Ntchito DNA ndi dongosolo lawo. Kodi DNA selo?

Nkhaniyi iyankha dongosolo la eukaryotic maselo, DNA, kapangidwe ndi ntchito ndi kuphunzira makampani zamoyo, wotchedwa cytology.

History of anapeza

Kodi yaikulu zikuluzikulu za phata selo, khromozomu ankagwidwa m'nthawi ya 19 ndi ofufuza angapo. A zamoyo Russian I. Chistyakov anaphunzira iwo pa mitosis (Chigawo khungu), German anatomist Heinrich Wilhelm Gottfried Von Waldeyer-Hartz anapeza iwo pa yokonza kukonzekera histological ndipo anaitana DNA, kuti kudetsa ng'ombe ayankhe mwamsanga nyumba izi mogwirizana ndi organic utoto magenta.

Fleming mwachidule umboni sayansi zimene ntchito imagwiridwa ndi DNA a maselo amene chokongoletsedwa phata.

Kapangidwe kunja DNA

Izi mapangidwe tosaoneka ili mu mtima - zofunika kwambiri maselo organelles akhale malo osungira ndi kufala kwa mudziwe cholowa cha chamoyo. DNA muli pophika wapadera - chromatin. Ndi chisokonezeko cha filaments chabwino - fibrils ndi granules. Kuyambira mankhwala pamaso, izi pawiri la liniya mamolekyulu DNA (40%) ndi mapuloteni yeniyeni histone.

Maofesi kuphatikizapo mapeputisayidi 8 ndi tizidutswa DNA ulusi wopota pa globules mapuloteni, monga coils otchedwa nucleosomes. Chiwembu deoxyribonucleic acid chimapanga 1,75 kusintha padziko kutsinde gawo ndipo ali mawonekedwe a ellipsoid za nanometers 10 m'litali ndi 5-6 m'lifupi. Pamaso pa nyumba iyi (DNA) mu pakati akutumikira monga taxonomic Mbali maselo eukaryotic. Ndi mu mawonekedwe a nucleosomes DNA ntchito ngati kusunga ndi kufala kwa makhalidwe chibadwa.

The kudalira wa Kapangidwe ka DNA ya gawo selo mkombero

Ngati khungu ndi mu interphase, amene amakhala ndi kukula kwambiri ndipo thupi, koma kupanda magawano, ndi DNA phata ali mawonekedwe a filaments woonda despiralizovannyh - chromonemata. Kawirikawiri zapiringizana, ndipo zowoneka kugawanitsa iwo mu nyumba osiyana zosatheka. Pa nthawi ya isanayambike magawano selo, yomwe ndi maselo somatic amatchedwa mitosis, ndi kugonana - meiosis, DNA kuyamba helical ndi thicken, kukhala yoonekera mu maso a.

Kaperekedwe ka bungwe DNA

Mayunitsi cha chibadwa - khromozomu, ikufotokoza mwatsatanetsatane sayansi chibadwa. Asayansi apeza kuti nucleosomal ulusi kupanga DNA-histone mapuloteni kupanga mwauzimu kuti poyamba. The wazolongedza wandiweyani dongosolo chromatin kumachitika chifukwa mapangidwe kuti apamwamba - solenoid. Iye bungwe ndi losindikizidwa mu ngakhale zovuta kwambiri youmba-koyilo. Zonsezi pamwambapa milingo mabungwe khromozomu ali pokonzekera maselo kugawikana.

Ilo liri mu mitotic mkombero structural unit wa chibadwa, wopangidwa mwa chibadwa munali DNA ali adzafupikitsidwa ndi unakhuthala poyerekeza ndi filiform chromonemata interphase nthawi pafupifupi 19 chikwi. Times. Izi yaying'ono mawonekedwe khromozomu ngale ntchito amene ali kusamutsa makhalidwe majini a chamoyo, okonzeka kugawanitsa somatic kapena nyongolosi maselo.

The kafukufuku wakapangidwe kazachilengedwe DNA ndi

DNA ntchito singalifotokoze kuphunzira zizindikiro zawo morphological kuti yabwino inachokera mu kuzungulira mitotic. Iwo anatsimikiza kuti mu gawo kupanga a interphase misa ya DNA mu selo kawiri chifukwa mukachipinda mwana popangidwa ndi kugawa ayenera yofanana mudziwe majini monga kholo pachiyambi. Izi zimatheka ndi ndondomeko kugawanika - kudziona anawaonjezera kuwirikiza kawiri DNA anachokera mwa enzyme DNA polymerase.

