Mutations yog ib qho tseem ceeb ntawm kev kawm rau cytogeneticists thiab biochemists. Nws yog kev hloov pauv, noob lossis chromosomal, uas feem ntau yog ua rau cov kab mob sib kis. Nyob rau hauv tej yam ntuj tso, chromosomal rearrangements tshwm sim tsis tshua muaj. Kev hloov pauv tshwm sim los ntawm cov tshuaj lom neeg, cov mutagens lom, lossis cov yam ntxwv ntawm lub cev xws li hluav taws xob ionizing feem ntau yog qhov ua rau muaj qhov tsis zoo hauv lub cev thiab cov kab mob malignancies.
Cov ntaub ntawv dav dav txog kev hloov pauv
Hugh de Vries txhais qhov kev hloov pauv raws li kev hloov pauv tam sim ntawm kev hloov pauv hloov pauv. Qhov tshwm sim no muaj nyob rau hauv genome ntawm tag nrho cov kab mob nyob, los ntawm cov kab mob mus rau tib neeg. Raws li ib txwm muaj, kev hloov pauv hauv nucleic acids tshwm sim tsis tshua muaj, nrog ntau zaus ntawm kwv yees li 1 10–4 – 1 10–10.
Nyob ntawm seb cov khoom siv caj ces cuam tshuam los ntawm kev hloov pauv, kev hloov pauv tau muab faib ua genomic, chromosomal thiab noob. Genomic sawv daws yuav txuam nrog kev hloov pauv ntawm cov chromosomes (monosomy, trisomy, tetrasomy); chromosomal yog txuam nrog kev hloov hauv cov qauv ntawm tus neegchromosomes (deletions, duplications, translocations); Cov noob hloov pauv cuam tshuam rau ib lub noob. Yog tias qhov kev hloov pauv cuam tshuam tsuas yog ib khub nucleotides, ces nws yog qhov hloov pauv.
Zoo ntawm qhov ua rau ua rau lawv, qhov tshwm sim ntawm qhov tshwm sim thiab kev hloov pauv tau txawv.
Kev hloov pauv hloov pauv hloov pauv
Kev hloov pauv hloov pauv tshwm sim hauv lub cev raws li kev cuam tshuam ntawm sab hauv. Kev hloov pauv hloov pauv tau suav tias yog ib txwm, lawv tsis tshua ua rau muaj qhov tshwm sim loj rau lub cev. Feem ntau, cov kev hloov pauv no tshwm sim hauv tib lub noob, cuam tshuam nrog kev hloov pauv ntawm cov hauv paus - purine rau lwm qhov purine (kev hloov pauv), lossis purine rau pyrimidine (transversion).
Qhov tseem ceeb tsawg dua qhov kev hloov pauv tshwm sim tshwm sim hauv chromosomes. Chromosomal spontaneous mutations feem ntau yog sawv cev los ntawm kev hloov pauv (kev hloov pauv ntawm ib lossis ntau cov noob ntawm ib chromosome mus rau lwm qhov) thiab inversions (hloov nyob rau hauv ib theem ntawm cov noob hauv ib chromosome).
Kev hloov pauv tshwm sim hauv cov hlwb ntawm lub cev raws li kev cuam tshuam ntawm cov tshuaj, hluav taws xob lossis cov khoom siv rov ua dua ntawm cov kab mob. Cov kev hloov pauv zoo li no tshwm sim ntau dua li qhov tshwm sim ntawm tus kheej thiab muaj qhov tshwm sim loj dua. Lawv cuam tshuam rau tib neeg cov noob thiab pab pawg ntawm cov noob, thaiv cov synthesis ntawm tus kheej cov proteins. Induced mutations feem ntau thoob ntiaj teb cuam tshuam rau genome, nws yog nyob rau hauv kev cuam tshuam ntawm mutagens uas txawv txav chromosomes tshwm nyob rau hauv lub cell: isochromosomes, nplhaib chromosomes, dicentrics.
Mutagens, ntxiv rau chromosomal rearrangements, ua rau DNA puas: ob-strand so,kev tsim ntawm DNA crosslinks.
Piv txwv ntawm tshuaj mutagens
Tshuaj mutagens suav nrog nitrates, nitrites, nitrogen base analogs, nitrous acid, tshuaj tua kab, hydroxylamine, qee yam khoom noj ntxiv.
