Hanya na bazuwa: rarrabawa, haddasawa, misalai

Waɗanne canje-canje ana kiran su maras lokaci? Idan ka fassara wannan kalma a cikin harshe mai mahimmanci, to, waɗannan su ne kurakurai na halitta waɗanda suka taso a yayin hulɗa da kwayoyin halitta tare da yanayin ciki da / ko waje. Irin wannan maye gurbi yawanci bazuwar. Ana kiyaye su a cikin jinsin da kuma a wasu kwayoyin jiki.

Mawuyacin haddasa maye gurbi

Canji mai saurin yanayi zai iya faruwa a ƙarƙashin rinjayar sunadarai, radiation, ƙarƙashin rinjayar yanayin zafi ko rashin ƙarfi, iska mai sauƙi ko matsin lamba.

Kowace shekara, a matsakaici, mutum yana ɗaukar kimanin kashi ɗaya na goma na jerin radiation ionizing, wanda shine tushen radiation na halitta. Wannan adadi ya haɗa da radiation gamma na asalin duniya, iska mai hasken rana, da sake rediyowan abubuwa dake kwance a cikin kauri na ɓawon duniya kuma ya ragu a yanayin. Sakamakon binciken ya dogara ne a inda aka samo mutumin. Kashi na huɗu na maye gurbi wanda ba tare da bata lokaci ba ya faru daidai saboda wannan lamari.

Rikicin Ultraviolet, akasin gaskatawar da aka sani, yana taka muhimmiyar rawa a cikin hadarin DNA, tun da yake ba zai iya shiga zurfin zurfin jikin mutum ba. Amma fatar jiki sau da yawa na shan wahala daga rashin ƙarfi (melanoma da sauran cututtuka). Duk da haka, kwayoyin unicellular da ƙwayoyin ƙwayoyin cuta sunyi rikici a ƙarƙashin rinjayar hasken rana.

Ƙananan yanayin zafi ko ƙananan yanayi na iya haifar da canje-canje a cikin kwayoyin halitta.

Abubuwan da ke haifar da maye gurbin

Babban dalilai na maye gurbi wanda ba zai yiwu ba zai faru ne abubuwan da ke da ban sha'awa. Wadannan sun haɗa da samfurori na metabolism, kurakurai a tsarin aiwatarwa, sake gyara ko recombination, da sauransu.

1. Kuskuren sabuntawa:
   - ƙwararruwar kai tsaye da inversions na tushe na nitrogenous;
   - kuskuren kafawa na nucleotides saboda dalilai na DNA polymerase;
   - maye gurbin sunadaran nucleotides, misali, guanine-cytosine ta adenine-guanine.
2. Kuskuren dawowa:
   - maye gurbi a cikin kwayoyin da ke da alhakin gyaran sassa daban-daban na sarkar DNA bayan rushewa a ƙarƙashin rinjayar abubuwan da ke waje.
3. Matsaloli da recombination:
   - kasawa a cikin matakai na ƙetare-ƙasa a ƙarƙashin ɓangaren maiosis ko farfadowa da suka haifar da shigarwa da kuma cika bayanan.

Wadannan su ne ainihin dalilai da ke haifar da maye gurbin da ba'ayi ba. Sakamakon malfunctions zai iya kasancewa kunnawa na kwayoyin halitta, da kuma canji na hade mai sunadarai masu haɗari a cikin masu aiki da yawa wadanda suka shafi tsakiya daga tantanin halitta. Bugu da ƙari, akwai sauran matakan gini. Wadannan sun hada da maimaita jerin jerin nucleotides a kusa da shafin yanar gizo na sassauki na sarkar, gabanin ƙarin sassan DNA da suka kasance kamar tsari da jinsi, da kuma abubuwan da ke cikin kwayoyin halitta.

Harshen maye gurbin

Hanya na bazuwa ta samo asali ne daga tasiri na dukan abubuwan da ke sama, aiki tare ko daban a wani lokacin rayuwa. Akwai irin wannan abu a matsayin zubar da ciki na yarinyar da yarinyar DNA ta mahaifiyar. A sakamakon haka, ana sanya tsaka-tsalle na peptides sau da yawa, wanda ba za a iya shiga cikin jerin ba. Bayan cire DNA mai yawa daga sarkar 'yanta, za a iya sanya madogara biyu (share) da kuma sanyawa (duplications, insertions). Ana gyara canje-canje a cikin gajeren sassan cell division.

Rahoton da yawan maye gurbin da suka tashi sun dogara ne akan tsarin DNA na farko. Wasu masanan kimiyya sun gaskata cewa dukkanin jerin DNA suna da lahani, idan sun yi bend.

