Kev hloov pauv dab tsi hu ua spontaneous? Yog tias peb txhais lub ntsiab lus mus rau hauv cov lus siv tau, ces cov no yog qhov yuam kev uas tshwm sim hauv cov txheej txheem ntawm kev sib cuam tshuam ntawm cov khoom siv caj ces nrog rau sab hauv thiab / lossis ib puag ncig sab nraud. Xws li kev hloov pauv feem ntau yog random. Lawv raug pom nyob rau hauv qhov chaw mos thiab lwm cov hlwb ntawm lub cev.
Exogenous ua rau kev hloov pauv
Kev hloov pauv hloov pauv tuaj yeem tshwm sim nyob rau hauv kev cuam tshuam ntawm cov tshuaj, hluav taws xob, kub lossis qis, huab cua tsis tshua muaj lossis siab.
Txhua xyoo, qhov nruab nrab, ib tus neeg nqus tau li ib feem kaum ntawm cov hluav taws xob ionizing hluav taws xob uas ua rau lub ntuj tawg. Cov naj npawb no suav nrog gamma hluav taws xob los ntawm lub ntiaj teb lub hauv paus, lub hnub ci cua, thiab cov xov tooj cua ntawm cov ntsiab lus pom nyob rau hauv lub thickness ntawm lub ntiaj teb crust thiab yaj nyob rau hauv cov huab cua. Cov koob tshuaj tau txais kuj nyob ntawm seb tus neeg nyob qhov twg. Ib feem peb ntawm tag nrho cov kev hloov pauv hloov pauv tshwm sim vim qhov xwm txheej no.
UV hluav taws xob, tawm tsam kev ntseeg nrov, ua lub luag haujlwm me hauvQhov tshwm sim ntawm DNA tawg, vim nws tsis tuaj yeem nkag mus tob rau hauv tib neeg lub cev. Tab sis daim tawv nqaij feem ntau raug kev txom nyem los ntawm tshav ntuj ntau dhau (melanoma thiab lwm yam qog noj ntshav). Txawm li cas los xij, cov kab mob ib leeg thiab cov kab mob hloov pauv thaum raug tshav ntuj.
kub dhau lossis qis tuaj yeem ua rau muaj kev hloov pauv hauv cov khoom siv caj ces.
Endogenous ua rau kev hloov pauv
Qhov laj thawj tseem ceeb vim li cas kev hloov pauv ntawm tus kheej tuaj yeem tshwm sim nyob rau hauv cov yam ntxwv endogenous. Cov no muaj xws li metabolic by-products, yuam kev nyob rau hauv tus txheej txheem ntawm replication, kho los yog recombination, thiab lwm yam.
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Kev tsis ua tiav hauv kev rov ua dua:
- kev hloov pauv hloov pauv thiab hloov pauv ntawm cov hauv paus nitrogenous;
- qhov tsis raug ntawm nucleotides vim yog qhov tsis raug hauv DNA polymerases;- tshuaj hloov cov nucleotides Piv txwv li, guanine-cytosine rau adenine-guanine.
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Txoj kev ua yuam kev:-kev hloov pauv hauv cov noob lub luag haujlwm rau kev kho tus kheej ntu ntawm DNA saw tom qab lawv tawg los ntawm kev cuam tshuam ntawm lwm yam.
- Teeb meem nrog kev sib koom ua ke:- kev ua tsis tiav hauv cov txheej txheem hla thaum meiosis lossis mitosis ua rau poob thiab ua tiav ntawm cov hauv paus.
Cov no yog yam tseem ceeb uas ua rau muaj kev hloov pauv ntawm tus kheej. Cov laj thawj rau kev ua tsis tiav tuaj yeem dag hauv kev ua kom cov noob hloov pauv, nrog rau kev hloov pauv ntawm cov tshuaj muaj txiaj ntsig zoo rau hauv cov metabolites nquag uas cuam tshuam rau lub cell nucleus. Tsis tas li ntawd, kuj muaj cov yam ntxwv ntawm cov qauv. Cov no suav nrog kev rov ua dua ntawm nucleotide ib ntus ze ntawm qhov chawchain rearrangements, muaj cov DNA ntxiv seem zoo sib xws hauv cov qauv rau cov noob, nrog rau cov khoom txawb ntawm genome.
