Txawj hloov: kev faib tawm, ua, piv txwv

Yuav ua li cas yog hu ua txawj hloov? Yog hais tias cov hloov mus rau lub sij hawm nyob rau hauv muaj cov lus, nws yog ib yam uas tsis tshwm sim thaum lub sij hawm sib tham ntawm kev tshuaj ntsuam genetic ntaub ntawv los ntawm sab hauv thiab / los yog lwm cov ib puag ncig. Tej change mas feem ntau yog lo lus. Lawv muaj cai nyob rau hauv pw ua niam txiv, thiab nyob rau hauv lwm cov hlwb ntawm lub cev.

Exogenous ua change

Txawj change yuav tshwm sim nyob rau hauv tus ntawm cov tshuaj, radiation, nyob rau hauv qhov kev txiav txim siab los yog cov uas tsis muaj kub, nyias huab cua los yog kub siab.

Txhua txhua xyoo, cov nruab nrab tus neeg kov txog ib feem kaum txaus siab rau ionizing tawg uas muab lub ntuj tom qab tawg. Qhov no muaj pes tsawg tus muaj xws li gamma tawg los ntawm lub ntiaj teb cov tub ntxhais, hnub ci cua, tej ntsiab, dag nyob rau hauv lub thickness ntawm cov kaub puab thiab yaj nyob rau hauv cov cua. Cov uas ua koob kuj nyob ntawm qhov chaw nws yog neeg. Ib tug peb lub hlis twg ntawm tag nrho cov txawj hloov tshwm sim yog tus txhaum ntawm no tau.

Ultraviolet hluav taws xob, tsis tooj mus rau nrov lub tswv yim, ua ib tug me luag hauj lwm nyob rau hauv yuav ua DNA puas tsuaj, raws li nws muaj peev xwm tsis txeem heev txaus mus rau hauv tib neeg lub cev. Tab sis daim tawv nqaij feem ntau suffers los ntawm ntau insolation (melanoma thiab lwm yam qog nqaij hlav). Txawm li cas los, ib leeg-celled kab mob thiab cov kab mob mutate thaum raug tshav ntuj.

Siab dhau heev lawm los yog muaj tsawg tsawg heev kub yuav ua rau kev hloov nyob rau hauv lub caj khoom.

Endogenous ua change

Lub ntsiab yog vim li cas vim li uas tus txawj hloov yuav tshwm sim, yog endogenous yam. Cov no muaj xws sab-cov khoom ntawm metabolism, uas tsis thaum lub sij hawm replication, kho thiab recombination, thiab lwm tus neeg.

1. Failures nyob rau hauv replication:
   - txawj zaus thiab inversions nitrogenous bases;
   - Improper zoo ntawm nucleotides ntawm DNA polymerases uas tsis;
   - tshuaj muab los ntawm nucleotides, xws li guanine-cytosine rau adenine-guanine.
2. reconstruction kev ua yuam kev:
   - change nyob rau hauv lub noob lub luag hauj lwm rau kho ntawm ib tug neeg seem ntawm cov DNA strand tom qab lawv so nyob rau hauv tus ntawm lwm yam.
3. Teeb meem nrog tus recombination:
   - failures crossover txheej txheem thaum lub sij hawm meiosis thiab mitosis tshwm sim nyob rau hauv los nag thiab extension ntawm lub bases.

Cov no yog cov ntsiab yam tseem ceeb ua rau txawj hloov mus. Cov ua tsis ua hauj lwm yuav ua tau kom qhib mutator noob raws li zoo raws li lub hloov dua siab tshiab ntawm ib tug muaj kev ruaj ntseg tshuaj tebchaw rau hauv ntau yam metabolites uas cuam tshuam rau cell nucleus. Nyob rau hauv tas li ntawd, tseem muaj cov yam ntxwv yam. Cov no muaj xws repetitive nucleotide sequences nyob ze ntawm lub qhov chaw kho Circuit Court, lub xub ntiag ntawm ntxiv DNA cheeb tsam uas yog zoo xws li cov nyob rau hauv cov qauv mus rau lub genome, raws li zoo raws li rooj noj ntsiab ntawm lub genome.

pathogenesis change

Txawj hloov tshwm sim raws li ib tug tshwm sim ntawm tej yam ntawm tag nrho cov yam tseem ceeb uas cuam tshuam rau, ua ke los yog nyias nyob rau hauv ib tug tej lub sij hawm ntawm lub neej ntawm lub cell. Muaj xws li ib tug tshwm sim raws li ib tug mus ua txhaum subsidiary pos thiab niam DNA strands. Raws li ib tug tshwm sim, feem ntau tsim nyob rau ntawm peptide loops, uas yog tsis tau txaus integrate mus rau hauv ib theem zuj zus. Tom qab tshem ruaj feem ntawm cov DNA saw subsidiary loops tau ob resected (deletion) thiab kev (duplications, insertions). Hatched hloov yog tsau nyob rau hauv cov nram no mus ntawm cell division.