Mafi yawan maye gurbin da ba a yi ba

Menene mafi yawancin lokuta aka bayyana a cikin kwayoyin halitta na maye gurɓatattu? Misalan irin wadannan jihohi sune asarar magungunan nitrogenous da kuma cire amino acid. Sauran sharan sukari sun fi dacewa da su.

An tabbatar da cewa a yau, fiye da rabi na vertebrates suna da maye gurbin suturar cytosine. Bayan yaduwa, methylcytosine ya canza zuwa thymine. Kashewa na gaba na wannan ɓangaren yana maimaita kuskure ko share shi ko ninka shi kuma ya canza shi cikin sabon ɓangaren.

Wani dalili na yawan maye gurɓataccen lokaci ba shi ne babban adadin pseudogenes. Saboda wannan, a cikin tsarin na'ura mai nauyin na'ura mai yatsa, recombinations marasa daidaito na iya samar da su. Sakamakon wannan shine sake dawowa a cikin jinsin, juyawa da sau biyu na kowane nau'in nucleotide.

Alamar polymerase na mutagenesis

Bisa ga wannan samfurin, maye gurbi ba tare da bata lokaci ba sakamakon sakamakon kurakuran kwayoyin halittar DNA. A karo na farko irin wannan samfurin ya gabatar da Bresler. Ya nuna cewa maye gurbi ne saboda gaskiyar cewa polymerases a wasu lokuta sun hada da nucleotides mara kyau a cikin jerin.

Shekaru daga baya, bayan binciken da gwaje-gwajen da yawa, an yarda da wannan ra'ayi kuma an yarda da shi a cikin kimiyya. An samo wasu hukumomi wanda ya ba da izini ga masana kimiyya su sarrafa da kuma tsara maye gurbi ta hanyar yada wasu yankuna na DNA zuwa radiation radiation. Alal misali, an gano cewa adrenine an gina shi ne a gaban wani sau uku mai lalacewa.

Alamar mai kulawa da ƙwayar cuta

Wata ka'idar da ta bayyana rashin daidaituwa da maye gurbi wanda Watson da Crick (masu bincike na tsarin DNA) suka nuna. Sun nuna cewa ilimin kimiyya ya dangana ne akan yiwuwar wasu magungunan DNA don canzawa zuwa siffofin tautomeric wanda zai canza hanyar da aka haɗa da asusun.

Bayan wallafawa, an gabatar da hypothesis. An gano sababbin siffofin nucleotides bayan watsawa tare da ultraviolet. Wannan ya ba masana kimiyya sabuwar damar yin bincike. Kimiyyar zamani na ci gaba da yin gardama game da muhimmancin siffofin tautomeric a cikin kwayoyin halitta ba tare da batawa ba kuma tasirinsa akan yawan maye gurbin da aka gano.

Sauran misalai

Hakanan yiwuwar maye gurbi ba zai yiwu ba idan DNA DNA polymerases ba a gane shi ba daga kwayoyin nucleic acid. Poltayev da mawallafin marubuta sunyi bayanin tsarin da ke tabbatar da ka'idar hadin kai a cikin jerin sunayen kwayoyin DNA. Wannan samfurin ya ba da izinin nazarin ka'idodin bayyanar da kwayoyin halitta. Masana kimiyya sun bayyana binciken su ta hanyar gaskiyar cewa babban dalilin canzawa a cikin tsarin DNA shine kira ne na nau'i-nau'i marasa nau'in nucleotides.

Sun nuna cewa zubar da asali daga tushen asali ne saboda zubar da sassan DNA. Wannan yana haifar da sauyawa a cikin tsarin sitosin zuwa kamine ko uracil. Saboda irin wannan maye gurbin, an kafa nau'i-nau'i na nucleotides marasa daidaituwa. Sabili da haka, a lokacin da ake biyowa na gaba, akwai sauyi (maimaita maye gurbin ginshiƙan nucleotide).

Ƙayyadewa na maye gurbin: kwatsam

Akwai bambanci daban-daban na maye gurbi dangane da abin da ma'auni ke bisa su. Akwai rabuwa bisa ga yanayin sauyawa a cikin aikin ginin:

- hypomorphic (gurguntaccen kwayoyin halitta sun haɗa da sunadarai kaɗan, amma suna kama da ainihin asali);
- amorphous (jigon halittar gaba daya rasa ayyukansa);
- antimorphous (kwayar canzawa ta canza canjin da yake wakilta);
- neomorphic (sabon alamu sun bayyana).

