Kurongeka kweDNA kana Kurongedza muMasero
Padanho remamorekuru, hupenyu panyika hwakavakirwa pahwaro hweruzivo rwemajini rwuri mumamorekuru eDNA. DNA, kana kuti deoxyribonucleic acid, ipolymer inochengeta mirairo yehupenyu inokosha pakukura, kushanda, kukura, uye kuberekana kwezvinhu zvipenyu zvose. Kunyange zvazvo DNA yakaumbwa nemarudzi mana chete enucleotides—adenine (A), thymine (T), cytosine (C), uye guanine (G)—kurongeka kwavo mukati memasero kwakaoma zvikuru. Ngationgororei zvakadzama kuti DNA yakarongwa sei, kana kuti yakarongwa sei, mukati memasero.
Chimiro Chekutanga cheDNA
DNA ine chimiro che double helix, chakawanikwa naJames Watson naFrancis Crick muna 1953. Chimiro ichi chakafanana nemanera akakombama, ane ma base pairs sematanho uye musana we sugar-phosphate semubato. Ma base pairs ari pakati pe adenine ne thymine, uye cytosine ne guanine, akabatanidzwa ne hydrogen bonds, zvichipa kugadzikana kune double helix.
Histones uye Nucleosomes
Mukati memasero eeukaryotic, molekyuru yeDNA inogona kureba mamita akati wandei kana yakatambanudzwa zvizere. Kuisa molekyuru iyi hombe munucleus ine dhayamita shoma chete kunoda nzira yekurongedza yakanakisa. Chimwe chinhu chakakosha pakurongedza DNA mapuroteni anonzi mahistone.
MaHistones mapuroteni ekutanga akapfuma muamino acids lysine nearginine, zvichivabvumira kushanda zvakanaka neDNA ine acidic. DNA yakapoteredzwa nemahistones, ichiumba maumbirwo anozivikanwa senucleosomes. Nucleosome yega yega ine ma base pairs angangoita 147 eDNA akapoteredzwa neboka rema histones masere, zvichigadzira unit yekutanga ye chromatin. Iyi cheni ye nucleosomes yakafanana ne "tambo yemabhidhi" pasi pe microscope.
Chromatin nemaChromosomes
Kurongedza DNA kunoenderera mberi kuburikidza nemazinga akakwirira, uko nucleosomes dzakarongwa kuita chimiro chakamanikana uye chakarongeka chinonzi chromatin. Kune marudzi maviri makuru echromatin: euchromatin neheterochromatin. Euchromatin ndiyo fomu yakavhurika uye inoshanda mukunyora, zvichireva kuti DNA munzvimbo idzi inowanikwa zviri nyore nemichina yekunyora. Kusiyana neizvi, heterochromatin yakamanikana uye inowanzobatanidzwa neDNA isingashandi mukunyora.
Kurongeka kwakawedzerwa kunoumba ma chromosome, maumbirwo epamusoro-soro eDNA, anoonekwa panguva yekupatsanurwa kwemasero. Ma chromosome ndiwo rudzi rwakanyanya kusimba rweDNA uye anovimbisa kudzokororwa kweDNA kwakarurama pasina kurasikirwa nezvikamu zvakakosha panguva ye mitosis ne meiosis. Semuenzaniso, vanhu vane ma chromosome makumi mana nematanhatu musero rega rega remuviri.
Mutemo weKurongedza DNA
Kurongedza DNA hakusi maitiro asingachinji; kunoshanduka uye kunokonzerwa nezvinhu zvakasiyana-siyana. Kugadziriswa kweHistone, senge acetylation, methylation, phosphorylation, uye ubiquitination, kunogona kuchinja kusangana pakati peDNA nehistones, nokudaro kuchikanganisa huwandu hwechromatin uye kugona kweDNA kunyorwa. Semuenzaniso, histone acetylation inowanzobatanidzwa ne euchromatin uye active transcription, nepo methylation ichigona kuita basa mukuumbwa kweheterochromatin.
Pamusoro pema histones, kunewo mapuroteni ekugadzirisa chromatin anogona kufambisa, kuderedza, kana kugadzirisa nzvimbo dze nucleosome, zvichiwedzera kugadzirisa kugona kwemajini. Zvese izvi zvinoshanda pamwe chete kuti zvivandudze mutemo weDNA kuti usvike pazvinodiwa nemasero anochinja-chinja.
Kurongedza DNA muProkaryotes
Kusiyana nemaeukaryotes, mabhakitiriya nezvimwe zvipenyu zveprokaryotic zvinowanzova neDNA yakatenderera, kwete yakatsetseka, uye hazvina nucleus yakasungwa nemembrane. Kunyangwe zviri nyore, kurongedza DNA mumaprokaryotes hakuna kukosha zvakanyanya. Mumabhakitiriya, DNA inoumbwa nerubatsiro rwemapuroteni akadai seHU neIHF, ayo anodzikamisa supercoiling uye anotonga chimiro chenucleoid.
Kukosha kweDNA Packaging
Kurongedza DNA zvakanaka hakusi kungochengetedza ruzivo rwemajini chete, asiwo kudzora mashandiro emajini. Nzvimbo uye huwandu hwechromatin zvinogona kukanganisa kuratidzwa kwemajini uye, nekudaro, ndiyo inonyanya kutsvagurudzwa mu epigenetics. Kudzidza ma epigenetic models kunogona kupa ruzivo nezvezvirwere zvakasiyana-siyana zvehutano, kusanganisira kenza uye matambudziko ekukura.
Semuenzaniso, shanduko mumapakeji eDNA inogona kutungamira mukugadzirwa kwemajini kusina kujairika, izvo zvine chekuita nekukura kwegomarara. Marapirwo anotarisana nekuchinja kwehistone kana chimiro chechromatin anoratidza kugona kurapa zvirwere zvinokonzerwa nekusagadzikana kwemutemo we epigenetic.
Mhedziso
Kurongeka kana kurongedza DNA mukati memasero inzira yakaoma uye yakadzama inoita basa guru muhupenyu. Kurongedza DNA hakungobatsiri chete pakugadzikana kwemajini panguva yekupatsanurwa kwemasero asiwo kunoshanda semutongi mukuru, kutonga kuti majini api anoratidzwa panguva yakakodzera uye nehuwandu hwakakodzera. Kunzwisisa ruzivo rwekurongedza DNA kunopa ruzivo rwakadzama pamusoro penheyo dzebiology yemasero uye kunovhura nzira yekuvandudzwa kwemishonga mitsva yezvirwere zvemajini ne epigenetic. Sechimwe chezvinhu zvinoshamisa zvikuru mubiology yemakemikari, tsvakiridzo munzvimbo iyi icharamba ichipa matambudziko anonakidza nemikana kune masayendisiti pasi rese.
