Kwezakhi okuzenzekelayo: Ukuhlelwa, oonobangela, imizekelo

Yintoni ekuthiwa wezakhi kulogo? Ukuba gama wotshintsho ngolwimi ekhoyo, kuba iziphoso zemvelo ezenzeka ngexesha impefumlelwano genetic material ukusuka kwindawo zangaphakathi kunye / okanye nabangaphandle. Ezo zofuzo kuvame ngengozi. Bona iqatshelwe ngesondo, kunye nakwezinye iiseli zomzimba.

Ezisuka ngaphandle kubangela ukuguquka

ukuguquka avele inokwenzeka phantsi kwempembelelo kweekhemikhali, imitha, phantsi intshukumo ye amaqondo obushushu aphezulu okanye asezantsi, umoya obhityileyo okanye uxinzelelo oluphezulu.

Nyaka ngamnye, umntu avareji lutyabula malunga yeshumi elinye-Sinovuyo ionizing imitha leyo eyenza i-radiation imvelaphi yendalo. Eli nani liquka Ukungagqibeki imitha evela emhlabeni core, umoya solar, izinto radioactive, lulele Ebubanzini kuqweqwe songanyibilikisswa emoyeni. Ithamo ngenxa kwakhona kuxhomekeke apho abantu. Ikota zonke ziye zidityaniswe eyenzekayo nandzu kule inkalo.

Eyingozi radiation, echasene uluvo othandwayo, idlala indima encinci ebangela umonakalo DNA, njengoko unako ukungena nzulu ngokwaneleyo emzimbeni womntu. Ke isikhumba kudla uphethwe elihlala livelile ngokugqithiseleyo (wolusu kunye nezinye ngumhlaza). Noko ke, izinto eziphilayo olunye-ezineseli kunye iintsholongwane inokuzitshintsha xa libekwe kwindawo enelanga.

Too amaqondo obushushu aphezulu okanye asezantsi kakhulu kunokubangela utshintsho impahla yemfuza.

Kwedijithali kubangela ukuguquka

Izizathu eziphambili ngenxa apho ukuguquka ezizenzekelayo kwenzeke, zezona zinto iqala. Ezi ziquka icala-iimveliso emzimbeni, iimpazamo ngexesha phindana, ukulungiswa kunye recombination, kunye nabanye.

1. Ukwehluleka ukuphindaphindeka:
   - ukuguquka ezizenzekelayo inversions neziseko nitrogen;
   - kokufaka engafanelekanga ze nucleotides yezono polymerases DNA;
   - chemical ukufaka nucleotides, ezifana guanine-cytosine ukuya adenine-guanine.
2. Imposiso yokwakha:
   - ukuguquka kule zofuzo ezibangela ukuba kutywinwe iintanda izigaba yalo mngxilo DNA emva kwekhefu phantsi kwempembelelo iimeko zangaphandle.
3. Iingxaki ne recombination:
   - ukusilela kwinkqubo crossover ngexesha meiosis kunye mitosis japan imvula kunye nokwandiswa evela iziseko.

Ezi zinto ziphambili ezibangela zofuzo ezikhululekileyo. Izinto ezibangela ukusilela kunokuba ukuvula yemfuza mutator kwakunye nokuguqulwa iikhemikali elikhuselekileyo metabolites esebenzayo ngakumbi echaphazela ngumongo iseli. Ukongeza, kukho kwakhona izinto zokwakha. Ezi ziquka ulandelelwano nucleotide phinda kufuphi wesekethe hlengiso site, ubukho kwimimandla ezongezelelweyo DNA ezifanayo ngenye isakhiwo kwigenome, ngokunjalo izinto ezihambisekayo zofuzo.

Pathogenesis zofuzo

kwezakhi okuzenzekelayo kwenzeka ngenxa iimpembelelo zonke ezi zinto ezichaphazela, kunye okanye zodwa kwixesha elithile lobomi esiseleni. Kukho ezifana simanga njenge ezihambayo lokukhwela ukungathobeli sokuncedisa kunye imisonto DNA koomama. Ngenxa yoko, badla wabumba ephambuka peptide, ezo nako ukudibanisa ngokwaneleyo ngokulandelelana. Emva kokususa iinxalenye okungeyomfuneko ye-DNA chain ephambuka oluncedisayo okwazi resected (nokususwa) kwaye ludityaniswe (duplications, oko kufakelweyo). utshintsho lwamaJuda iyalungiswa yindlela ayile zilandelayo sisahlula cell.