Amma haɓakawa yafi kowa, wanda ya raba dukkan maye gurbin da tsarin da ba zai iya faɗi ba. Allocate:

1. Tsarin halittu. Wadannan sun hada da polyploidy, wato, halittar kwayar halitta tare da sau uku ko fiye da chromosome kafa, da kuma sake sakewa - adadin chromosomes a cikin kwayar halitta ba nau'i na haɗin ba.
2. Sauyawa da kyamosome. Akwai manyan canje-canje a wasu sassan chromosomes. Bambanci tsakanin asarar bayanai (sharewa), kwafin kwafi (kwafi), sauyawa a daidaitawar nauyin nucleotide (inversion), da kuma canja wurin yankunan chromosome zuwa wani wuri (fassarar).
3. Sauyawa na mutun. Mafi yawan maye gurbi. A cikin siginar DNA, an maye gurbin ɗakunan bayanan nitrogen.

Sakamakon maye gurbin

Hanyoyin maye gurbi suna haifar da ciwon ciwace-ciwacen ƙwayoyin cuta, ƙwayoyin ruɗuwa, dysfunctions na gabobin da kyallen takalma na mutane da dabbobi. Idan kwayar da aka canzawa ta kasance a cikin babban kwayar halitta, to, tare da matsayi mai girma na yiwuwa zai halaka ta apoptosis (wanda aka tsara mutuwa ta jiki). Jiki yana sarrafa tsarin kiyaye kayan kwayoyin halitta kuma ta hanyar tsarin rigakafin kawar da dukkanin kwayoyin lalacewar da ta yiwu.

A wasu lokuta, daga daruruwan dubban, T-lymphocytes ba su da lokaci don gane tsarin da ya shafi, kuma yana ba da clone na sel wanda ya hada da kwayar halitta. Tsarin kwayoyin halitta yana da sauran ayyuka, yana haifar da abubuwa masu guba kuma yana mummunan rinjayar tsarin jiki na jiki.

Idan maye gurbi bai faru ba a cikin haɗari amma a cikin kwayar jima'i, to, za a yi canje-canje a cikin zuriya. Ana nuna su ta hanyar maganin cututtuka na kwayoyin halitta, da nakasa, da nakasa da kuma haduwa.

Hanyoyin maye gurbi: muhimmancin

A wasu lokuta, maye gurbi mara amfani mara amfani marar amfani na bayawa yana da amfani don daidaitawa a sabon yanayin rayuwa. Wannan yana wakiltar maye gurbi a matsayin ma'auni na zabin yanayi. Dabbobi, tsuntsaye da kwari suna da canza launin kyama, daidai da wurin zama, don kare kansu daga magunguna. Amma idan mazauninsu ya bambanta, to, tare da taimakon maye gurbin yanayi yana kokarin kare nau'in daga nau'i. A cikin sabon yanayin, wanda ya fi dacewa ya tsira kuma ya canja wannan damar ga wasu.

Mutuwa zai iya faruwa a cikin sassa marasa aiki na kwayar halitta, sa'an nan kuma babu canjin canji a cikin phenotype. Don gano "rashin lafiya" yana yiwuwa ne kawai tare da taimakon takamaiman karatun. Wannan wajibi ne don nazarin asalin nau'in dabbobin da suka danganci da kuma tsara taswirar su.

Matsalar spontaneity na maye gurbin

A cikin karkara na karni na ƙarshe, akwai ka'idar cewa maye gurbin da aka haifar da ta hanyar tasirin abubuwan waje kuma ya taimaka musu su daidaita. Domin gwada wannan ka'idar, an fara gwaji na musamman da kuma hanyar yin maimaitawa.

Hanyar ta kunshi gaskiyar cewa an shuka karamin kwayoyin nau'in nau'i daya a jikin jarraba gwaji kuma bayan da yawa an hana su maganin rigakafi. Wasu daga cikin kwayoyin halitta sun rayu, kuma an canja su zuwa sabon yanayi. Daidaita kwayoyin cutar daga gwajin gwaji daban-daban sun nuna cewa juriya ta bayyana ta hanyar kwatsam, kafin da bayan bayanan kwayoyin.

Hanyar maimaitawa shi ne cewa an sanya microorganisms zuwa abin da ya tsere, sa'an nan kuma a sauya shi zuwa wasu kafofin watsa labaru daban-daban lokaci guda. Sabbin yankuna sun kasance da al'adun da aka bi da su tare da kwayoyin halitta. A sakamakon haka, kwayoyin kwayoyin cuta a jikin gwaji daban-daban sun tsira a kan sassan guda biyu.