Biologists hu lub sij hawm "transcription" ib theem tshwj xeeb ntawm kev siv cov ntaub ntawv keeb kwm yav dhau los, cov ntsiab lus ntawm qhov uas los ntawm kev nyeem cov noob thiab tsim kom muaj RNA molecule ntxiv rau nws. Nws yog cov txheej txheem enzymatic uas cuam tshuam nrog kev ua haujlwm ntawm ntau cov enzymes thiab cov tshuaj lom neeg lom neeg. Nyob rau tib lub sijhawm, feem ntau ntawm biocatalysts thiab cov txheej txheem ua lub luag haujlwm rau kev tsim cov noob replication tsis paub txog kev tshawb fawb. Vim li no, nws tseem yuav pom nyob rau hauv nthuav dav dab tsi transcription yog (hauv biology) ntawm qib molecular.
Realization of genetic information
Kev tshawb fawb niaj hnub hais txog kev hloov pauv, nrog rau kev xa xov ntawm cov ntaub ntawv keeb kwm, tsis paub zoo. Feem ntau ntawm cov ntaub ntawv tuaj yeem sawv cev raws li ib theem ntawm cov kauj ruam hauv cov protein biosynthesis, uas ua rau nws nkag siab txog cov txheej txheem ntawm cov noob qhia. Protein synthesis yog ib qho piv txwv ntawm kev paub txog keeb kwm ntawm cov ntaub ntawv keeb kwm, txij li cov noob encodes nws cov qauv tseem ceeb. Rau txhua tus protein molecule, yog nws cov qauv protein, ib qho enzyme, lossisTus neeg nruab nrab, muaj thawj cov amino acid ib ntus sau tseg hauv cov noob.
Thaum nws tsim nyog los rov ua kom cov protein ntau, cov txheej txheem ntawm "unpacking" DNA thiab nyeem cov lej ntawm cov noob xav tau pib, tom qab ntawd cov ntawv sau tau tshwm sim. Nyob rau hauv biology, cov txheej txheem ntawm xws li ib tug txheej txheem muaj peb theem, conventionally txheeb xyuas: pib, elongation, txiav. Txawm li cas los xij, tseem tsis tau muaj peev xwm tsim cov xwm txheej tshwj xeeb rau lawv qhov kev soj ntsuam thaum lub sijhawm sim. Cov no yog cov theoretical laij lej uas tso cai rau kev nkag siab zoo ntawm kev koom tes ntawm enzyme systems hauv cov txheej txheem ntawm kev luam cov noob mus rau RNA template. Ntawm nws qhov tseem ceeb, kev sau ntawv yog cov txheej txheem ntawm RNA synthesis raws li despiralized 3'-5'-strand ntawm DNA.
Kev hloov pauv txoj cai
Koj tuaj yeem nkag siab qhov kev hloov pauv yog dab tsi (hauv biology) siv piv txwv ntawm tus xa xov RNA synthesis. Nws pib nrog "tso tawm" ntawm cov noob thiab kev ua kom zoo ntawm cov qauv ntawm DNA molecule. Nyob rau hauv lub nucleus, cov ntaub ntawv keeb kwm yog nyob rau hauv condensed chromatin, thiab cov noob tsis muaj zog yog compactly "packed" rau hauv heterochromatin. Nws despiralization tso cai rau cov noob xav tau tso tawm thiab ua kom muaj kev nyeem ntawv. Tom qab ntawd ib qho enzyme tshwj xeeb faib cov DNA ob npaug rau hauv ob txoj hlua, tom qab ntawd nyeem 3'-5'-strand code.
Los ntawm lub sijhawm no, lub sijhawm sau ntawv nws tus kheej pib. Lub enzyme DNA-dependent RNA polymerase sib sau ua ke pib ntu ntawm RNA, uas thawj nucleotide txuas nrog, ntxiv rau3'-5'-strand ntawm DNA template cheeb tsam. Tsis tas li ntawd, cov saw hlau RNA tsim, uas kav ntev li ob peb teev.
