Chemical Ukwakheka lezakhi zofuzo. Isakhiwo, umsebenzi kanye ngezigaba wama-chromosomes

Ngokuvamile ama-chromosome - ke izakhiwo nucleoprotein elise-nucleus amaseli eukaryotic. Baqhubeka cishe lonke ulwazi zofuzo, zinjalo umsebenzi wesitoreji yayo, ukudluliswa kanye nokusetshenziswa. Ngokuvamile ama-chromosome abonakala neze ngisho microscope ukukhanya, kodwa ungakwazi ngokucacile owabona izinkathi cell division ngesikhathi mitosis futhi meiosis.

Karyotype futhi Ama-chromosomes e imithetho

Karyotype iyona iqoqo zonke -chromosomes (diploid), kukhona yezinyoni. He is zinhlobo eqondene, okungukuthi kuhlukile kuye ngohlobo lwesimila ka izidalwa eziphilayo emhlabeni, lizinga simo esishubile kuqhathaniswa ongaphakeme, kodwa abanye abantu bangase babe nezici ezithile. Ngokwesibonelo, abameleli nabesifazane ezahlukene ngokuyisisekelo-chromosomes ezifanayo (autosomes), umehluko phakathi karyotypes ka nepheya elilodwa lezibuko wama-chromosomes - chromosome ubulili, noma-chromosome isesekeli.

Imigomo wama-chromosomes ilula: Inombolo yabo unomphela (kumaseli ukuphathwa kwabathintwayo ingaqukatha kuphela inombolo esiqinile wama-chromosomes, isibonelo, amakati - 38, esithelweni fly Drosophila melanogaster - 8, inkukhu - 78, futhi indoda 46).

Ngokuvamile ama-chromosome zibhangqwe, ngamunye wabo pair homologous, ezifanayo kuzo zonke izici, kuhlanganise ijamo kanye nosayizi. Iyahluka kuya kuphela umsuka: eyodwa - kuyise, elinye - kusukela kumama.

Ama-chromosomes e Homologous kukhona ngazimbili ngawodwana ngamunye ngazimbili lihlukile abanye hhayi kuphela ukubukeka - ukuma nosayizi - kodwa futhi indawo ukukhanya and bands amnyama.

Ukuqhubeka - omunye umthetho wama-chromosomes. DNA kabili amaseli ngaphambi division, okuholela a pair of udade chromatids. Ngamunye cell indodakazi ngemva division owamukela oyedwa chromatid, esenzelwa kusukela chromosome chromosome.

izakhi ezibalulekile

kwakhiwa chromosome, ogama isakhiwo lilula, lisuselwa molecule e-DNA kokuba obuphelele ezinkulu. Ubunjwe sebuningini amaqembu komugqa zofuzo. I-chromosome ngayinye has a centromere futhi telomere, ukufanisana Ukuqalwa iphuzu - ingabe izakhi ezidingekayo sokusebenza. Telomere zitholakala kweyoku amathiphu lezakhi zofuzo. Ngenxa yalezi zinkinga nezinye umsuka ukufanisana (olubizwa nangokuthi Ukuqalwa amasayithi), i-molecule ye-DNA kungenziwa ziphindaphindwe. Kwenzeka okufanayo centromere bukadadewabo ukunamathela DNA kuya mitotic lokuphotha division evumela ukuthi ukuhlakaza ngokunembile amaseli indodakazi phakathi kwenqubo mitosis.

mayelana amagciwane

Igama elithi "chromosome" ekuqaleni ezihlongozwayo njengoba ekubizweni izakhiwo ejwayelekile ka eukaryotic kumaseli, kodwa ososayensi ngokwethukela Ukhulume ezibangelwa amagciwane kanye ezibangelwa amagciwane chromosome. Ukwakheka, imisebenzi cishe okufanayo, ngakho DE Koryakov futhi I. F. Zhimulov bakholelwa ukuthi Sekube isikhathi eside umqondo kudingekile ukuba bandise futhi ichaze chromosome isakhiwo ehlanganisa a nucleic acid nokuba isitoreji umsebenzi, ukuqaliswa kanye ukudluliswa kolwazi zofuzo. Ngo eukaryotes, ama-chromosome eziqukethwe kuyi-nucleus, kanye plastids futhi mitochondria. Prokaryotes (non-senuzi) futhi aqukethe DNA, kodwa hhayi kuyi-nucleus yengqamuzana. Amagciwane-chromosomes isimo molecule RNA noma DNA, ise capsid. Kungakhathaliseki khona kule kuyi-nucleus yengqamuzana ka-chromosome kukhona izinto eziningi eziphilayo, metal ion kanye nezinye izinto eziningi.

