Umsebenzi zofuzo kunye nesakhiwo zabo. Ntoni na zofuzo kwiseli?

Eli nqaku liza kuqwalasela ulwakhiwo lwe eukaryotic iiseli, ishishini biology zofuzo, isakhiwo umsebenzi zihlolisiswe, ebizwa cytology.

History of izovela

Ingaba yingxam engundoqo yeseli isiqalo, chromosome esafunyanwa ngenkulungwane ye-19 olwenziwe ngabenzi bophando eziliqela. A sebhayoloji Russian I. Chistyakov sasifunda ebudeni mitosis (division iseli), anatomist waseJamani uHeinrich UWilhelm Gottfried von Waldeyer-Hartz wafumanisa kubo ngethuba ekulungiseleleni ngamalungiselelo histological wabiza zofuzo, ukuba luyawudyobha namathole impendulo ekhawulezayo eziziseko yokusebenzisana organic ngedayi magenta.

Fleming kuthwa iinyaniso lwenzululwazi malunga umsebenzi lwenziwa yi zofuzo iiseli eziye zinokuhonjiswa isiqalo.

Isakhiwo sangaphandle zofuzo

Ezi owabumba ezincane ibekwe kwi eziba - i organelles zibalulekileyo iiseli kwaye ibe yindawo yokugcina kunye nokusasazwa kolwazi ilifa ephilayo. Zofuzo ibe yinto ekhethekileyo - chromatin. Kuyinto eyayiyingxubevange zixhobo ocoliweyo - fibrils kunye granules. Ngokwembono imichiza, le ambaxa kumgama owazisayo iimolekyuli DNA (40%) kunye neeproteni histone ethile.

Izakhiwo ezibandakanya peptides 8 iimolekyuli DNA vulu ejijekileyo kwi globules protein, njengoko jiko ebizwa nucleosomes. Plot deoxyribonucleic acid i-1,75 neziphithiphithi emhlabeni inxalenye umgqala kwaye emilise ellipsoid malunga neenanometer-10 ubude 5-6 ububanzi. Ubukho kwezi ziseko (zofuzo) kwi core isebenza njengoko bebubalaselisa taxonomic iiseli eukaryotic. Uthando ngohlobo nucleosomes zofuzo zisebenzayo njengamaqhosha ukugcinwa kunye nokusasazwa zofuzo.

Ukuxhomekeka le ubume zofuzo zeli nqanaba lomjikelo yeseli

Ukuba iseli leyo interphase, esibonakala kukukhula yayo kakhulu futhi umzimba, kodwa ukunqongophala kwisahlulo, le zofuzo ngumongo babe uhlobo kwayo ezingcakacileyo despiralizovannyh - chromonemata. Ngokuqhelekileyo ukuba uyahambelana, uze uzahlule abangaboniyo zibe zakhiwo zizimeleyo akunakwenzeka. Ngexesha kuqala kwicandelo iseli, olukuye kwiiseli somatic kuthiwa mitosis, kwaye ngesondo - meiosis, zofuzo baqala helical kwaye izokhula, sibonakale ngaphezulu ngemicroscope.

Amanqanaba mbutho zofuzo

Units yofuzo - chromosome, uhlolisisa iinkcukacha yemfuzo science. Izazinzulu ziye zafumanisa ukuba msonto nucleosomal eziquka iiproteni DNA-histone zenze uwele order kuqala. Ebezithunyelwe oxineneyo isakhiwo chromatin lwenzeka ngenxa ukuyilwa ucwangco eliphezulu - solenoid. Ulungiselela kwaye ivalelwa ezintsonkothileyo ngakumbi ezibhijeleyo-coil. Onke amanqanaba imibutho chromosome ngasentla ukulungiselela iiseli ukwahlula.

Kungenxa kwi mitotic kumjikelo unit noshowo kwimfuza, equka yemfuza eziqulathe DNA kukuncwina kwaye anquma kuthelekiswa filiform chromonemata ixesha interphase malunga ne-19 amawaka. Times. Oku compact fomu chromosome imisebenzi kernel eziya ukudlulisela zofuzo kumzimba, zilungele zahlule somatic okanye lwegciwane iiseli.

Le morphology ye zofuzo

zofuzo msebenzi kunokucaciswa ngokufundisisa iimpawu zazo morphological elihlolwa ngcono kuyofikwa kumjikelo mitotic. Oku kubonakaliswa ukuba kwinqanaba zokwenziwa of interphase ubunzima DNA yeseli kabini ngenxa yokuba kwiseli nganye intombi kuyilwa ngokwahlula, kufuneka umlinganiselo ofanayo zolwazi yemfuza njengoko umzali yokuqala. Oku kuphunyezwa inkqubo phindana - i-DNA self-kabini ethathwa yi-Polymerase DNA enzyme.

