Qhov Tseem Ceeb - DNA vs Histone Methylation
Methylation yog cov txheej txheem lom neeg los ntawm cov pab pawg methyl (CH 3) ntxiv rau cov molecule thiab hloov kho los txhim kho lossis txwv nws txoj haujlwm. Hauv cov ntsiab lus ntawm noob caj noob ces, methylation tuaj yeem tshwm sim ntawm ob theem: DNA methylation thiab histone methylation. Ob txheej txheem ncaj qha cuam tshuam rau cov txheej txheem transcription ntawm cov noob thiab tswj kev qhia ntawm cov noob. Hauv DNA methylation, ib pab pawg methyl ntxiv rau cytosine lossis adenine nucleotide ntawm DNA molecule, uas hloov kho ob lub nucleotide residues txhawm rau txhawm rau ua haujlwm ntawm cov noob hloov pauv thiab tiv thaiv kev qhia ntawm cov noob. Hauv histone methylation, ib pawg methyl ntxiv rau cov amino acids ntawm histone protein. Qhov no yog qhov txawv ntawm DNA thiab histone methylation.
DNA Methylation yog dab tsi?
Cov txheej txheem epigenetic uas cov pab pawg methyl ntxiv rau DNA molecule thiaj li tswj tau qhov kev qhia ntawm cov noob hu ua DNA methylation. DNA methylation tsis hloov qhov sib lawv liag ntawm DNA tab sis cuam tshuam rau kev ua ntawm DNA. Cov txheej txheem no yog qhov tsim nyog rau kev txhim kho ib txwm muaj nyob hauv lub cev thiab txuas nrog ntau cov txheej txheem tseem ceeb ntawm lub cev uas suav nrog kev khaws cia ntawm chromosome stability, embryonic txoj kev loj hlob, carcinogenesis, kev laus, x-chromosome inactivation thiab repression ntawm transposable ntsiab. Thaum cov txheej txheem methylation tshwm sim ntawm thaj chaw txhawb nqa ntawm cov noob, nws koom nrog kev tsim txom ntawm cov noob hloov pauv. DNA molecule muaj ib tug ua ke ntawm plaub (04) nucleotides: adenine, guanine, thymine thiab cytosine. Tawm ntawm plaub lub hauv paus ntawm DNA, adenine thiab cytosine tuaj yeem ua methylated. Thaum lub sij hawm DNA methylation, ib pawg methyl ntxiv rau 5 thcarbon ntawm cytosine nplhaib los hloov cytosine puag rau 5-methylcytosine. Cov txheej txheem cytosine residue hloov kho no yog catalyzed los ntawm ib qho enzyme hu ua DNA methyltransferase. Ib qho hloov kho cytosine puag yog tam sim no nyob ib sab ntawm lub hauv paus guanine. Yog li ntawd, nyob rau hauv ob chav helical qauv ntawm DNA, hloov cytosine bases yog tam sim no diagonally rau ib leeg ntawm opposite DNA strands.
Daim duab 01: DNA methylation
Adenine methylation yog txheej txheem muaj nyob rau hauv cov nroj tsuag, kab mob thiab tsiaj txhu. DNA methylation ntawm cov nroj tsuag thiab lwm yam kab mob muaj nyob rau hauv peb qhov sib txawv sib txawv cov ntsiab lus. Lawv yog CG, CHH thiab CHG, qhov H yog hais txog Adenine, Thymine lossis Cytosine.
Histone Methylation yog dab tsi?
Histone yog cov protein uas ua rau cov nucleosome, uas yog cov qauv ntawm cov chromosome eukaryotic. Lub nucleosome qhwv ib ncig ntawm DNA ob helix uas ua rau tsim cov chromosomes. Histone methylation yog txheej txheem uas hloov methyl pawg mus rau cov amino acids ntawm histone protein. Lub DNA raug mob nyob ib ncig ntawm ob pawg ntawm cov proteins uas zoo ib yam hu ua protein octamer. Plaub hom histone proteins (ob daim ntawv theej txhua) koom nrog hauv kev tsim no yog H2A, H2b, H3 thiab H4. Cov plaub hom histone proteins muaj xws li tus Tsov tus tw. Cov tail extensions ua raws li lub hom phiaj ntawm kev hloov kho nucleosome los ntawm methylation. Kev ua kom thiab inactivation ntawm DNA nyob ntawm tus Tsov tus tw residue uas yog methylated thiab nws lub peev xwm ntawm methylation.
