Qhov txawv ntawm DNA thiab cDNA yog qhov DNA muaj ob qho tib si exons thiab introns thaum cDNA tsuas muaj exons.
DNA thiab cDNA yog ob hom nucleic acids uas yog tsim los ntawm deoxyribonucleotides. DNA yog ib qho tseem ceeb tshaj plaws macromolecules ntawm cov kab mob nyob uas ua rau lub genome. Lub genome muaj tag nrho cov ntaub ntawv ntawm caj ces ntawm lub cev. Nws suav nrog ntau hom kab ke suav nrog exons uas yog coding sequences thiab introns uas tsis yog coding sequences. Ntawm qhov tod tes, cDNA lossis ntxiv DNA yog lwm hom DNA uas yog tsim los ntawm mRNA molecules los ntawm cov kws tshawb fawb. Txij li thaum cDNA muab los ntawm mRNA cov qauv, nws tsis muaj cov txheej txheem tsis-coding lossis introns.
YDNA yog dab tsi?
Deoxyribonucleic acid lossis DNA ua cov khoom siv caj ces ntawm ntau cov kab mob nyob nrog rau cov kab mob. Cov ntaub ntawv caj ces nyob hauv DNA molecules nyob rau hauv daim ntawv ntawm nucleotide sequences thiab noob. Thaum yug me nyuam, niam txiv DNA kis mus rau cov xeeb ntxwv ntawm gametes. Raws li txoj cai, DNA yog macromolecule tsim los ntawm monomers ntawm deoxyribonucleotides. Deoxyribonucleotide muaj peb yam; deoxyribose qab zib, ib tug nitrogenous puag (adenine, guanine, cytosine thiab thymine) thiab ib pawg phosphate. Tsis tas li ntawd, DNA molecules muaj nyob ua ob lub helix ua los ntawm ob qho ntxiv DNA strands txuas los ntawm hydrogen bonds ntawm complementary nitrogenous bases. Raws li, muaj ob lub hydrogen bonds ntawm adenine thiab thymine thaum muaj peb hydrogen bonds ntawm cytosine thiab guanine.
Daim duab 01: DNA
Nyob hauv DNA helix, phosphate thiab qab zib moieties nyob sab nraum lub helix thaum lub hauv paus tseem nyob rau sab hauv ntawm lub helix. Ob txoj kab DNA khiav ntawm qhov sib txawv. Tsis tas li ntawd, DNA molecules nruj coil nrog histone proteins thiab ua cov xov zoo li cov qauv hu ua chromosomes hauv eukaryotes. Ib qho tseem ceeb ntawm DNA yog tias nws yog nws tus kheej-replicating, uas txhais tau tias nws muaj peev xwm replicate los yog luam ntawm nws tus kheej. Nws kuj muaj lub luag haujlwm tseem ceeb hauv kev tsim cov protein ntawm cov kab mob nyob.
cDNA yog dab tsi?
cDNA sawv cev rau DNA ntxiv. Nws yog ib daim ntawv ntawm DNA synthesized artificially los ntawm messenger RNA (mRNA) uas ua hauj lwm raws li ib tug template nyob rau hauv lub xub ntiag ntawm reverse transcriptase enzyme. Hauv feem ntau eukaryotes, genomic DNA muaj ntau cov noob uas muaj xws li exons thiab introns. Exons yog cov coding sequences thaum introns ua qhov tsis-coding ib feem ntawm genome. Feem ntau, thaum lub sij hawm gene qhia, kev nkag siab DNA ib ntus hloov mus rau hauv mRNA ib ntus ua ntej tsim cov protein. Thaum ua ib tug mRNA paub tab, ib tug splicing mechanism tshem tawm tag nrho cov intron sequences. Li no, mRNA paub tab tsis muaj introns lossis tsis-coding sequences.