Cov kev ceev thiab tus xov tooj ntawm change yog nyob rau ntawm thawj qauv ntawm DNA. Tej zaum ntseeg hais tias nws yog kiag li tag nrho cov DNA sequences ntawm mutagenic yog hais tias lawv tsim khoov rau ob sab.

Feem ntau txawj change

Yuav ua li cas yog feem ntau manifested nyob rau hauv lub caj khoom siv ntawm txawj change? Piv txwv li tej yam kev mob - ib tug tsis nitrogenous bases thiab Hmong amino acids. Tshwj xeeb yog nkag siab lawv pom tau hais tias cytosine residues.

Nws yog muaj pov thawj hais tias niaj hnub no ntau tshaj ib nrab ntawm vertebrates muaj ib tug hloov ntawm cytosine residues. Tom qab deamination methylcytosine yog hloov mus rau thymine. Ua raws li-up ntawm seem no repeats ib qho yuam kev los yog deletes nws los yog doubles thiab mutates mus rau qhov tshiab fragment.

Lwm ua ntawm heev txawj change yog suav tias yog ib tug loj tus naj npawb ntawm pseudogenes. Vim li no, nyob rau hauv tus txheej txheem ntawm meiosis peev xwm yuav tsim tsis zoo tib homologous recombination. Qhov no los tau nyob rau hauv kev hloov nyob rau hauv lub noob ntawm ib tug neeg lem thiab doubling nucleotide sequences.

Polymerase qauv mutagenesis

Raws li cov qauv no, tshwm sim change yog lub txiaj ntsim ntawm random uas tsis molecules, synthesizing DNA. Rau cov thawj lub sij hawm cov qauv no tau raug hais los ntawm Bresler. Nws pom tias change tshwm sim vim lub fact tias nyob rau hauv tej rooj plaub, lub polymerase yog tso rau hauv ib theem zuj zus ntawm nucleotides nekomplimentarnye.

Ntau xyoo tom qab, tom qab lengthy kev ntsuam xyuas thiab thwmsim, no saib tau pom zoo thiab txais nyob rau hauv lub scientific ntiaj teb no. Muaj tau txawm tshem tawm tej yam kev cai uas tso cai rau zaum los tswj thiab ncaj change los ntawm Raug tus kab mob rau ultraviolet txog DNA feem. Yog li ntawd, piv txwv li, pom tias nyob rau hauv pem hauv ntej ntawm lub puas triplet feem ntau ua adenine.

Tautomeric qauv mutagenesis

Lwm lub hom phiaj piav txawj thiab dag hloov tau npaj los ntawm Watson thiab Crick (discoverers ntawm cov DNA qauv). Lawv pom tias lub mutagenesis raws li nyob rau hauv lub peev xwm ntawm ib co DNA los luj hloov dua siab tshiab rau lub tautomeric ntaub ntawv, hloov cov kev twb kev txuas txoj kev bases.

Ua raws li cov ntawv ntawm lub hypothesis tau tau nquag tsim. tshiab cov ntaub ntawv ntawm nucleotides tau kuaj tom qab irradiation nrog ultraviolet lub teeb. Qhov no muab zaum kev tshawb fawb tshiab possibilities. Niaj hnub nimno science yog tseem tham txog lub luag hauj lwm ntawm lub tautomeric ntaub ntawv nyob rau hauv txawj mutagenesis thiab nws cov feem nyob rau hauv tus naj npawb ntawm kuaj change.

lwm yam qauv

Txawj hloov yuav ua tau nyob rau hauv yuam cai ntawm lub Vocabulary ntawm DNA polymerase nucleic acids. Poltaevym li al twb clarified mechanism uas yuam complementarity hauv paus ntsiab lus nyob rau hauv lub synthesis ntawm DNA molecules subsidiaries. Cov qauv no tso cai rau peb kom peb kawm txog cov qauv ntawm occurrences ntawm txawj mutagenesis. Cov soj ntsuam ntawm piav lawv foundations hais tias lub ntsiab yog vim li cas rau kev hloov cov qauv ntawm cov DNA synthesis yog ib tug uas tsis yog-canonical puag officers.

Lawv pom tias yog vim li cas lub ntxub tshwm sim vim deamination ntawm DNA. Qhov no ua rau ib tug kev hloov ntawm cytosine rau thymine los yog uracil. Vim hais tias ntawm cov change yog tsim ib tug khub ntawm incompatible nucleotides. Yog li ntawd, thaum lub sij hawm tom ntej no replication tshwm sim zaus (dot hloov nucleobases).

Ib suam ntawm change: txawj

Muaj ntau classifications ntawm change nyob ntawm seb tus qauv tshau cov lus dag nyob rau ntawm lawv cov tub ntxhais. Muaj yog ib tug faib ntawm cov ua cim hloov noob nuj nqi:

- hypomorphic (mutated alleles ua ke tsawg protein, tab sis lawv zoo sib xws mus rau tus thawj);
- amorphous (noob ua poob lawm nws txoj kev ua);
- antimorfnye (mutated noob reverses cov kos npe rau ntawm uas yog);
- neomorfnye (muaj cov tshiab nta).