Xa amalungiselelo cytological ukulungiswa endaweni nomzuzu metaphase of mitosis yezityalo okanye isilwanyana iiseli ngemicroscope ngokucacileyo ukuba chromosome ngalinye libunjwa iinxalenye ezimbini, ebizwa chromatids. Xa kwizigaba ezilandelayo of mitosis - anaphase kwaye ingakumbi telophase - ngokwahlukana kwabo ngokupheleleyo kwenzeka, apho chromatid ngasinye siba a chromosome eyahlukileyo. Liquka ngokuqhubekayo ubunjwe DNA, kwakunye lipids, iiproteni acid kunye RNA. izinto Mineral iqulethe wemagniziyam kunye calcium ion.

Ukuxhasa zesakhiwo izinto chromosome

Ukuze umsebenzi chromosome esiseleni eyathatyathiswa ngokupheleleyo, ezi yunithi kwimfuza i isixhobo okukhethekile - constriction ephambili (centromere), nto leyo engazange spiralizuetsya. Loo nto yenza ukuba lo chromosome ibe ngamaqela amabini, ekuthiwa kwamagxa. Kuxhomekeka indawo centromere, zofuzo chromosome ezithathwa kwi neravnoplechie ngokulinganayo angle (metatsentrichnye) (submetacentic) kunye akrotsentrichnye. Kwimfundo ezizodwa constrictions zaseprayimari kwakhiwa - kinetochores, ezo globules iiproteins disk-ezifana ibekwe kumacala omabini le centromere. Sami kinetochores luqulathe izahlulo ezimbini: ukudibana lwangaphandle microfilaments (edibanise azinamsonto) nca kuzo.

Ngokunciphisa kwayo (microfilaments) lubekwa ngokungqongqo chromatids unikezelo equka i chromosome phakathi iiseli intombi. Ezinye zofuzo baye constrictions omnye okanye ngaphezulu sesekondari, ezo akazibandakanyi mitosis, ekubeni ezi ukujoyina othini umsonto, kodwa ke ezi ndawo (constrictions eziziisekondari) ukunika ulawulo Yindibanisela nucleoli - organelles ukuba banoxanduva ukuze kwakhiwe ribosomes.

Yintoni a karyotype

zofuzo eyaziwa Morgan, N. Koltsov, Sutton kule nkulungwane yama-20, ngocoselelo wafunda isakhiwo chromosome nomsebenzi kwizisele somatic kunye intsholongwane - gametes. Bafumanisa ukuba zonke iseli kuzo zonke iintlobo imifuziselo isixa esithile zofuzo ukanti imilo ethile kunye nobukhulu. Kuye kwacetyiswa ukuba wokuhlangana zofuzo kwinucleus iiseli somatic ekuthiwa karyotype.

In ethandwayo uncwadi karyotype idla ulinganiswa isethi chromosome. Enyanisweni, ayikho izinto ezifanayo. Umz, karyotype zabantu 46 zofuzo eziba iiseli somatic kwaye otyunjwe 2n ifomula jikelele. Kodwa iiseli, ezifana hepatocytes (iiseli kwesibindi) kufuneka nuclei ezimbalwa, inani labo chromosomal zibonakaliswe njenge 2n * 2 = 4n okanye 2n * 4 = 8n. Oko kukuthi, inani zofuzo ezi seli ziza kuba ngaphezu kwe-46, nangona karyotype of hepatocytes na 2n, ngoko kukho 46 zofuzo.

Inani zofuzo iiseli intsholongwane sisoloko izihlandlo ezibini ngaphantsi ngakumbi somatic (xa iiseli zomzimba), awumiselayo kuthiwa haploid yaye ibizwa ngokuba n. Zonke ezinye iiseli emzimbeni babe isethi 2n, ebizwa diploid.

chromosome theory Morgan ngayo ilifa

zofuzo American Morgan wafumanisa umthetho ilifa edityaniswe ngezakhi, sokuqhuba ii- phezu hybridization zempukane yeziqhamo, fruit. Ngophando lwakhe, umsebenzi zofuzo ngokwesini cell efunda. Morgan wabonisa ukuba genes ibekwe ngeso le chromosome efanayo eselumelwaneni, ikakhulu ilifa kunye, ngamanye iklatshi. Ukuba zofuzo zimi chromosome kude enye kwenye, phakathi udade zofuzo yokuwela-over kunokwenzeka - sites zokwabelana.

Ngoncedo lophando ka Morgan, zadalwa iimephu yemfuza, ngayo ukufunda umsebenzi zofuzo kwaye ukusetyenziswa kwazo kakhulu kwi ngeengcebiso ngezemvelo ukusombulula imiba ezimbi zofuzo okanye zofuzo kunokwenzeka ezibangela izifo njengelifa ebantwini. Ukubaluleka iziphetho izazinzulu, kunzima ukuba zazi.

Kweli nqaku, siye ingqalelo isakhiwo umsebenzi zofuzo, abasebenza wona kwiseli.