Kukonza DNA kapena Kuyika mu Maselo
Pa mulingo wa mamolekyulu, moyo padziko lapansi umamangidwa pamaziko a chidziwitso cha majini chomwe chili mu mamolekyulu a DNA. DNA, kapena deoxyribonucleic acid, ndi polima yomwe imasunga malangizo a zamoyo ofunikira pakukula, kugwira ntchito, kukula, ndi kuberekana kwa zamoyo zonse. Ngakhale kuti DNA imapangidwa ndi mitundu inayi yokha ya ma nucleotide—adenine (A), thymine (T), cytosine (C), ndi guanine (G)—kapangidwe kawo mkati mwa maselo ndi kovuta kwambiri. Tiyeni tifufuze mwatsatanetsatane momwe DNA imakonzedwera, kapena kupakidwa, mkati mwa maselo.
Kapangidwe Koyambira ka DNA
DNA ili ndi mawonekedwe a double helix, omwe adapezeka ndi James Watson ndi Francis Crick mu 1953. Kapangidwe kameneka kamafanana ndi makwerero opindika, okhala ndi ma base pairs ngati ma stangs ndi sugar-phosphate backbone ngati handles. Ma base pairs pakati pa adenine ndi thymine, ndi cytosine ndi guanine, amalumikizidwa ndi ma hydrogen bonds, zomwe zimapangitsa kuti double helix ikhale yolimba.
Ma Histones ndi Nucleosomes
Mu nucleus ya selo ya eukaryotic, molekyulu ya DNA imatha kukhala yayitali mamita angapo ikatambasulidwa mokwanira. Kuyika molekyulu yayikuluyi mu nucleus yokhala ndi mainchesi ochepa okha m'mimba mwake kumafuna njira yopangira zinthu zapamwamba kwambiri. Chinthu chimodzi chofunikira kwambiri pakuyika DNA ndi mapuloteni otchedwa histones.
Ma Histone ndi mapuloteni oyambira okhala ndi ma amino acid lysine ndi arginine, zomwe zimawalola kuti azigwirizana bwino ndi DNA ya asidi. DNA imazungulira ma histone, ndikupanga mapangidwe otchedwa nucleosomes. Nucleosome iliyonse imakhala ndi ma base pairs pafupifupi 147 a DNA omwe amazungulira gulu la ma histones asanu ndi atatu, omwe amapanga gawo loyambira la chromatin. Unyolo wa ma nucleosome uwu umafanana ndi "chingwe cha mikanda" pansi pa maikulosikopu.
Chromatin ndi Chromosomu
Kuyika DNA kumapitilira m'magawo apamwamba, komwe ma nucleosome amakonzedwa kukhala kapangidwe kakang'ono komanso kolongosoka kotchedwa chromatin. Pali mitundu iwiri ikuluikulu ya chromatin: euchromatin ndi heterochromatin. Euchromatin ndi mawonekedwe otseguka komanso ogwira ntchito kwambiri, zomwe zikutanthauza kuti DNA m'madera awa imapezeka mosavuta ndi makina olembera. Mosiyana ndi zimenezi, heterochromatin ndi kakang'ono kwambiri ndipo nthawi zambiri imagwirizanitsidwa ndi DNA yosagwira ntchito.
Kukonza kwina kumapangika ma chromosome, omwe ndi kapangidwe kapamwamba kwambiri ka DNA, komwe kamawonekera panthawi yogawa maselo. Ma chromosome ndi mtundu wocheperako kwambiri wa DNA ndipo amatsimikizira kubwerezabwereza kwa DNA molondola popanda kutaya ziwalo zofunika panthawi ya mitosis ndi meiosis. Mwachitsanzo, anthu ali ndi ma chromosome 46 mu selo lililonse la thupi.
Lamulo Loyendetsera Kupaka DNA
Kuyika DNA si njira yokhazikika; imayenda mosiyanasiyana ndipo imakhudzidwa ndi zinthu zosiyanasiyana. Kusintha kwa histone, monga acetylation, methylation, phosphorylation, ndi ubiquitination, kungasinthe kuyanjana pakati pa DNA ndi histones, motero kumakhudza kuchuluka kwa chromatin ndi kupezeka kwa DNA kuti ilembedwe. Mwachitsanzo, histone acetylation nthawi zambiri imagwirizanitsidwa ndi euchromatin ndi active transcription, pomwe methylation imatha kutenga nawo gawo pakupanga heterochromatin.
Kuwonjezera pa ma histones, palinso mapuloteni okonzanso chromatin omwe amatha kusuntha, kuchepetsa, kapena kusintha malo a nucleosome, zomwe zimapangitsa kuti majini azitha kulowa mosavuta. Zonsezi zimagwira ntchito limodzi kuti ziwongolere bwino malamulo a DNA kuti akwaniritse zosowa zamaselo.
Kuyika DNA mu Prokaryotes
Mosiyana ndi ma eukaryote, mabakiteriya ndi zamoyo zina za prokaryote nthawi zambiri zimakhala ndi DNA yozungulira, osati yolunjika, ndipo sizimakhala ndi nucleus yolumikizidwa ndi nembanemba. Ngakhale kuti ndi yosavuta, kuyika DNA mu ma prokaryote n'kofunika kwambiri. Mu mabakiteriya, DNA imapangidwa ndi mapuloteni monga HU ndi IHF, omwe amalimbitsa supercoiling ndikuwongolera kapangidwe ka nucleoid.
Kufunika kwa Kuyika DNA
Kuyika DNA moyenera sikuti kumangokhudza kusunga chidziwitso cha majini okha, komanso kuwongolera magwiridwe antchito a majini. Malo ndi kuchuluka kwa chromatin kumatha kukhudza momwe majini amagwirira ntchito ndipo, motero, ndi gawo lofunika kwambiri pa kafukufuku wambiri mu epigenetics. Kuphunzira mitundu ya epigenetic kungapereke chidziwitso pa matenda osiyanasiyana, kuphatikizapo khansa ndi matenda obwera chifukwa cha chitukuko.
Mwachitsanzo, kusintha kwa mapangidwe a DNA kungayambitse kusakhazikika kwa majini, komwe kumalumikizidwa ndi kukula kwa khansa. Mankhwala omwe amayang'ana kusintha kwa histone kapena kapangidwe ka chromatin amasonyeza kuthekera kochiza matenda omwe amayamba chifukwa cha kusokonekera kwa malamulo a epigenetic.
Mapeto
Kukhazikitsa kapena kuyika DNA mkati mwa maselo ndi njira yovuta komanso yolongosoka yomwe imagwira ntchito yofunika kwambiri pa moyo. Kuyika DNA sikuti kumangokhudza kukhazikika kwa majini panthawi yogawa maselo komanso kumagwira ntchito ngati wolamulira wamkulu, kuwongolera majini omwe amafotokozedwa panthawi yoyenera komanso muyeso woyenera. Kumvetsetsa tsatanetsatane wa kuyika DNA kumapereka chidziwitso chakuya pa mfundo zoyambira za biology ya maselo ndikutsegulira njira yopangira njira zatsopano zochiritsira matenda a majini ndi epigenetic. Monga chimodzi mwa zinsinsi zodabwitsa kwambiri mu biology ya mamolekyulu, kafukufuku m'derali apitiliza kupereka zovuta zosangalatsa komanso mwayi kwa asayansi padziko lonse lapansi.