Daim duab 02: Histone Methylation
Methylation ntawm histones ncaj qha cuam tshuam rau kev hloov pauv ntawm cov noob. Nws muaj peev xwm los nce lossis txo cov txheej txheem, uas nyob ntawm seb hom amino acids nyob rau hauv cov protein histone uas yuav tsum tau methylated thiab ntawm cov methyl pawg txuas. Cov txheej txheem kev hloov pauv tau txhim kho vim qee qhov kev cuam tshuam methylation uas ua rau tsis muaj zog ntawm cov ntawv cog lus tam sim no ntawm histone tails thiab DNA. Qhov no tshwm sim los ntawm kev ua kom cov txheej txheem uncoiling ntawm DNA los ntawm nucleosome uas pab txhawb kev sib cuam tshuam ntawm cov khoom hloov pauv, polymerases thiab DNA. Cov txheej txheem no yog ib kauj ruam tseem ceeb hauv kev tswj hwm ntawm cov noob qhia thiab ua rau muaj kev qhia ntawm cov noob sib txawv los ntawm cov hlwb sib txawv. Methylation ntawm histone proteins tshwm sim ntawm cov seem seem, feem ntau ntawm lysine (K) residues ntawm histone tails ntawm H3 thiab H4 thiab kuj ntawm arginine (R) thiab. Lysine thiab arginine yog cov amino acids. Histone methyltransferase yog ib qho enzyme uas siv los hloov methyl pawg rau lysine thiab arginine, cov seem seem ntawm H3 thiab H4 histone proteins.
Dab tsi zoo sib xws ntawm DNA thiab Histone Methylation?
Nyob rau hauv ob txoj kev, methyl pawg tau ntxiv
Qhov txawv ntawm DNA thiab Histone Methylation yog dab tsi?
DNA vs Histone Methylation |
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| Ntxiv ntawm pawg methyl rau cytosine lossis adenine nucleotides ntawm DNA molecule hu ua DNA methylation. | Kev hloov ntawm methyl pawg mus rau cov amino acids ntawm cov proteins histone hu ua histone methylation. |
| Catalyst | |
| Qhov sib ntxiv ntawm methyl pawg rau cov cytosine residue yog catalyzed los ntawm DNA methyltransferase. | Cov tshuaj tiv thaiv uas hloov cov pawg methyl mus rau cov amino acid ntawm histone protein yog catalyzed los ntawm histone methyltransferase. |
| Yog DNA methylation tshwm sim hauv thaj tsam txhawb nqa ntawm cov noob, nws txwv kev hloov pauv ntawm cov noob thiab tiv thaiv cov noob qhia. | Yog tias histone methylation tshwm sim, nws txhawb nqa qhov tsis sib xws ntawm DNA los ntawm cov ntaub qhwv nucleosome thiab pab txhawb kev sib cuam tshuam ntawm cov txheej txheem hloov pauv thiab polymerases nrog DNA thiab txhim kho cov txheej txheem gene. |
Summary – DNA vs Histone Methylation
Methylation yog txheej txheem los ntawm cov pab pawg methyl ntxiv rau cov molecule zoo li DNA lossis protein. Hauv cov ntsiab lus ntawm cov noob caj noob ces, DNA methylation thiab histone methylation ncaj qha cuam tshuam rau kev tswj hwm ntawm cov noob caj noob ces thiab tswj cov noob qhia ntawm cov hlwb. Cov tshuaj tiv thaiv DNA methylation thiab histone methylation yog catalyzed los ntawm DNA thiab histone methyltransferase, feem. Thaum ib pab pawg methyl ntxiv rau DNA, nws yog lub npe hu ua DNA methylation thiab thaum ib pab pawg methyl ntxiv rau cov amino acids ntawm histone protein, nws yog hu ua histone methylation. Qhov no yog qhov txawv ntawm DNA thiab histone methylation.
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