Yintoni chromatin: inkcazelo, isakhiwo kunye nokusebenza

izifundo kwemichiza izakhi - indlela ebalulekileyo ukufunda amacandelo zalo eziphambili - zofuzo zofuzo. Kweli nqaku siza kujonga ntoni na chromatin, ukufumana isakhiwo salo kunye umsebenzi kwiseli.

Esinazo - impahla ephambili kwezinto eziphilayo

Phakathi iinkqubo eziphambili okuluphawu eziphilayo ezihlala Umhlaba, uphefumla, isondlo, ukukhula, ukukhethwa ukuzala. Umsebenzi wokugqibela yeyona ibalulekileyo ukuze kulondolozwe ubomi emhlabeni. Njani ukuba ukukhumbula ukuba umthetho wokuqala enikwa nguThixo ukuba uAdam noEva yaba kulandelayo: ". Qhamani nande" Kwinqanaba iiseli umsebenzi okuvelisa lwenziwa nee-asidi acid (into usemthethweni zofuzo). Ezi zithinteli kuya kuxoxwa ngazo nto kuthethwa ngayo.

Kwakhona faka ukuba ukulondolozwa kunye nokusasazwa kolwazi yemfuza eyalo inzala indlela efanayo loo nto ixhomekeke kwinqanaba umbutho abantu, oko kukuthi ngokuba yintsholongwane kunye neentsholongwane, kwaye bonke abantu.

Yintoni na impahla yofuzo

Kweli phepha sifunda Isakhiwo chromatin kunye nemisebenzi apho zixhomekeke ngqo kwi lombutho iimolekyuli acid acid. Swiss inzululwazi Miescher ngo-1869 khompawundi zabonwa kwi eziba iiseli zamajoni omzimba, ubonise iimpawu asidi wababiza nukleina kuqala acids ke acid. Ngokwembono chemistry, oko macromolecular ezimbaxa - iipholima. Ezi monomers ke nucleotides kokuba isakhiwo zilandelayo: a purine okanye kwesiseko pyrimidine, nento pentose of orthophosphoric acid. Izazinzulu ziye zafumanisa ukuba iintlobo ezimbini nucleic ekhona kule iiseli: DNA kunye RNA. Bona complexed kunye iiproteni ukwenza compound zofuzo. Njengoko kwakunye iiproteni, nucleic kufuneka amanqanaba ezininzi lombutho lomhlaba.

Ngo-1953 i-Nobel Prize waba Watson kunye Crick ezifundekayo ubume DNA. It is a molecule eyakhiwa ngemixokelelwane emibini amaqhina oqhagamshelwano ngeentambo hydrogen evela phakathi iziseko nitrogen kwi kumgaqo complementarity (malunga isiseko thymine adenine ibekwe cytosine esahlukileyo - guanine). isakhiwo Chromatin nokusebenza kwawo izifundo, imolekyuli iqulathe deoxyribonucleic acid kunye sisimo ribonucleic ezahlukeneyo. Kulo mba, siza kuxubusha ngakumbi kwicandelo "Amanqanaba mbutho chromatin."

Kwasendaweni osisiqu yofuzo kwisisele

DNA langoku kwezi cytostructure nje undoqo, ngokunjalo organelles, ekwaziyo kwisahlulo - mitochondria kunye chloroplasts. Oku kungenxa yokuba ezi organelles enze imisebenzi ebalulekileyo esiseleni: kuyondelelaniswe ATP, kwaye kuyondelelaniswe glucose neoksijini uluhlu plant cells. organelles Synthetic womnye umzali kabini kwempilo. Ngenxa yoko, iiseli intombi kwi mitosis (hlula iiseli somatic) okanye meiosis (ukuyilwa isidoda kanye ova) kwenza ukuba izakhiwo iseli yokugcina efunekayo Nika iiseli izakhi kunye namandla.

Ribonucleic acid ibandakanya chain enye kwaye ubunzima esezantsi beemolekyuli kwe DNA. Wafumana apha nucleus kwaye hyaloplasm, kwaye iyinxenye ezininzi organelles iseli: ribosomes, mitochondria, reticulum endoplasmic, plastids. Chromatin kwezi organelles ezinxulumene histone protein kunye yinxalenye plasmids - setyhula evaliweyo iimolekyuli DNA.

isakhiwo Chromatin kunye

Ngoko siye saseka ukuba nucleic acid equlethwe kweziyobisi zofuzo - iiyunithi noshowo kwimfuza. chromatin phantsi kwemikroskopu na uhlobo granular okanye izakhiwo filamentous. Iqulathe, ngaphandle DNA, kwaye nkqu iimolekyuli RNA, kunye neeproteni bembonisa iipropati ezisisiseko kunye histones igama. Konke oku kungentla izakhiwo eziyinxalenye nucleosome. Bona afumaneka ngumongo kunye zofuzo kuthiwa fibrils (ngomsonto-solenoids). Eshwankathela zonke kungasentla, ungagqiba ukuba le chromatin. Le ezimbaxa nezintsonkothileyo ye asidi ideoxyribonucleic kunye neeproteni ezithile - histones. Bona, efana jiko, ngaba nxeba iimolekyuli DNA kabini-ndixakene ukuba ibe nucleosome.

