ntawm cov txheej txheem no zoo ib yam li kev rov ua dua hauv vivo, yog li ntawd, cov enzymes zoo sib xws thiab cov tshuab tsis siv neeg siv rau nws cov chav kawm.
Cov Lus Qhia
Kev rov ua dua tshiab yog qhov tseem ceeb heev rau cov kab mob muaj sia. Kev hloov pauv ntawm cov ntaub ntawv caj ces thaum lub sijhawm faib ntawm tes tsis ua tiav yam tsis muaj qhov sib npaug ntawm DNA molecules, yog li kev sib koom ua haujlwm ntawm cov enzymes tseem ceeb ntawm txhua theem.
