SamuwarSakandare da kuma makarantu

Mene ne reduplication na DNA? A tsari na DNA kwafi

Cikin jigidar halittar DNA - An located in chromosome tsarin. Daya chromosome ƙunshi guda kwayoyin kunsha na biyu strands. Reduplication na DNA - ne da canja wurin da bayanai bayan da kai-haifuwa na Sharhuna daga daya kwayoyin zuwa wani. Shi ne muhimmi a duka biyu DNA da RNA. Wannan labarin ya tattauna da DNA kwafi tsari.

Janar bayanai da kuma iri na DNA kira

An sani cewa Twisted yarn a cikin kwayoyin. Duk da haka, a lokacin da aiwatar da DNA kwafi ta fara, suka dispiralized, sa'an nan taku ajiye, da kuma a kan kowane sabon kwafin da aka hada. Bayan kammala akwai biyu gaba daya m kwayoyin, kowanne daga abin da a can ne da iyaye da kuma wani yaro thread. Wannan kira ne ake kira Semi-ra'ayin mazan jiya. DNA din ya motsa, yayin da sauran a guda centromere, kuma a karshe diverge kawai a lokacin da wannan centromere rabo aiwatar fara.

A wasu irin aka kira reparative kira. Ya, sabanin baya daya, ba a hade da wani cell mataki, amma yana farawa a taron na DNA lalacewa. Idan suna yi fadi da yawa-jere yanayi, da cell ƙarshe ya mutu. Duk da haka, idan lalacewa ne na gida, sa'an nan za ka iya mayar da su. Dangane da matsalar da za a mayar da ko ware biyu strands na DNA a lokaci daya. Wannan, kamar yadda shi ne ake kira, unscheduled kira ba ya dauki lokaci mai tsawo da kuma ba ya bukatar makamashi mai yawa.
Amma lokacin da akwai wani reduplication na DNA, sa'an nan ya ciyar makamashi mai yawa, abu, ya miƙa da tsawon da agogo.
Reduplication ne zuwa kashi uku lokaci:

  • qaddamarwa.
  • elongation.
  • ƙarshe.

Bari mu bincika da jerin DNA kwafi.

qaddamarwa

A adam DNA - 'yan dubun miliyoyin tushe nau'i-nau'i (da dabbobi suka lissafa kawai ɗari da tara). DNA reduplication fara a wurare da dama cikin sarkar ga wadannan dalilai. Kusan lokaci guda a cikin RNA kwafi ya auku, amma a cikin kira na DNA da aka dakatar a wasu daga cikin zaba wurare. Saboda haka, irin wannan tsari da wani isasshen adadin da abu accumulates a cikin cytoplasm na sel domin ya goyi bayan gene magana da salon salula aiki da ba a karya. A ra'ayi na wannan, da aiwatar da ya kamata faru da sauri. Watsa shirye-shirye a wannan lokaci da za'ayi, da kuma kwafi ba gudanar. Nazarin ya nuna cewa DNA reduplication faruwa sau daya a dama dubu maki - kananan yankunan da takamaiman nucleotide jerin. Sun hadu ne da musamman Mafarin sunadarai, wanda bi da bi ne ya koma da sauran enzymes daga DNA kwafi.

A DNA gutsure wanda aka hada da aka kira wani replicon. Yana farawa daga farko, kuma ya ƙare lokacin da enzyme terminates kwafi. Replicon ne m, kuma ma SUPPLiES dukan tsari na da kansa software.
A tsari na iya ba a fara daga duk maki a lokaci daya, wani wuri shi zai fara a baya, wani wuri - daga baya. Yana iya dauka wuri a daya ko a cikin biyu gaban kwatance. Abubuwan da suka faru ya faru a cikin wadannan domin a lokacin da image:

  • kwafi cokula masu yatsotsi.
  • RNA share fage.

kwafi cokali mai yatsu

Wannan bangare ya gabatar da wani tsari da a cikinsa a katse yarns an hada DNA deoxyribonucleic filaments. Banana haka samar da abin da ake kira ido na kwafi. A tsari ne da wadda ta gabãta daga wani adadin ayyuka:

  • saki daga dangane da histones a nucleosome - enzymes kamar DNA kwafi methylation, acetylation, kuma phosphorylation nuna sunadarai halayen da haifar a cikin sunadaran rasa su tabbatacce cajin cewa facilitates su saki.
  • despiralization - shi ne unwinding, wanda wajibi ne ga m kwata 'yanci na zaren.
  • karya hydrogen shaidu tsakanin DNA strands.
  • su bambanta rarrabuwar a cikin daban-daban bangarorin da kwayoyin.
  • kam faruwa ta amfani da SSB sunadaran.