Amanqanaba mbutho chromatin

izinto esinazo na isakhiwo eyahlukileyo, oko kuxhomekeke kwizinto ezininzi. Ngokomzekelo, yintoni isigaba sobomi kumjikelo nobunzi- iseli: ukulaba xesha (metoz okanye meiosis), okanye presynthetic eyenziweyo ngexesha interphase. Ukususela ngohlobo solenoid, okanye fibrils, njengoko alula, kukho ukugangatheka ngakumbi chromatin. Heterochromatin - urhulumente ashinyeneyo ngakumbi, senziwa iinxalenye intron le chromosome, nto leyo Ukuloba kunokwenzeka. Ngexesha iiseli ukuphumla - interphase, xa kungekho inkqubo division - karyoplasm heterochromatin ibekwe ngaphakathi kwinucleus peripherally, kufuphi ndizayo yayo. Uphawu imixholo nuclear kwisigaba postsynthetic kwenzeka kumjikelo wobomi iiseli, ngamanye kwangoko phambi hlula.

Yintoni egqibayo ukuba amafu of kwimfuza

Ukuqhubeka ukuhlola umbuzo othi "yintoni na chromatin," Abaphengululi bafumanisa ukuba kuxhomekeke iiproteni itywina-histone ukuba, kunye molecule DNA kunye RNA kwi nucleosome. Ziqulethe ntlobo ezine iiprotheni, ngokuba iinkomo kunye linker. Okwangoku le ukhutshelo (ukufunda ulwazi ukusuka sofuzo nge RNA) impahla yofuzo kakubi edidekile, yaye kuthiwa euchromatin.

Okwangoku ukwabiwa othile iimolekyuli DNA ezinxulumene iiproteni histone ukuba efundwayo. Umzekelo, abaphandi bafumanise ukuba chromatin ngeso ezahlukeneyo chromosome amanqanaba ezifanayo ezahlukeneyo amafu. Umzekelo, kwiindawo uncamathiselo kwi mitotic kwayo chromosome yokuluka ekuthiwa centromeres, oko esixineneyo ngaphezu amacandelo telomeric - ekupheleni ngeso.

Yemfuza-nabalawuli kunye chromatin

Ingcamango ummiselo umsebenzi gene, adalwe zemfuza French uYakobi Monod, kunika uluvo lokuba ubukho kwiindawo deoxyribonucleic acid, apho kungekho lwazi malunga isakhiwo protini. Senza onombono ingenalo novelwano - imisebenzi zolawulo. Ukuthiya nabalawuli yemfuza, ezi iindawo zofuzo ngokuqhelekileyo isakhiwo iiproteni yayo lube-histone. Chromatin, inkcazelo leyo lwaqhutywa yi yokulandelelanisa, ogama ezivulekileyo.

Izifundo phambili kwafunyaniswa ukuba kwezi ngeso zikwindawo ulandelelwano nucleotide ezithintela ukubambelela ukuya molekyuli DNA kwamasuntswana protein. izabelo ezinjalo ziquka ezi zofuzo zezi: activators bawo ehansery. Le ukugangatheka of chromatin kuzo phezulu, kwaye ubude kula macandelo avareji malunga 300 NM. Kukho indlela yokuqingqa chromatin zengqo- luvuliwe kwi nuclei ekwanti apho ukusetyenziswa enzyme DNA-Ase. Yena ngokukhawuleza uyazifohloza phantsi ngeso zofuzo, iiprotheni ningaswele-histone. Chromatin kwezi ndawo sele kuthiwa hypersensitive.

Indima kweziyobisi yofuzo

Izakhiwo kuquka DNA, RNA kunye iproteni ekuthiwa chromatin, ebandakanyekileyo kwiseli ontogeny kwaye ukutshintsha nokubunjwa kwayo kuxhomekeka kuhlobo inyama kunye nenqanaba yophuhliso ephilayo xa iyonke. Umz, iiseli epithelial ulusu zofuzo ezifana ehanser kunye nomthombo ukuvimbile iiprothini repressors, yaye ezi zofuzo iiseli secretory le epithelium wamathumbu yaye bakhuthele kummandla chromatin evulekileyo. Izazinzulu, zofuzo bafumanisa ukuba iqhezu DNA musa encoder iiproteni, olubalelwa kuka-95% zofuzo zabantu. Oku kuthetha ukuba ulawulo gene ungaphezulu kakhulu ngaphezu kwabo banoxanduva Yindibanisela peptides. Ukuqaliswa ubuchule ezifana chips DNA nolandelelwaniso ukuba ukufumanisa ukuba yintoni na chromatin, yaye ngenxa yoko, ukuze kuphononongwe ufuzo zabantu.

Studies of chromatin kubalulekile kwiindawo ezinjalo kwenzululwazi ezifana yemfuza zabantu genetics zonyango. Oku kuhambisana kabukhali kwakhula inqanaba kwisehlo sezifo zamafa - sofuzo efana kunye chromosome. ukubhaqwa ezi syndromes kwandisa ipesenteji Ingxelo eyakhayo unyango lwabo.