Isantya Inani yemfuza zixhomekeke kubume ephambili DNA. Ezinye izazinzulu zikholelwa ukuba ngokupheleleyo zonke ulandelelwano DNA ye mutagenic ukuba zakha bend.

Eyona ukuguquka zixhaphakileyo kulogo

Yintoni amaninzi wabonakaliswa zofuzo izakhi ezizenzekelayo? Imizekelo yeemeko ezinjalo - ilahleko iziseko nitrogen uwasusa acid. Ingakumbi sensitive kubo babonwa kwiintsalela cytosine.

Oku kubonakaliswa ukuba namhlanje ngaphezu kwesiqingatha ekuyo sele kuguquka zeentsalela cytosine. Emva deamination methylcytosine kutshintshwe thymine. Landela-up kweli candelo ephinda imposiso okanye lisusa okanye kabini kunye eziguqulayo ukuya ukuqhekeka entsha.

Enye imbangela izakhi rhoqo ezizenzekelayo kuthathwa inani elikhulu pseudogenes. Ngenxa yale nto ke, inkqubo meiosis nga kuyilwa recombination ukungalingani homologous. Oku kukhokelela hlengahlengiso kwi imfuza amagophe ngamnye kunye ulandelelwano buya nucleotide.

model Polymerase mutagenesis

Ngokwale ndlela, kwiDNA ezikhululekileyo zibangelwa random iimpazamo molekyuli synthesizing DNA. Kuba okokuqala kule ndlela sele kuqhutywa yi Bresler. Wacebisa ukuba ukuziguqula kwenzeka ngenxa yokuba kwezinye iimeko, le polymerase lifakwa ukulandelelana nucleotides nekomplimentarnye.

Kwiminyaka kamva, emva iimvavanyo elide kunye amalinge, le mbono sele sivunyiwe kwaye zamkelwa kwi lesayensi. nokuba kukho kwasuswa imithetho ethile ezivumela izazinzulu ukulawula kunye ukuguquka ngqo kukungakhuseleki ukuba eyingozi ziqwempu DNA ethile. Ngoko ke, umzekelo, wafumana ukuba phambi triplet eyonakeleyo ayeba adenine.

mutagenesis imodeli Tautomeric

Enye ingcamango echaza wezakhi ezizenzekelayo neyenziweyo yaphakanyiswa yi Watson kunye Crick (discoverers ngesakhiwo DNA). Bamcebisa ukuba mutagenesis ngokusekelwe ekukwazini ethile isiseko DNA atshintshelwe iifom tautomeric, ukutshintsha iziseko indlela udibaniso.

Emva kokupapashwa hypothesis sele ayenziwa. iintlobo ezintsha nucleotides zabonwa emva zokukhanya nokukhanya eyingozi. Oku kwanika oosonzululwazi amathuba zophando entsha. Iinzululwazi zale mihla nangoku axoxe indima kweefomu tautomeric kwi mutagenesis ezizenzekelayo kunye nefuthe layo kwinani zofuzo ekhethiwe.

nezinye

kwezakhi okuzenzekelayo kungaba kukwaphula ingqalelo DNA polymerase asidi acid. Poltaevym et al yacaciswa mechanism ukuba unyanzelisa complementarity siseko kwi Yindibanisela iimolekyuli DNA abaxhasi. Le modeli wavumela ukuba afunde iipateni kwizihlandlo of mutagenesis ezizenzekelayo. Abaphandi wachaza ifunyanwe ukuba esona sizathu siphambili ukutshintsha isakhiwo DNA amagama i ngababini isiseko non-eziphefumlelweyo.

Bamcebisa ukuba isizathu nokudubula kwenzeka ngenxa deamination ye DNA. Oku kukhokelela yokutshintsha cytosine ukuya thymine okanye uracil. Ngenxa yezi ukuziguqula kwakheka iperi nucleotides ezingahambelaniyo. Ngoko ke, ebudeni phindana elandelayo kwenzeka utshintsho (nucleobases replacement dot).

Ucalulo izakhi: ezizenzekelayo

Kukho ukuhlelwa ezahlukeneyo izakhi ngokuxhomekeke kuhlobo njengenqobo amanga ezingundoqo zabo. Kukho iCandelo umlinganiswa utshintsho zofuzo:

- hypomorphic (mutated alleles nokulungelelanisa protein, kodwa ezifanayo original);
- amorphous (sofuzo walahlekelwa ngokupheleleyo umsebenzi wayo);
- antimorfnye (sofuzo mutated umva umqondiso leyo);
- neomorfnye (kukho iinkalo ezintsha).