Umlando yokutholakala

Ososayensi baye isishintshe kakhulu ukuya kuma-chromosome phambi wahlola. Bona achazwa ngokokuqala ngeminyaka yoma elidlule leminyaka: ahlukahlukene ababhali Ukhulume zawo izihloko, izincwadi kanye nocwaningo amaphepha, ngakho ukutholakala wama-chromosomes kuthiwa wenziwa ezahlukene abantu. Kulesi uhlu amagama I. D. Chistyakova, u-Alexander Schneider, O. Butschli E. Strasburger, nabanye abaningi, kodwa izazi eziningi zithi nyaka 1882 saziwa ngokuthi unyaka kuvulwa-chromosome, ngokuthi iphayona W. Fleming, anatomist German ngubani baqoqa ubuye uhlelembise lwati wama-chromosomes encwadini yakhe Zellsubstanz, Kern und Zelltheilung, okwenezela Imininingwane izifundo siqu osuvele ukhona. Igama elithi kakhulu efanayo liphakamisa 1888 uMnu Heinrich Wilhelm Gottfried von Waldeyer-Hartz histologist. chromosome ehunyushiwe kusho ngokoqobo "umzimba ezinemibala". Igama kungenxa yokuthi ukwakheka kwamakhemikhali wama-chromosomes kuyivumela kalula uxhumano nomsebenzisi udayi eziyisisekelo.

Ngo-1900, kwathiwa "balithola" imithetho Mendel, futhi ngokushesha kakhulu, phakathi neminyaka emibili, ososayensi baye baphetha ngokuthi chromosome ngesikhathi meiosis kanye kokukhulelwa izinqubo behave fana "izinhlayiya ufuzo" oziphatha ukuthi kwakuthiwa esesichaziwe. Ngo-1902, ngayodwana, noT Boveri W. Setton iye hypothesized ukuthi isakhiwo chromosome zazo ayaziwa, has a function ukuze adlulisele siphinde sigcine iminingwane zofuzo.

Drosophila nofuzo

Kwikota yokuqala yekhulu leminyaka elidlule kwaphawulwa isiqinisekiso yokulinga imibono ukuthi chromosome banendima zofuzo. ososayensi American T. Morgan, A. Sturtevant, C. Ziwumzila H. Muller sasebenza ucwaningo, okuyinto baye baba izinto kanye ngezigaba isakhiwo wama-chromosomes futhi umsebenzi wabo. Ukuhlolwa kwenziwa ku D.melanogaster, eyaziwa mhlawumbe zonke izithelo fly. Idatha etholwe zaba sisekelo lo theory chromosomal ufuzo, okuyinto efanele ngisho nanamuhla, ngemva kweminyaka cishe nekhulu. Ngokusho kwakhe, le-chromosome ehambisana ne zofuzo ulwazi, kanye izakhi zofuzo ehunyushelwe ku komugqa ukulandelana nakusolwa, kodwa amakhemikhali ukwakheka kanye morphology we-chromosomes kufundvwe ososayensi bethu izinsuku.

Ukuze umsebenzi T. Morgan waklonyeliswa uMklomelo KaNobel ngo Physiology noma Medicine ngo-1933.

Chemical Ukwakheka wama-chromosomes

It kungenziwa ngokufingqiwe ukuthi izinhlayiya eziyisisekelo zofuzo kuma-chromosome selivela Nucleo-amaprotheni eziyinkimbinkimbi. Ngemva kokutadisha inhlangano chemical lezakhi zofuzo ezisemangqamuzaneni eukaryotic, ososayensi ungasho ukuthi aqukethe ingxenye enkulu ye-DNA kanye amaprotheni ukuthi zakha eziyinkimbinkimbi Nucleo-iprotheni ebizwa ngokuthi i chromatin.

Amaphrotheni ngokufaka Ukwakheka wama-chromosomes, iyingxenye ebalulekile kwazo zonke izinto esizibonayo kuma-chromosome, cishe ngo-65% we isisindo ingqikithi izakhiwo siwela phezu kwakho. amaprotheni Chromosomal zihlukaniswe amaprotheni-non-histone futhi histone. Histones - sizindza lesicinile, ane-alikhali ngokwemvelo kubo kubangelwa khona lysine futhi argenina - kubalulekile amino acid.