Zokonzekera cytological okonzeka pa nthawi ya metaphase wa mitosis mu mbewu kapena nyama maselo pansi pa maso bwino kuti aliyense khromozomu ndi zigawo ziwiri, wotchedwa chromatids. Mu magawo wotsatira wa mitosis - anaphase makamaka telophase - kupatulidwa zawo zonse zikachitika, umene aliyense chromatid amakhala khromozomu osiyana. Iwo limapangidwa mosalekeza ting'onoting'ono basi DNA, komanso lipids, mapuloteni acid ndi RNA. Maminolo zinthu muli magnesium ndi kashiamu ayoni.

Kuthandiza structural zinthu khromozomu

Kuti asakhale ndi vutoli ntchito mu selo kunachitika mu utumiki, mayunitsi cha chibadwa ali wapadera chipangizo - ndi constriction chachikulu (centromere), limene spiralizuetsya. Kuti ukugawa khromozomu pawiri, wotchedwa mapewa. Malinga ndi malo centromere ndi, khromozomu chibadwa wachinsinsi pa wofanana ngodya (metatsentrichnye) neravnoplechie (submetacentic) ndi akrotsentrichnye. Mu maphunziro apadera kaduka aakulu anapanga - kinetochores, amene litayamba ngati mapuloteni globules ili pa mbali zonse za centromere lapansi. Sami kinetochores zigwirizana ndi zigawo ziwiri: kukhudzana kunja ndi microfilaments (yamazinga spindle) kuwakonda.

Ndi kuchepetsa filaments (microfilaments) ndi mosamalitsa analamula yogawa chromatids kupanga khromozomu pakati pa maselo mwana wamkazi. Ena DNA ndi chimodzi kapena zingapo kaduka sekondale, amene sanapange nawo mitosis, chifukwa zimenezi zikhoza osatsagana ulusi spindle, koma ndi madera awa (kaduka sekondale) kupereka ulamuliro wa kaphatikizidwe nucleoli - organelles kuti ali ndi udindo mapangidwe ribosomes.

ndi karyotype Kodi

Mumadziwika geneticists Morgan, N. Koltsov, Sutton m'zaka za m'ma 20, mosamalitsa anaphunzira khromozomu kapangidwe ndi ntchito maselo somatic ndi nyongolosi - gametes. Iwo anapeza kuti iri yonse yochepetsetsa ya mitundu yonse ankaikira wina kuchuluka DNA ndi mawonekedwe enieni ndi kukula. Iwo adapempha kuchotsedwa DNA phata la maselo somatic otchedwa karyotype.

Mu mabuku karyotype otchuka kawirikawiri ukugwira akonzedwa kuti asakhale ndi vutoli. Ndipotu, si mfundo zofanana. Mwachitsanzo, karyotype anthu ndi DNA 46 mu mtima maselo somatic ndi zinaperekedwa mwa ambiri chilinganizo 2n. Koma maselo amenewa, monga hepatocytes (maselo chiwindi) ndi mtima ochepa, chromosomal awo womuyenerera amaimira monga 2n * 2 = 4n kapena 2n * 4 = 8n. Ndiko kuti, chiwerengero DNA maselo amenewa adzakhala oposa 46, ngakhale karyotype wa hepatocytes ndi 2n, ndiye pali 46 DNA.

topangira DNA maselo nyongolosi nthawi zonse kawiri zosakwana mu somatic (maselo a thupi) khalani iyi akutchedwa haploid ndipo amatchedwa N. Onse maselo ena mu thupi ndi ya 2n, wotchedwa diploid.

Morgan a khromozomu chiphunzitso cha cholowa

American zachibadwa Morgan anapeza lamulo la zogwirizana cholowa cha chibadwa, akafuna kutulukira zinthu pa mwakusakaniza ntchentche, ntchentche. Kafukufuku wake, ntchito ya DNA kugonana maselo anali kuphunzira. Morgan anasonyeza kuti chibadwa ili mu loyandikana loci wa khromozomu chomwecho, ambiri tinatengera pamodzi, i.e. zowalamulira pa. Ngati chibadwa ili khromozomu kutali Chrixitu, pakati mlongo DNA zotheka kuwoloka-pa - kugawa malo.

Mothandizidwa ndi kafukufuku wa Morgan, zinalengedwa mapu chibadwa, imene kuphunzira ntchito ya DNA ndi ntchito yaikulu uphungu majini kuthana ndi mavuto a pathologies zotheka DNA kapena majini kuchititsa matenda chawo anthu. Kufunika kwa mfundo za asayansi, n'zovuta Musaone.

M'nkhani ino takambirana kapangidwe ndi ntchito ya DNA, zomwe zimagwira selo.