Nitrous acid ua rau cov amino pawg tau cleaved los ntawm nitrogenous bases thiab hloov los ntawm lwm pab pawg neeg. Qhov no ua rau cov ntsiab lus hloov pauv. Hydroxylamine kuj ua rau muaj tshuaj lom neeg hloov pauv.
Nitrates thiab nitrites hauv koob tshuaj ntau ua rau muaj mob qog noj ntshav. Qee cov khoom noj muaj txiaj ntsig ua rau muaj kev cuam tshuam arylation ntawm nucleic acids, uas ua rau muaj kev cuam tshuam ntawm kev hloov pauv thiab kev txhais lus.
Tshuaj mutagens muaj ntau haiv neeg. Feem ntau nws yog cov tshuaj uas ua rau muaj kev hloov pauv hauv chromosomes.
Lub cev mutagens
Lub cev mutagens suav nrog hluav taws xob ionizing, feem ntau yog luv luv, thiab ultraviolet. Ultraviolet pib cov txheej txheem ntawm lipid peroxidation nyob rau hauv daim nyias nyias, provokes tsim ntawm ntau yam tsis xws luag nyob rau hauv DNA.
X-ray thiab gamma hluav taws xob ua rau muaj kev hloov pauv ntawm qib chromosomes. Cov hlwb no tsis muaj peev xwm ntawm kev faib tawm, lawv tuag thaum lub sijhawm apoptosis. Induced mutations kuj tuaj yeem cuam tshuam rau tib neeg cov noob. Piv txwv li, thaiv cov qog suppressor noob ua rau cov qog.
Piv txwv ntawm induced rearrangements
Piv txwv ntawm induced mutations yog ntau yam kab mob caj ces, uas feem ntau tshwm sim nyob rau hauv cov cheeb tsam uas muajraug rau lub cev los yog tshuaj mutagenic yam. Nws paub, tshwj xeeb tshaj yog, nyob rau hauv lub xeev Indian ntawm Kerala, qhov twg txhua xyoo koob tshuaj ionizing hluav taws xob zoo tshaj li tus qauv los ntawm 10 lub sij hawm, qhov zaus ntawm yug me nyuam nrog Down syndrome (trisomy ntawm 21st chromosome) yog nce. Nyob rau hauv Suav koog tsev kawm ntawv ntawm Yangjiang, ib tug loj npaum li cas ntawm radioactive monazite tau pom nyob rau hauv cov av. Cov ntsiab lus tsis ruaj khov hauv nws cov muaj pes tsawg leeg (cerium, thorium, uranium) lwj nrog kev tso tawm ntawm gamma quanta. Kev raug hluav taws xob luv luv hauv lub nroog tau ua rau muaj coob tus menyuam yug los nrog kev quaj miv syndrome (tshem tawm ntawm ntu loj ntawm 8th chromosome), nrog rau kev mob qog noj ntshav ntau ntxiv. Lwm qhov piv txwv: thaum Lub Ib Hlis 1987, cov ntaub ntawv sau tseg ntawm cov menyuam yaus uas muaj Down syndrome tau sau npe hauv Ukraine, cuam tshuam nrog Chernobyl kev sib tsoo. Hauv thawj peb lub hlis twg ntawm cev xeeb tub, tus me nyuam hauv plab feem ntau nkag siab txog qhov cuam tshuam ntawm lub cev thiab tshuaj mutagens, yog li kev siv hluav taws xob ntau ntau tau ua rau muaj qhov nce ntawm cov chromosome anomalies.
Ib qho ntawm cov tshuaj mutagens uas muaj npe nrov tshaj plaws hauv keeb kwm yog sedative Thalidomide, tsim nyob rau hauv lub teb chaws Yelemees xyoo 1950. Kev noj cov tshuaj no tau ua rau muaj ntau tus menyuam yug los uas muaj ntau yam kev txawv txav ntawm caj ces.
Txoj kev hloov pauv tau tshwm sim feem ntau yog siv los ntawm cov kws tshawb fawb los nrhiav txoj hauv kev zoo tshaj plaws los tawm tsam cov kab mob autoimmune thiab caj ces txawv txav cuam tshuam nrog cov protein hypersecretion.