Ukwakheka kwamakhemikhali takhi wama-chromosomes nhlobonhlobo. Histones kukhona imibango ezinhlanu: hl, H2A, H2B, H3 futhi H4. Zonke kodwa ingxenyenamba kuqala izinto eziningi okungenani zilingana ayatholakala amaseli ezinhlobo okuqondene ezincelisayo ephakeme. amaprotheni hl esingaphansi kwesigamu.

Synthesis histone kwenzeka polysomes cytoplasmic. Lokhu amaprotheni eziyisisekelo kokuba icala omuhle, ngenxa okungase exhunywe ngokuqinile ne molecule e-DNA, futhi ngaleyo ndlela ungayeki wokufundwayo okuvalelwe Imininingwane sitholwa njengefa. Lona indima lelawula histones, kodwa ngaphezu ke Ubuye umsebenzi kwesakhiwo, ngenxa okuyinto esikuthola enhlanganweni kwezendawo DNA kuma-chromosome.

I ejwayelekile amakhemikhali ukwakheka wama-chromosomes interphase futhi siqukethe non-histone amaprotheni, okuyinto yena, ezihlukaniswe engaphezu kwekhulu izingxenyana zaso. Kulolu chungechunge zihlanganisa enzyme obangela zamagama RNA, kanye enzyme ukuthi iqale ukulungisa kanye reduplication DNA. Kanye eziyisisekelo, esidi amaprotheni chromosomal abe umsebenzi kwesakhiwo zokulawula.

Nokho, ukwakheka amakhemikhali-chromosome akugcini: iprotheni futhi DNA RNA Ukwakheka samanje, metal ion, lipids futhi polysaccharides. RNA ngokwengxenye chromosomal samanje njengoba imikhiqizo transcriptional baye ukuthi okwamanje kwesokunxele endaweni zamagama.

Ngo metaphase

Morphological izici metaphase Ama-chromosomes e kanje: phakathi nengxenye yokuqala ka mitosis bona aqukethe ngazimbili bukadadewabo chromatids, okuyinto kuhlobene esifundeni centromere (constriction eyinhloko noma kinetochore) - kuyingxenye chromosome kuvamile kokubili chromatids. Ukwakheka kwamakhemikhali chromosome zishintsha. Ingxenye mitosis yesibili ebonakala ngokwahlukana chromatid, kulandele kumiswa owodwa balahleke indodakazi Ama-chromosomes e, okuyinto anikezwa amaseli indodakazi. Umbuzo ka-DNA kangakanani kuyingxenye chromosome metaphase, ezivamile ukuhlolwa eziphilayo futhi bekhungathekile abafundi. Esikhathini esiyiminyaka lokugcina interphase futhi prophase futhi metaphase Ama-chromosomes e dvuhromatidny, ngakho bamisa 2n4c ifomula.

ngezigaba wama-chromosomes

Isikhundla centromere futhi ubude nezingalo, okuyinto zitholakala nhlangothi zombili wama-chromosomes wakhe ihlukaniswa njengoba metacentric (L-alinganayo) uma centromere itholakala phakathi futhi submetacentric (neravnoplechie) uma centromere is saya komunye umkhawulo. Futhi, kukhona acrocentric, noma-chromosome induku emise (centromere baye elise cishe ngaso kakhulu ekupheleni) futhi iphuzu chromosome, okuthiwa i-lingakanani encane, ukuze cishe akunakwenzeka ukuthola ukuthi isimo sabo. Ngo telotsentricheskih Ama-chromosomes e nzima kakhulu ukunquma indawo eyinhloko constriction indawo.

compaction

Noma iyiphi iseli ukuphathwa kwabathintwayo iqukethe 23 ngazimbili wama-chromosomes, ngamunye esakhiwa DNA olulodwa. Ubude Imininingwane zishintshe 46 imayelana ezimbili amamitha! Lena angaphezu kwezigidi eziyizinkulungwane ezintathu base ngazimbili, futhi zingena zilingane iseli, chromosome ngesikhathi interphase cishe izakhamuzi zaseBosnia zifana ngisho ngesibonakhulu electron. Isizathu salokhu - inhlangano supramolecular wama-chromosomes, noma compaction. Esikhathini ukuthi ukwedlulela kuleso sigaba isigaba ezahlukene chromatin cell umjikelezo Ungashintsha inhlangano yayo.

Isakhiwo amakhemikhali ukwakheka kanye nesakhiwo interphase chromosome metaphase Ama-chromosomes e ososayensi kubhekwe ezahlukeneyo njengoba izakhiwo polar zazo ahlanganiswa ndawonye yi-ukuhwebelana mutual phakathi kwenqubo mitosis.