Pathogenesis ntawm kev hloov pauv
Kev hloov pauv hloov pauv tshwm sim vim muaj kev cuam tshuam ntawm txhua yam saum toj no ua ke los yog sib cais hauv qee lub sijhawm ntawm lub cell lub neej. Muaj qhov tshwm sim zoo li zawv zawg ua txhaum ntawm kev ua khub ntawm tus ntxhais thiab niam txiv DNA strands. Raws li qhov tshwm sim, loops feem ntau yog tsim los ntawm peptides uas tsis tuaj yeem haum rau hauv cov kab ke kom txaus. Tom qab tshem tawm cov DNA ntau dhau los ntawm tus ntxhais strand, lub loops tuaj yeem raug tshem tawm (kev tshem tawm) thiab ua hauv (duplications, insertions). Cov kev hloov pauv uas tau tshwm sim yog kho nyob rau hauv lub voj voog tom ntej ntawm kev faib cell.
Tus nqi thiab tus lej ntawm kev hloov pauv uas tshwm sim nyob ntawm tus qauv thawj DNA. Qee cov kws tshawb fawb ntseeg tias tag nrho DNA cov kab ke yog mutagenic yog tias lawv tsim khoov.
Ntau yam kev hloov pauv hloov pauv ntau zaus
Dab tsi yog qhov tshwm sim feem ntau ntawm kev hloov pauv hloov pauv hauv cov khoom siv caj ces? Piv txwv ntawm cov xwm txheej zoo li no yog qhov poob ntawm nitrogenous bases thiab tshem tawm cov amino acids. Cytosine residues raug txiav txim siab tshwj xeeb rau lawv.
Nws tau raug pov thawj tias niaj hnub no ntau tshaj li ib nrab ntawm cov vertebrates muaj kev hloov ntawm cytosine residues. Tom qab deamination, methylcytosine hloov mus rau thymine. Tom qab luam ntawm ntu no rov ua qhov yuam kev lossis tshem tawm, lossis ob npaug thiabmutates rau hauv ib feem tshiab.
Lwm qhov laj thawj rau kev hloov pauv tsis tu ncua yog ntau tus pseudogenes. Vim li no, tsis sib xws homologous recombinations tuaj yeem tsim thaum meiosis. Qhov no ua rau muaj kev hloov pauv hauv cov noob, hloov pauv thiab ua ob npaug ntawm cov nucleotide ib ntus.
YPolymerase qauv ntawm mutagenesis
Raws li tus qauv no, kev hloov pauv hloov pauv tshwm sim tshwm sim los ntawm kev ua yuam kev hauv cov molecules uas ua ke DNA. Thawj zaug, tus qauv zoo li no tau nthuav tawm los ntawm Bresler. Nws tau hais tias kev hloov pauv tshwm sim vim qhov tseeb tias polymerases hauv qee kis ntxig cov nucleotides tsis ua tiav rau hauv cov kab ke.
Xyoo tom qab, tom qab kev sim thiab kev sim ntev, qhov kev xav no tau pom zoo thiab lees txais hauv ntiaj teb kev tshawb fawb. Qee cov qauv tau txiav txim siab uas tso cai rau cov kws tshawb fawb los tswj thiab coj cov kev hloov pauv los ntawm kev nthuav tawm qee ntu ntawm DNA rau lub teeb ultraviolet. Yog li, piv txwv li, nws tau pom tias adenine feem ntau embedded opposite lub triplet puas.
Tautomeric qauv ntawm mutagenesis
Lwm txoj kev xav piav qhia txog kev hloov pauv ntawm tus kheej thiab cov khoom siv dag zog tau tawm tswv yim los ntawm Watson thiab Crick (cov neeg nrhiav pom ntawm cov qauv ntawm DNA). Lawv tau hais tias mutagenesis yog raws li lub peev xwm ntawm qee cov DNA hauv paus los hloov mus rau hauv cov ntaub ntawv tautomeric uas hloov txoj hauv kev sib txuas.
