Reparation: Menene wannan? DNA gyara sunadaran

Reparation - a Rayayyen tantanin halitta na dukiya da za a magance da dama daga DNA lalacewa. A waje duniya akwai da yawa abubuwan da za su iya haifar da komowar canje-canje a cikin rayayyun kwayoyin halitta. Don adana su mutunci, don kauce wa pathological maye gurbi da kuma m da rayuwa, dole ne akwai wani tsarin na kai-dawo. Kamar yadda keta mutuncin kayyade abu na cell? Ka yi la'akari da wannan tambaya a cikin mafi daki-daki. Har ila yau, gano abin da suke da jiki ta gyara sunadaran da kuma yadda suke aiki.

Munanan a cikin DNA

Deoxyribonucleic acid kwayoyin iya karya a cikin shakka daga cikin biosynthesis kazalika a ƙarƙashin rinjayar abubuwa masu cutarwa. Daga cikin mummunan dalilai, musamman, sun hada da zazzabi ko da jiki ƙarfi daga daban-daban asalin. Idan karaya ya faru, da cell reparation aiwatar farawa. Kamar wancan fara sabuntawa na asali tsarin cikin jigidar halittar DNA. Domin reparation hadu takamaiman enzyme gidaje da suke ba a cikin sel. Tun da rashin iyawa na mutum Kwayoyin don gudanar da wasu dawo hade cuta. A kimiyya da cewa karatu da matakai na gyara, - shi ne ilmin halitta. A cikin horo da za'ayi da yawa gwaje-gwaje da kuma gwaje-gwajen, saboda abin da shi ya zama da sauki ga fahimtar dawo da tsarin. Ya kamata a lura da cewa sunadaran da DNA gyara ne da ban sha'awa sosai, kamar yadda tarihin samu da kuma nazarin wannan sabon abu. Abin da dalilai da taimako zuwa farkon na dawo? Don fara sama da tsari, shi ne cewa wajibi DNA stimulator shafi nama gyara. Mẽne ne, mafi bayyana a kasa.

Tarihi na samu

Wannan abin mamaki sabon abu fara nazarin American masanin kimiyya Kellner. A farko gagarumin samu a kan tafiya na bincike gyara ya zama irin wannan sabon abu kamar yadda photoreactivation. Wannan lokaci Sabis kira cũta raguwa sakamakon UV sakawa a iska mai guba da kuma post-bi suka ji rauni cell haske rafi na haske da bayyane bakan radiation.

"Light farfadowa da na'ura"

Daga baya karatu Kellner samu mai ma'ana ci gaba a cikin ayyukan American masana kimiyyar Setlou, Rupert kuma wasu wasu. Godiya ga aikin wannan kungiya na masana kimiyya da aka dogara tabbatar da cewa photoreactivation ne mai tsari da aka fara ta musamman abu - wani enzyme cewa catalyzes da tsakiyan nonon na taimain dimers. Sũ ne waɗanda suka, kamar yadda ya juya waje, aka kafa a cikin shakka daga cikin gwaje-gwajen a karkashin riskar hasken ultraviolet. Kamar wancan ne mai haske a bayyane haske kaddamar mataki na enzyme, wanda ciyar tsakiyan nonon na dimers da kuma mayar da asali yanayin lalace nama. A wannan yanayin da muke magana ne game da wani haske iri-iri na DNA gyara. Mun ayyana shi more fili. Za mu iya cewa da haske gyara - An tanadi asali fallasa zuwa haske bayan tsarin da DNA lalacewa. Duk da haka, wannan tsari yana tafiya ne ba kawai bayar da tasu gudunmuwar da kawar da rauni.

"Dark" dawo da

Wasu lokaci bayan bude da haske da aka gano duhu gyara. Wannan abu ya faru ba tare da wani sakamako na haske haskoki na gani bakan. Wannan tsirar da aka samu a lokacin da nazari ji na ƙwarai wasu kwayoyin zuwa hasken ultraviolet da ionizing radiation. Dark gyara DNA - da ikon na sel cire wani pathogenic canje-canje deoxyribonucleic acid. Amma dole ne a ce cewa wannan ba wani photochemical tsari, da bambanci ga haske dawo.

Ginshikai na "duhu" Damage cleanup

Abun Lura da kwayoyin nuna cewa bayan wani lokaci bayan da guda-celled kwayoyin samu wani yanki na ultraviolet, sakamakon wasu sassan na DNA da aka lalace, da cell shirya ta ciki matakai a wasu hanya. A sakamakon haka, da modified DNA ne kawai a yanki yanke daga sananniyar sarkar. A sakamakon sake cika gibba na amino acid dole abu. A wasu kalmomin, ta kai resynthesis na DNA. Opening na masana kimiyya irin wannan abu a matsayin duhu gyara nama - wannan shi ne wani mataki a binciko ban mamaki tsaron gida damar iya yin komai na dabba da mutum.