Izinga lokuqala emelelwa nucleosome compaction ngentambo, olubizwa nangokuthi "buhlalu yezinhlamvu". Isici usayizi - 10-11 NM, okuyinto ayikuvumeli ukuba ababheke ngesibonakhulu.

Chemical Ukwakheka wama-chromosomes inquma khona alolu lenhlangano: inikeza izinhlobo ezine histones - core amaprotheni (H2A, H2B, NC, N4). Bakha uqweqwe - umzimba yezinhlayiya amaprotheni ezimise washers. uqweqwe ngasinye siqukethe molecule ayisishiyagalombili (umusi molecule kusuka ngamunye histones).
Happens inhlangano DNA, it is spirally nilimaza amagxolo. Nge ngamunye contact umzimba ingxenye amaprotheni DNA has 146 nucleotide ngazimbili. Awekho ama-iqhaza kule ndawo yokuxhumana, ngokuthi linker, noma binders. ubungako bawo kuyahlukahluka, kodwa isilinganiso siyizinsuku ngazimbili 60 nucleotide (n. N.).

Ngokuthi nucleosome esifundeni DNA kokuba ubude 196 BP futhi kuhlanganisa amaprotheni cortex. Nokho nucleosome intambo ntambo-like ubuhlalu esifundeni hhayi equkethe cortex.

izingxenye ezinjalo okuyinto ukuhlukanisa kahle amaprotheni-non-histone, ngenxa yokubakhona nucleotide inqubo ethile abasakwazi nombala ngezikhawu eyizinkulungwane ezimbalwa base ngazimbili. Ukuba khona kwabo kubalulekile compaction obengeziwe chromatin.

nokupakisha obengeziwe chromatin

Chromatin fibril - compaction ezingeni lesibili - olubizwa nangokuthi ama-Solenoid, noma ezingeni nukleomernym. Usayizi 30 NM. Kuncike histone HI. Yena amaqembu up ukulandelana linker DNA, kanye soma angomakhelwane kanye "idonsa" ndawonye. Waba yini umphumela wesibindi inqubo kumiswa kuba okuningi isakhiwo compact, kepha efaniswe nesakhiwo Solenoid. fibril okunjalo, ngaphezu chromatin libizwa aphansi.

Balandela hronomerny ezingeni. Isici Usayizi ezingeni compaction - 300 nm. Kakade akukho olwengeziwe Helix ekwakhekeni, kodwa kukhiqizwa kokuhlanganisayo engu- ukuthi uqondane nenkundla replicon olulodwa futhi kuhlanganiswe esebenzisa non-histone (esidi)

On hromonemnom ezingeni (700 nm) loop bukhomba, ngisho chromatin kompaktiziruetsya ngaphezulu. imicu Bafunde wama-chromosomes kakade kubonakala isibonakhulu ukukhanya.

Chromosomal ungqimba (1400 NM) siyenzeka ngesikhathi metaphase.

Ukuguqula izakhi zofuzo kanye nendima yabo imithi

I kuguquka wama-chromosomes - into engavamile, kodwa angase abe degree ezahlukene kanye izindlela. Izinguquko efomini kwesakhiwo wama-chromosomes ngokuvamile esekelwe zokugwema ukuphuka kokuqala. Uma kukhona amakhefu e-chromosome, ngaleso sikhathi umzimba has ukukhiqiza ukuhlelwa kabusha yabo, umphumela kube ukuthi kukhona kuguquka chromosomal noma wayephazamisekile.

Phakathi crossover Ama-chromosomes e homologous bashintshisane izindawo ezifanele, futhi akuve kudabukisa zivamise ukwenzeka ngalesi sikhathi. Uma, ngesikhathi ukushintshana ukungalingani izingxenye Ukunqamula-phezu izakhi zofuzo, amaqembu amasha nokuxhumanisa.

izinhlobo yokwanda koshintsho

Kunezinhlobo eziningana izakhi zofuzo okuqondiswa esekelwe indlela lendabuko. Ngokuguqula izakhi ukuqoqwa livela ngenxa ukulahlekelwa isakhi sofuzo izingxenye. Uma izingxenye ezithile zofuzo abangu kabili - lokhu ukuphindwa. Phakathi kombhala we-chromosome phakathi unokungaxhumani ingxenye ijikeleziswa ngokusebenzisa 180 °.

Translocation ngokuthi ushintsho endaweni komunye chromosome kwenye, futhi uma ukufuduka kwenzeka phakathi Ama-chromosomes e-non-homologous, ngokuthi translocation okuhambisanayo, futhi uma isinqamu yadibana okufanayo chromosome kuguquka ngokuthi transposition. Phakathi translocation Robertsonian kwenzeka ubunye ku omunye ezimbili izakhiwo okungezona homologous.