Tom qab tshaj tawm, qhov kev xav tau tsim kho. Cov ntaub ntawv tshiab ntawm nucleotides tau pom tom qabirradiating lawv nrog ultraviolet lub teeb. Qhov no tau muab sijhawm rau cov kws tshawb fawb tshiab rau kev tshawb fawb. Kev tshawb fawb niaj hnub no tseem tab tom sib cav txog lub luag haujlwm ntawm cov ntaub ntawv tautomeric hauv kev hloov pauv hloov pauv thiab nws cuam tshuam rau tus lej ntawm cov kev hloov pauv.
Lwm tus qauv
Kev hloov pauv hloov pauv tau tuaj yeem ua txhaum cai ntawm kev lees paub ntawm nucleic acids los ntawm DNA polymerases. Poltaev thiab co-sau elucidated lub mechanism uas kom ua raws li lub hauv paus ntsiab lus ntawm complementarity nyob rau hauv lub synthesis ntawm tus ntxhais DNA molecules. Cov qauv no ua rau nws muaj peev xwm kawm txog qhov tsis tu ncua ntawm cov tsos ntawm spontaneous mutagenesis. Cov kws tshawb fawb tau piav qhia lawv qhov kev tshawb pom los ntawm qhov tseeb tias qhov laj thawj tseem ceeb rau kev hloov pauv hauv cov qauv ntawm DNA yog kev sib txuas ntawm cov tsis-canonical khub nucleotides.
Lawv tau hais tias kev hloov pauv hauv paus tshwm sim vim yog deamination ntawm DNA ntu. Qhov no ua rau muaj kev hloov pauv hauv cytosine rau thymine lossis uracil. Vim li no kev hloov pauv, khub ntawm nucleotides tsis sib haum tau tsim. Yog li ntawd, thaum lub sijhawm rov ua dua tom ntej, kev hloov pauv tshwm sim (lub ntsiab lus hloov ntawm nucleotide hauv paus).
Kev faib tawm ntawm kev hloov pauv: tus kheej
Muaj ntau qhov kev faib tawm ntawm kev hloov pauv nyob ntawm seb qhov kev ntsuas twg cuam tshuam rau lawv. Muaj kev faib tawm raws li qhov kev hloov pauv hauv kev ua haujlwm ntawm cov noob:
- hypomorphic (mutated alleles synthesizes tsawg dua cov proteins, tab sis lawv zoo ib yam li cov qub);
- amorphous (cov noob tau poob tag nrho nws txoj haujlwm);
- antimorphic (tus mutated noob kiag li hloov qhov zoo, uas sawv cev);- neomorphic (cov cim tshiab tshwm sim).
Tab sis qhov kev faib tawm ntau dua uas faib txhua qhov kev hloov pauv hauv kev faib ua feem rau qhov sib txawvqauv. Highlight:
1. Genomic mutations. Cov no suav nrog polyploidy, uas yog, tsim cov genome nrog peb zaug lossis ntau dua chromosomes, thiab aneuploidy, tus naj npawb ntawm chromosomes hauv genome tsis yog ntau yam ntawm tus lej haploid.
2. Kev hloov pauv ntawm chromosomal. Tseem ceeb rearrangements ntawm ib tug neeg seem ntawm chromosomes raug soj ntsuam. Muaj qhov poob ntawm cov ntaub ntawv (kev tshem tawm), nws ob npaug (duplication), kev hloov pauv ntawm nucleotide sequences (inversion), nrog rau kev hloov ntawm chromosome seem mus rau lwm qhov chaw (translocation). 3. Gene mutation. Qhov feem ntau mutation. Hauv DNA saw, ntau lub hauv paus random nitrogenous hloov.
Kev tshwm sim ntawm kev hloov pauv
Kev hloov pauv hloov pauv hloov pauv yog ua rau cov qog nqaij hlav, cov kab mob khaws cia, kev ua haujlwm tsis zoo ntawm lub cev thiab cov ntaub so ntswg hauv tib neeg thiab tsiaj txhu. Yog hais tias ib tug mutated cell nyob rau hauv ib tug loj multicellular kab mob, ces nrog ib tug high degree ntawm qhov tshwm sim nws yuav raug rhuav tshem los ntawm kev ua rau apoptosis (programmed cell tuag). Lub cev tswj cov txheej txheem ntawm kev khaws cia cov khoom siv caj ces thiab, nrog kev pab ntawm lub cev tiv thaiv kab mob, tshem tawm tag nrho cov hlwb puas.