Ntxiv mus, mRNA ntawm eukaryotic hlwb tuaj yeem raug muab rho tawm thiab ua kom huv huv thiaj li ua rau cDNA. Cov enzyme; thim rov qab transcriptase catalyzes cov synthesis ntawm cDNA los ntawm cov purified eukaryotic mRNA. Tom qab tsim cDNA los ntawm mRNA, lawv tuaj yeem raug cloned rau hauv cov kab mob hauv lub cell kom ua cDNA cov tsev qiv ntawv lossis siv tau los ua cov kev tshawb fawb heterologous.
Daim duab 02: cDNA
Feem ntau, cDNA muaj tus nqi loj hauv cloning ntawm eukaryotic noob hauv prokaryotes. Txij li thaum prokaryotes tsis muaj introns, lawv tsis muaj peev xwm excise intros los ntawm eukaryotic DNA thiab ua haujlwm mRNA. Yog li ntawd, ua ntej cloning tag nrho eukaryotic noob rau hauv prokaryotes, nws yog ib qho tsim nyog yuav tsum tshem tawm introns thiab ua cDNA los ntawm mRNA thiab clone rau hauv prokaryotes.
Dab tsi zoo sib xws ntawm DNA thiab cDNA?
- DNA thiab cDNA yog ob hom nucleic acids.
- Ob leeg muaj deoxyribonucleotide monomers.
- Tsis tas li, ob leeg muaj coding sequences ntawm noob.
Qhov txawv ntawm DNA thiab cDNA yog dab tsi?
DNA yog daim ntawv ntuj tsim ntawm nucleic acid thaum cDNA yog ib daim ntawv tsim tawm ntawm nucleic acid. Yog li, qhov no yog qhov sib txawv ntawm DNA thiab cDNA. Ntxiv mus, DNA sawv cev rau lub genome ntawm ntau yam kab mob nyob. Nws sau cov coding thiab tsis-coding sequences. Txawm li cas los xij, thaum ua mRNA, tag nrho cov intron sequences yog excised vim lawv tsis tseem ceeb rau kev tsim cov proteins. Yog li, mRNA sequences tsis muaj introns. Cov mRNA sequences ua raws li cov qauv thaum ua ke cDNA. Yog li, cDNA tsis muaj introns. Raws li, DNA muaj introns, tab sis cDNA tsis muaj introns. Peb tuaj yeem hais qhov no yog qhov sib txawv tseem ceeb ntawm DNA thiab cDNA.
Tsis tas li ntawd, vim cDNA tsuas muaj exons, cDNAs luv dua DNA. DNA muaj qee qhov introns uas hla ntau txhiab tus hauv paus khub. Yog li, qhov no kuj yog qhov sib txawv ntawm DNA thiab cDNA. Ntxiv mus, DNA ib txwm tshwm sim li ob-stranded helix thaum cDNA tshwm sim raws li ib leeg-stranded sequences. DNA polymerase yog lub enzyme uas catalyzes DNA synthesis los yog replication thaum rov qab transcriptase yog cov enzyme uas catalyzes cDNA synthesis nyob rau hauv lub lab.
Cov duab hauv qab no ntawm qhov sib txawv ntawm DNA thiab cDNA muab cov ntsiab lus ntxiv txog qhov sib txawv no.
Summary – DNA vs cDNA
DNA yog ib qho tseem ceeb polymer uas ua rau peb cov genome. Ntawm qhov tod tes, cDNA yog lwm hom DNA uas yog ib qho tseem ceeb los ua cov tsev qiv ntawv cDNA thiab tsim cov proteins uas tsis tshua qhia. mRNA yog siv los ua cDNA. Yog li, cDNA tsis muaj introns. Tab sis DNA muaj introns. Yog li, nws yog qhov sib txawv tseem ceeb ntawm DNA thiab cDNA. DNA muaj txiaj ntsig zoo rau kev tsim cov tsev qiv ntawv DNA genomic thaum cDNA muaj txiaj ntsig zoo rau kev tsim cov tsev qiv ntawv cDNA. Vim cDNA tsis muaj introns, cDNA luv dua DNA. Qhov tseem ceeb tshaj plaws, DNA yog ob-stranded thaum cDNA yog ib leeg-stranded. Qhov no qhia txog qhov sib txawv ntawm DNA thiab cDNA.