Kodwa ulwahlulohlulo eqhelekileyo ngakumbi leyo yahlula zonke izakhi ngokomlinganiselo isakhiwo bume. ihloniphekile:

1. ukuguquka lofuzo. Ezi ziquka polyploidy, okt ukuyilwa zofuzo kunye abathathu kunye iseti zofuzo, kunye aneuploidy - inani zofuzo kwi zofuzo akukho iphindaphindeke le haploid.
2. Chromosomal kuguquka. Kukho ngokutsha okubalulekileyo amaqhosha zofuzo. Ukwahlula ukulahleka kwengcaciso (ukususwa), kabini yayo (uphinda-phindo), utshintsho kwi yokuqhelwaniswa ulandelelwano nucleotide (inversion), kwakunye transfer nakwiziza zofuzo kwenye indawo (kwazo).
3. yofuzo. Eyona zofuzo zixhaphakileyo. I-chain DNA ithathwa iziseko eziliqela random nitrogen.

Imiphumela izakhi

ukuguquka okuzenzekelayo - ebangela izifo zokugcina nangezilonda, kwekhono amalungu kunye nezihlunu abantu kunye nezilwanyana. Ukuba iseli mutated sibekwe ngendlela ephilayo enkulu multicellular, kokukhona kusenokwenzeka ukuba iza kutshatyalaliswa kwasungulwa apoptosis (ukufa kweeseli). Iqumrhu elawula inkqubo yolondolozo ngezixhobo yemfuza, yaye ngoncedo amajoni omzimba ubani ayeke zonke iiseli kunokwenzeka yonakele.

Komnye Kwimeko amakhulu amawaka T-lymphocyte abanalo ixesha ukuchonga isakhiwo abachaphazelekayo, kwaye inika iiseli clone ukuba nazo ziqulathe sofuzo mutated. iseli yeMetro sele eminye imisebenzi, sivelisa izinto eziyityhefu kwaye ichaphazele imeko jikelele umzimba.

Ukuba akukho ukuguquka yenzeka yeseli somatic kunye intsholongwane, utshintsho iqatshelwe inzala. Abazibonakalisayo ukungaqheleki iziphene ngamalungu, sengozini, ukuphazamiseka pathways, kunye nezifo zokugcina.

ukuguquka ahlale: Ixabiso

Kwezinye iimeko, kwabonakala ngaphambili ukuguquka ephuthileyo kunokuba luncedo ukuba ziziqhelanise nobomi obutsha. Oku kuguquka njengenyathelo ngokukhethwa zendalo. Izilwanyana, iintaka nezinambuzane sifihle kombala ehambelana ukuya kwindawo yokuhlala ukuze bazikhusele kumarhamncwa. Kodwa ukuba ukutshintsha kwendawo yabo, ngoko usebenzisa zizama indalo uzama ukukhusela iintlobo ekutshabalaleni. Phantsi kweemeko ezintsha nexoxo liyazigxumela kwaye bokukhupha ubuchule kwabanye.

Le kuguquka kungaba kwenzeka kwiindawo ezingezo-active zofuzo, uze ubone utshintsho lo phenotype waphawula. Fumana i "breakage" kunokwenzeka kuphela ngokusebenzisa izifundo ezithile. Kuyimfuneko ukuba ukufunda imvelaphi yezinto eziphilayo enxulumene izilwanyana kunye nokulungisa iimephu zabo yemfuza.

Ingxaki izakhi ezizenzekelayo

Xa novalo zenkulungwane lokugqibela kwakukho ingcamango ukuba guquko yabangela kuphela yimiba bangaphandle ukubanceda ukuzivumelanisa. Ukuze Ukuyivavanya le ngcamango, yaphuhliswa uvavanyo kunye nabameli indlela ekhethekileyo.

Le nkqubo yaba into yokuba inani elincinane olunye uhlobo iintsholongwane ukuba camngcwe kwi ityhubhu kwaye emva akayicingi antibiotics ezininzi zaye zongezwa kuyo. Inxalenye ezincinane asinda, baza bathunyelwa indawo entsha. Ukuthelekiswa iintsholongwane ezahlukeneyo iityhubhu lwabonisa ukuba kwavela ngokuzenzekelayo nokumelana njengoko ukuqhagamshelana kunye olwa nawo, kwabe emva kwazo.

indlela iphinda yayikukuba laphu fleecy kutshintshelwa Cya, ize ke idluliselwe ngaxeshanye zibe ziindawo eziliqela ecocekileyo. amathanga Entsha cultured kwaye ziphathwe i olwa nawo. Ngenxa yoko, iintsholongwane ezahlukeneyo sasinda iityhubhu amalungiselelo iinxalenye ngokulinganayo eliphakathi.