Ta yaya gyara tsarin

Gwaje-gwaje da Mun saukar da sunadaran da dawo da kuma sosai wanzuwar wannan ikon, da aka yi amfani da guda-celled kwayoyin. Amma gyara matakai ne muhimmi a rayuwa Kwayoyin na dabbobi da mutane. Wasu mutane su wahala daga xeroderma pigmentosum. Wannan cuta ne ya sa ta a rashin ikon na sel resynthesize lalace DNA. Xeroderma gaji. Ga abin da yake gyara tsarin? Hudu enzyme, wanda ya rike gyara tsari - a DNA helicase, -ekzonukleaza, polymerase da -ligaza. A farko daga cikin wadannan mahadi ne iya gane lalacewar da sarkar kwayoyin na deoxyribonucleic acid. Yana ba kawai gane, amma kuma cuts da sarkar a daidai wurin, to cire sashe na modified kwayoyin. Deposit kau ne da za'ayi tare da wani DNA exonuclease. Next, da kira na wani sabon yanki na deoxyribonucleic acid kwayoyin daga amino acid tare da wani ra'ayi zuwa gaba daya maye gurbin lalace kashi. To na karshe wannan hadaddun nazarin halittu hanyoyin yi tare da DNA ligase enzyme. Shi ne ke da alhakin abin da aka makala ga lalace rabo daga hada kwayoyin. Da zarar duk hudu enzymes sun aikata su aiki, cikin jigidar halittar DNA da aka gaba daya sabunta da kuma duk lalacewar da suka gabata. Wannan shi ne yadda smoothly aiki sunadaran cikin rayayyun tantani.

rarrabuwa

A wannan lokaci, malamai sun gano wadannan iri gyara tsarin. Suna kunna dangane daban-daban dalilai. Wadannan sun hada da:

1. Reactivation.
2. Recombination dawo.
3. Gyara na heteroduplexes.
4. Excision gyara.
5. A sauyin na ba-homologue iyakar DNA din.

All guda-celled kwayoyin da akalla uku enzymatic tsarin. Kowace daga cikinsu yana da ikon aiwatar da dawo da tsarin. Wadannan tsarin sun hada da: kai tsaye, excision da postreplicative. The iri uku DNA gyara da prokaryotes. Amma eukaryotes, shi ne a kawo musu kayan, ƙarin sunadaran, wanda ake kira Miss-mathe da SOS-gyara. Biology nazari a daki-daki, duk da irin wadannan kai-waraka daga cikin kwayoyin abu na sel.

Structure ƙarin sunadaran

Direct gyara - shi ne kalla rikitarwa hanyar yin kawar da canje-canje pathological a cikin DNA. Yana yana da za'ayi takamaiman enzymes. Godiya a gare su, da maido da tsarin da jigidar halittar DNA ne cikin sauri. Kullum, da aiwatar da fitowa a cikin mataki daya. Daya daga sama enzymes ne O6-methylguanine-DNA methyltransferase. Excision gyara tsarin - wannan shi ne nau'in kai-waraka daga deoxyribonucleic acid, wanda ya shafi yankan fitar da modified amino acid, kuma m maye su sake hada shafukan. Wannan tsari ne da za'ayi a dama, saukarwa. A lokacin postreplicative DNA gyara a cikin tsarin wannan kwayoyin za a iya kafa a rata darajar sarkar. Sa'an nan suka rufe tare da sa hannu na RecA gina jiki. Postreplicative gyara tsarin ne musamman a cewa ta aiwatar rasa lokaci ganewa na pathogenic canje-canje.

Wane ne alhakin da maida inji

Don kwanan wata, masana kimiyya san cewa irin wannan mai sauki dabba, kamar E. coli, yana da babu kasa da hamsin da kwayoyin halittu kai tsaye don gyara. Kowane gene tana da wani nauyi. Wadannan sun hada da: ganewa, kau, kira, da aka makala, da katin shaida na da sakamakon UV haskoki, da sauransu. Abin baƙin ciki, duk wani kwayoyin halitta, ciki har da wadanda suke da alhakin gyara matakai a cikin cell, hõre mutational canje-canje. Idan wannan ya faru, sai suka kaddamar da mafi m maye gurbi a cikin duk Kwayoyin na jiki.

The m lalacewar DNA

Kowace rana, da DNA na jikin mu Kwayoyin ne a hadarin lalacewar da kuma pathological canje-canje. Wannan yana yuwuwa ta muhalli dalilai kamar ultraviolet radiation, abinci Additives, sunadarai, zazzabi da tsakaitãwa, Magnetic filin, da yawa gajiyan cewa fara takamaiman matakai a cikin jiki, da kuma more. Idan DNA tsarin da aka karya, shi zai iya sa mai tsanani maye gurbi Kwayoyin da zai iya haifar da cutar daji a nan gaba. Wannan shi ne dalilin da ya sa jiki ne mai hadaddun na matakan magance irin raunin. Ko da enzymes iya komawa zuwa ga asali bayyanar DNA, gyara tsarin aiki fita don ci gaba da lalacewa zuwa m.

homologue recombination

Za mu fahimci abin da shi ne. Recombination ne musayar kayyade abu a cikin rata da fili kwayoyin na deoxyribonucleic acid. A cikin akwati inda akwai karyewar a cikin DNA, homologue recombination aiwatar fara. A lokacin shi ne musayar niƙaƙƙun biyu kwayoyin. Tare da wannan daidai mayar da asali tsarin deoxyribonucleic acid. shigar azzakari cikin farji na DNA zai iya faruwa a wasu lokuta. Ta hanyar aiwatar da recombination ne yiwu ga hade da biyu daban-daban abubuwa.

Ginshikai na dawo na jiki da kuma kiwon lafiya

A gyara - shi ne kafin na al'ada aiki na jiki. Ana hõre kullum da kuma hourly barazanar DNA lalacewa da kuma maye gurbi, kwayar tsarin adapts da kuma tsira. Wannan na faruwa ma saboda an kafa gyara tsarin. A rashin al'ada tsirar sa cutar maye gurbi da sauran munanan. Wadannan sun hada da wani iri-iri Pathology, Oncology, kuma ko da tsufa da kanta. Hereditary cututtuka saboda disturbances gyara iya kai ga tsanani m marurai da sauran munanan da kwayoyin. Yanzu gano wasu cututtuka da malfunctioning ne DNA gyara tsarin. Waɗannan su ne, misali, cututtuka kamar Cockayne ciwo, xeroderma, nonpolyposis ciwon daji ta hanji, Trichothiodystrophy da kuma wasu cancers.