Tiam sis qhov ntau ntau faib uas faib tag nrho change nyob rau hauv kev faib ua feem rau cov kuj sib txawv qauv. distinguished:

1. genomic change. Cov no muaj xws polyploidy, piv txwv li lub tsim ntawm lub genome nrog ib tug triple thiab ib co ntawm cov chromosomes, thiab aneuploidy - cov chromosomes nyob rau hauv lub genome tsis yog ib tug ntau ntawm cov haploid.
2. chromosomal hloov. Muaj teeb meem loj restructuring ntawm daim chromosomes. Paub qhov txawv tsis ntawm cov ntaub ntawv (deletion), nws doubling (Individuals), qhov kev hloov nyob rau hauv orientation ntawm lub nucleotide sequences (inversion), raws li zoo raws li hloov mus rau lwm qhov chaw hauv chromosomes lwm qhov chaw (translocation).
3. Caj hloov. Cov feem ntau change. Cov DNA saw yog hloov ob peb random nitrogenous bases.

Lub txim ntawm change

Txawj change - ua qog cia cov kab mob, ua hauj lwm hauv nruab nrog cev thiab cov nqaij mos ntawm cov tib neeg thiab tej tsiaj txhu. Yog hais tias lub mutated cell yog nyob rau hauv ib tug loj multicellular kab mob, qhov ntau dua nws yuav raug rhuav tshem los ntawm lub community launch txog kev puas ntsoog (programmed cell tuag). Lub cev ntawm lwm yam uas tus txheej txheem ntawm kev txuag ntawm kev tshuaj ntsuam genetic cov khoom, thiab nrog rau kev pab los ntawm lub cev tau tshem ntawm tag nrho cov tau puas hlwb.

Nyob rau hauv ib cov ntaub ntawv ntawm pua pua txhiab tus T-lymphocytes tsis muaj lub sij hawm los txheeb xyuas tus cov qauv, thiab nws muab lub clone hlwb uas tseem muaj lub mutated noob. cell conglomerate twb lwm zog, nws ua tej yam tshuaj lom thiab adversely cuam tshuam cov kev mob ntawm lub cev.

Yog hais tias tsis muaj kev hloov tshwm sim nyob rau hauv lub Somatic thiab kab cell, cov kev hloov yuav tsum muaj cai nyob rau hauv lub offspring. Lawv qhia congenital txawv txav hauv nruab nrog cev, deformities, metabolic mob, thiab cia cov kab mob.

Txawj change: tus nqi

Nyob rau hauv tej rooj plaub, yav tas los mag puas change tej zaum yuav pab tau kom hloov mus rau qhov tshiab tej yam kev mob ntawm lub neej. Qhov no yog ib tug hloov raws li ib qho kev ntsuas ntawm natural xaiv. Tsiaj txhu, nas noog thiab kab muaj camouflage coloration coj mus rau lub cheeb tsam ntawm qhov chaw nyob los tiv thaiv lawv tus kheej los ntawm npua. Tab sis, yog hais tias hloov lawv tej vaj tse, ces siv hloov xwm ncav mus tiv thaiv hom kab los ntawm extinction. Nyob rau hauv lub tshiab tej yam kev mob lub fittest ciaj sia thiab kis no muaj peev xwm rau lwm tus neeg.

Cov kev hloov yuav tshwm sim nyob rau hauv uas tsis yog-active qhov chaw ntawm lub genome, thiab ces pom cov kev hloov lub phenotype cai. Nrhiav cov "breakage" yog tau tsuas yog los ntawm txoj kev ntawm tej kev tshawb fawb. Nws yog tsim nyog los kawm txog cov keeb kwm ntawm lwm yam kev hom ntawm cov tsiaj thiab kev npaj ntawm lawv cov caj maps.

Qhov teeb meem ntawm tshwm sim change

Nyob rau hauv lub forties ntawm lub xyoo pua xeem muaj ib tug kev tshawb xav tias cov kev hloov tshwm sim los thiaj tau tuaj los ntawm lwm yam tseem ceeb thiab yuav pab tau lawv hloov. Yuav kom ntsuam xyuas qhov no txoj kev xav, ib tug tshwj xeeb kev kuaj thiab reps txoj kev twb tsim.

Cov txheej txheem yog qhov tseeb hais tias ib tug me me muaj pes tsawg tus ntawm ib hom ntawm cov kab mob yog plated rau lub raj thiab tom qab grafting ob peb tshuaj tua kab mob tau ntxiv rau nws. Ib feem ntawm kab mob ciaj, thiab lawv tau kis mus rau lub tshiab ib puag ncig. Kev sib piv ntawm txawv cov kab mob hlab qhia hais tias kuj sawv nthawv li hu rau nrog ib tug tshuaj tua kab mob, thiab tom qab nws.

repetition txoj kev yog hais tias cov fleecy ntaub pauv mus rau lub kab mob, thiab ces kis ib txhij mus rau hauv ob peb huv tej kev kawm. Tshiab zos twb kuaj thiab kho nrog ib tug tshuaj tua kab mob. Raws li ib tug tshwm sim, ntau yam kab mob ciaj hlab txheej txheem ntawm sib npaug zos feem ntawm qhov nruab nrab.