Qhov tseem ceeb ntawm kev sau ntawv hauv biology yog muab tsis yog rau kev pib ntawm RNA synthesis, tab sis kuj rau nws qhov kev txiav tawm. Mus txog qhov kawg ntawm thaj tsam ntawm cov noob pib qhov kev txiav txim siab ntawm kev nyeem ntawv thiab ua rau kev tso tawm ntawm cov txheej txheem enzymatic txhawm rau tshem tawm DNA-dependent RNA polymerase los ntawm DNA molecule. Tshooj faib ntawm DNA yog kiag li "crosslinked". Tsis tas li ntawd, thaum lub sijhawm sau ntawv, cov tshuab enzyme ua haujlwm "xyuas" qhov tseeb ntawm qhov sib ntxiv ntawm nucleotides thiab, yog tias kev sib xyaw ua haujlwm tsis raug, "txiav" ntu tsis tsim nyog. Kev nkag siab txog cov txheej txheem no tso cai rau peb los teb cov lus nug ntawm dab tsi yog transcription hauv biology thiab nws raug tswj li cas.
Reverse transcription
Kev txhais lus yog cov txheej txheem thoob ntiaj teb rau kev hloov cov ntaub ntawv caj ces ntawm ib tus neeg nqa khoom mus rau lwm tus, piv txwv li los ntawm DNA rau RNA, raws li nws tshwm sim hauv cov hlwb eukaryotic. Txawm li cas los xij, hauv qee cov kab mob, cov kab ke ntawm cov noob hloov pauv tuaj yeem thim rov qab, uas yog, cov cai tau nyeem los ntawm RNA mus rau ib leeg-stranded DNA. Cov txheej txheem no hu ua thim rov qab, thiab nws yog qhov tsim nyog los xav txog qhov piv txwv ntawm tib neeg kis tus kab mob HIV.
Cov txheej txheem thim rov qab zoo li kev qhia tus kab mob mus rau hauv lub xovtooj ntawm tes thiab kev sib txuas ntawm DNA raws li nws RNA siv cov enzyme thim rov qab transcriptase (revertase). Qhov biocatalyst no pib tshwm sim nyob rau hauv lub cev kab mob thiab yog qhib thaum nws nkag mus rau tib neeg lub cell. Nws tso caisynthesize DNA molecule nrog cov ntaub ntawv caj ces los ntawm nucleotides pom hauv tib neeg lub hlwb. Qhov tshwm sim ntawm kev ua tiav ntawm kev rov qab ua tiav yog kev tsim cov DNA molecule, uas, los ntawm kev sib xyaw enzyme, tau nkag mus rau hauv DNA ntawm lub xov tooj ntawm tes thiab hloov kho nws.
Qhov tseem ceeb ntawm kev hloov pauv hauv genetic engineering
Ib qho tseem ceeb, qhov kev hloov pauv hloov pauv hauv biology no ua rau peb cov lus xaus. Ua ntej, cov kab mob no nyob rau hauv cov ntsiab lus phylogenetic yuav tsum muaj ntau dua li ib leeg-celled life forms. Qhov thib ob, qhov no yog pov thawj ntawm qhov muaj peev xwm ntawm lub neej ntawm ib leeg-stranded DNA molecule. Yav dhau los, muaj kev xav tias DNA tuaj yeem nyob tau ntev tsuas yog nyob rau hauv daim ntawv ntawm ob txoj hlua khi.
Thib peb, txij li tus kab mob tsis tas yuav tsum muaj cov ntaub ntawv hais txog nws cov noob los koom ua ke rau hauv DNA ntawm cov hlwb ntawm cov kab mob, nws tuaj yeem ua pov thawj tias cov noob caj noob ces tuaj yeem nkag mus rau hauv cov caj ces ntawm txhua yam kab mob los ntawm kev thim rov qab. kev sau ntawv. Cov lus xaus kawg tso cai rau kev siv cov kab mob ua cov cuab yeej siv tshuaj genetic engineering rau embedding qee cov noob rau hauv genome ntawm cov kab mob.