Kukhona futhi ukuguquka kwezakhi zofuzo pericentric futhi paracentric.

RNA

Kuye esigabeni lapho cell, ukushintsha amakhemikhali ukwakheka, morphology, izici kanye nosayizi wama-chromosomes, kodwa izinhlayiya eziyisisekelo zofuzo iqukethe hhayi kuphela DNA ne-chromosomes e-nucleus.

Ribonucleic acid (RNA) - esinye isakhiwo iqhaza ku ukudluliswa kanye yokugcina ukwaziswa kwezakhi zofuzo.

Kube mRNA noma mRNA (-matrix, noma ulwazi), ke uhlanganyela zamagama amaprotheni ne izakhiwo oyifunayo. Ngenxa yalesi kubalulekile ukuthi indawo "ukwakhiwa" wathola "imiyalelo", okuyinto uzokutshela ngokulandelana kwama-amino acid kumele kufakwe iketango peptide. Lolu lwazi lenkulumo okubhalwe ukulandelana nucleotide we mRNA (mRNA). Ukulotshwa futhi ubizwa ngokuthi isithunywa RNA zamagama.

Inqubo ukufunda ulwazi kusuka DNA ingafaniswa uhlelo kukhompyutha. Okokuqala RNA polymerase umgqugquzeli kufanele ukuthola - ingxenye olukhethekile molecule ye-DNA, ephawula kokuqala esifundeni umbhalo. RNA polymerase sibopha ukuthi umgqugquzeli bese eqala unwinding eduze baphendukela-Helix DNA. Kuleli qophelo, amabili zingu-DNA Unqanyuliwe kulezi nomunye whereupon kumiswa enzyme mRNA iqala omunye wabo (kodogennoy ebhekene enzyme 3` ekupheleni). Ribonucleotides eqoqwe uchungechunge kokubusa complementarity kuya nucleotide of DNA ne antiparallel mayelana Strand isifanekiso DNA.

Inqubo umbhalo

Ngakho, njengoba siqhubeka engumucu DNA, enzyme ofunda ngokunembile yonke imininingwane, Ngokuqhubeka inqubo kuze kube ahlangane ukulandelana entsha eqondile ama-nucleotide. Ibizwa ngokuthi transkripktsii isinqamuli, futhi okubonisa ukuthi polymerase RNA kufanele uhlukane DNA Strand isifanekiso, futhi kusukela esanda kwemiqondo mRNA. Sum yezindawo umgqugquzeli kuya isinqamuli kuhlanganise eloba ingxenye okuthiwa umbhalo iyunithi - transcriptional.

Njengoba nje uhamba RNA polymerase kanye kodogennoy uchungechunge eloba izifunda owodwa balahleke le-DNA ehlanganisiwe futhi athathe isimo nge-double helix. mRNA Isungulwe ithwala ikhophi esiqondile idatha ukukopishwa kwesigaba DNA. Nucleotide ka mRNA ngamakhodi ukulandelana acid acid ziqoqwa abahamba ngabathathu kanye abizwa ngokuthi codons. codon ngamunye we mRNA elihambisana ethile acid acid.

Izakhiwo kanye umsebenzi zezakhi zofuzo

Isakhi ubhekwa i indivisible aphansi amayunithi obusebenzayo ufuzo-ezibonakalayo. It has uhlobo ingxenye DNA ufakwe isakhiwo okungenani olulodwa peptide.

Isakhi anezakhi ezithile, owokuqala babo - isenzo leyehlukene. Lokhu kusho ukuthi izakhi zofuzo ahlukene ukulawula ukuthuthukiswa izimpawu eyenziwe yaba eyasendaweni ngabanye.
the ukuqinisela komhiaba kunqunywa yokuthi isakhi sofuzo kuyinto ingashintshiwe ne yokudlulisela ngofuzo, ngaphandle-ke, kwakungekho wezakhi. Kule kusobala ukuthi isakhi sofuzo ayikwazi ukushintshwa phakathi nokuphila.

I ngokucacile isinyathelo ngenxa ukuthuthukiswa sici noma iqembu izici, kodwa izakhi zofuzo kungase kudingeke amaningi futhi isenzo - lokhu kubizwa ngokuthi pleiotropy.

Impahla sokuphuzisa senzo inquma elingakanani uphawu angagcina ufuzo ngenxa.

Futhi isici isimo allelic, okungukuthi, cishe kanye nazo zonke izakhi zofuzo kukhona alleles, ogama inombolo iqala ezimbili.