RNA share fage

Kira daukawa wani enzyme kira DNA polymerase. Duk da haka, da za a fara kansa ya iya ba, don haka yin sauran enzymes - da RNA polymerase, wanda kuma ake kira RNA primers. Suna hada a layi daya strands na deoxyribonucleic a kan qa'ida ta complementarity. Saboda haka, qaddamarwa na RNA kira na biyu na ƙyallen maƙalawa, biyu primers kuma rabu da zunuban Yerobowam tsage baya DNA strands.

elongation

Wannan lokaci yana farawa daga nucleotide Bugu da kari kuma 3 'ƙarshen RNA-share fage, wanda daukawa ambata DNA polymerase. Yana dora wa na farko na biyu, na uku nucleotide, da sauransu. New thread tushe an haɗa ka da iyaye sarkar da hydrogen shaidu. An yi imani da cewa haduwar da yarn ne a cikin 5 '- 3'.
Ina da shi ya auku a gefen kwafi cokali mai yatsu, da kira faruwa ci gaba da kuma a lokaci guda lengthens. Saboda haka, wannan thread ake kira manyan ko manyan. Ta RNA share fage da aka daina kafa.

Duk da haka, a kan kishiyar tufka da iyaye DNA nucleotides ci gaba da shiga RNA share fage, da kuma deoxyribonucleic sarkar da aka hada a gaban shugabanci daga kwafi cokali mai yatsu. A wannan yanayin, shi ne ake kira jinkiri ko lagging.

A cikin lagging tufka kira auku a wani ɓaɓɓake, a cikinsa daya karshen rabo daga kira fara a wani wuri kusa da su ta amfani da cewa wannan RNA share fage. Kamar haka, akwai biyu jinkirta sarkar gutsure ana shiga DNA da RNA. Suna da ake kira Okazaki, niƙaƙƙun gaɓãɓuwa.

Sa'an nan duk abin da aka maimaita. Sa'an nan spliced wata kõmawa na Helix, hydrogen fashe sadarwa thread ga bangarorin, manyan sarkar tsawo a lagging hada wadannan gutsure RNA share fage, sa'ilin - Okazaki gutsure. Sa'an nan, a cikin wani jinkiri-tufka RNA primers an hallaka da DNA, niƙaƙƙun gaɓãɓuwa suna shiga cikin daya. Saboda haka wannan rangadi faruwa a lokaci guda:

  • da samuwar sabuwar RNA share fage;
  • kira na Okazaki, niƙaƙƙun gaɓãɓuwa.
  • Halakar RNA primers.
  • sake saduwa cikin wani guda kewaye.

ƙarshe

A tsari ya ci gaba, muddin biyu ba hadu da kwafi cokali mai yatsu, ko daya daga cikinsu zai zo ga ƙarshe na kwayoyin. Bayan taron, cokula masu yatsotsi DNA ya strands an shiga da enzyme. A cikin akwati, idan toshe aka koma zuwa karshen na DNA, DNA reduplication ƙare amfani musamman enzymes.

gyara

A wannan tsari, da muhimmiyar rawa da aka sanya wa iko (ko gyara) na kwafi. Don sanya kira na'am da duk hudu daban na nucleotides, da kuma bincike da DNA polymerase Pairing ance wadanda da ake bukata.

Da ake so nucleotide don su iya samar da hydrogen shaidu, kazalika da irin wannan nucleotide a kan template DNA tufka. Bugu da ƙari kuma, tsakanin sugar-phosphate kashin dole ne a wasu m nesa m zuwa uku zobba a cikin biyu sansanonin. Idan nucleotide ba ya hadu da wadannan bukatun, dangane ba zai faru.
Control ne da za'ayi kafin a kafa a cikin da'ira da kafin juya a kan m nucleotide. Bayan haka, dangane da kashin saharofosfata.

mutational canzawa

Ginshikai na DNA kwafi, duk da high yawan daidaito ne ko da yaushe disturbances a cikin filaments, wanda ake kira mafi yawa "gene maye gurbi." Game da dubu tushe nau'i-nau'i, akwai daya kuskure da cewa konvariantnaya kira reduplication.

Sai ya faru domin daban-daban dalilai. Alal misali, a high ko ma low yawa daga nucleotides deamination na saitosin, gaban mutagens a cikin kira na biyu. A wasu lokuta, da kuskure za a iya gyara ta hanyar gyara matakai a sauran gyara zama ba zai yiwu ba.

Idan lalacewa shafi barci sarari, wani kuskure ba zai yi tsanani sakamakon lokacin da akwai DNA kwafi tsari. Nucleotide jerin wani gene iya faruwa da ma'abota kuskure. Sa'an nan kuma ya ba shine al'amarin ba, da kuma wani mummunan sakamakon na iya zama kamar mutuwa da cell, da kuma mutuwar dukan kwayoyin. Ya kamata kuma a haifa tuna cewa gene maye gurbi ne bisa mutational canzawa, abin da ya sa cikin gene pool na plasticity.

methylation


A lokacin kira, ko nan da nan bayan da ta auku methylation sarƙoƙi. An yi imani da cewa wannan tsari ne wajibi ne ga wani mutum ya kafa chromosomes da kuma tsara gene kwafi. A wannan tsari kwayoyin na DNA da hidima ta kariya a kan yankan enzymes.

Similar articles

 

 

 

 

Trending Now

 

 

 

 

Newest

Copyright © 2018 ha.birmiss.com. Theme powered by WordPress.