Nyob rau hauv ib rooj plaub ntawm ntau pua txhiab tus, T-lymphocytes tsis muaj sijhawm los paub txog cov qauv cuam tshuam, thiab nws ua rau muaj cov hlwb uas tseem muaj cov noob hloov pauv. Lub conglomerate ntawm cov hlwb twb muaj lwm yam dej num, tsim cov tshuaj lom thiab tsis zoo cuam tshuam rau cov xwm txheej ntawm lub cev.
Yog tias qhov kev hloov pauv tsis tau tshwm sim hauv cov neeg somatic, tab sis nyob rau hauv cov kab mob ntawm tes, ces qhov kev hloov pauv yuav raug pom hauv cov xeeb leej xeeb ntxwv. Lawv yogyog tshwm sim los ntawm congenital organ pathologies, deformities, metabolic ntshawv siab thiab cia kab mob.
Spontaneous mutations: meaning
Qee zaum, qhov kev hloov pauv yav dhau los zoo li tsis muaj txiaj ntsig tuaj yeem muaj txiaj ntsig zoo rau kev hloov pauv rau kev ua neej nyob tshiab. Qhov no sawv cev rau kev hloov pauv raws li kev ntsuas ntawm kev xaiv ntuj. Tsiaj txhu, noog thiab kab yog camouflaged raws li lawv thaj chaw nyob los tiv thaiv lawv tus kheej los ntawm predators. Tab sis yog tias lawv qhov chaw nyob hloov pauv, tom qab ntawd nrog kev pab los ntawm kev hloov pauv, xwm sim tiv thaiv cov tsiaj los ntawm kev ploj mus. Raws li cov xwm txheej tshiab, qhov fittest ciaj sia thiab dhau lub peev xwm no mus rau lwm tus.
Kev hloov pauv tuaj yeem tshwm sim hauv thaj chaw tsis muaj zog ntawm cov genome, thiab tom qab ntawd tsis pom qhov hloov pauv hauv cov phenotype. Nws tuaj yeem tshawb pom "kev tawg" tsuas yog nrog kev pab ntawm cov kev tshawb fawb tshwj xeeb. Qhov no yog qhov tsim nyog los kawm txog keeb kwm ntawm cov tsiaj muaj feem xyuam thiab kos lawv daim ntawv qhia caj ces.
Qhov teeb meem ntawm tus kheej ntawm kev hloov pauv
Nyob rau hauv lub 40s ntawm lub xyoo pua xeem, muaj ib txoj kev xav hais tias kev hloov pauv tsuas yog tshwm sim los ntawm kev cuam tshuam ntawm lwm yam thiab pab hloov mus rau lawv. Txhawm rau ntsuas qhov kev xav no, ib qho kev sim tshwj xeeb thiab rov ua dua tshiab.
Cov txheej txheem muaj nyob rau hauv qhov tseeb tias me me ntawm cov kab mob ntawm tib hom tau sown rau ntawm cov hlab ntsha thiab tom qab ob peb inoculations tshuaj tua kab mob ntxiv rau lawv. Qee cov kab mob muaj sia nyob thiab raug xa mus rau qhov nruab nrab tshiab. Kev sib piv ntawm cov kab mob los ntawm cov hlab ntsha sib txawv tau pom tias kev tawm tsam tau tshwm simspontaneously, ob qho tib si ua ntej thiab tom qab kis tau cov tshuaj tua kab mob.
Txoj kev rov ua dua yog tias cov kab mob kis tau mus rau hauv daim ntaub fleecy, thiab tom qab ntawd hloov ib txhij mus rau ntau lub xov xwm huv. Cov cheeb tsam tshiab tau txais kev coj noj coj ua thiab kho nrog tshuaj tua kab mob. Raws li qhov tshwm sim, cov kab mob nyob hauv tib qhov chaw ntawm qhov nruab nrab muaj sia nyob hauv cov raj sib txawv.
