Qhov Tseem Ceeb Qhov txawv - DNA Kev puas tsuaj vs Kev hloov pauv
DNA dais cov ntaub ntawv caj ces ntawm txhua lub cell. Nws yog khaws cia nrog cov ntaub ntawv keeb kwm yav dhau los uas yuav tsum tau dhau los ntawm ib tiam mus rau lwm tiam. Cov ntaub ntawv ntawm caj ces yog muab zais rau hauv DNA molecules nyob rau hauv daim ntawv ntawm cov nucleotide cov sequences. Muaj ntau billions ntawm nucleotides, thiab lawv tau teem rau hauv pawg hu ua noob. Cov noob yog encoded nrog cov lus qhia ua kom tag nrho cov proteins thiab lwm yam khoom tseem ceeb rau lub cev kev loj hlob, kev loj hlob, thiab metabolism. Tus naj npawb thiab qhov tseeb ntawm nucleotides hauv DNA txiav txim siab cov khoom ntawm txhua yam kabmob. Yog li ntawd, kev tswj hwm kev ncaj ncees thiab kev ruaj ntseg ntawm DNA yog qhov tseem ceeb rau lub neej. Txawm li cas los xij, DNA tau raug hloov pauv tas li vim muaj ntau yam xws li sab hauv thiab ib puag ncig. DNA puas thiab kev hloov pauv yog cov kev hloov pauv uas tshwm sim hauv DNA. DNA puas yog hu ua kev tawg lossis kev hloov pauv ntawm lub cev lossis tshuaj lom neeg ntawm DNA. Kev hloov pauv yog txhais raws li kev hloov pauv hauv cov DNA sib lawv liag. Qhov sib txawv tseem ceeb ntawm DNA kev puas tsuaj thiab kev hloov pauv yog qhov kev puas tsuaj DNA tuaj yeem raug kho los ntawm enzymes thaum kev hloov pauv tsis tuaj yeem lees paub thiab kho los ntawm enzymes.
DNA Damage yog dab tsi?
DNA kev puas tsuaj yog qhov txawv txav ntawm lub cev thiab / lossis cov qauv tshuaj ntawm DNA. Vim yog DNA puas, nws cov qauv deviates los ntawm cov qauv ib txwm. DNA puas feem ntau tshwm sim thaum DNA replication. Ntxiv qhov tsis ncaj ncees lawm nucleotide thaum lub sijhawm rov ua dua tshwm sim hauv txhua 10 8 tus khub. Txawm li cas los xij, 99% ntawm qhov yuam kev raug kho thaum lub sijhawm ua pov thawj ntawm DNA polymerase enzymes. Qhov seem 1% yuav tsis kho thiab yuav raug xa mus rau lwm tiam neeg raws li kev hloov pauv.
DNA kev puas tsuaj tuaj yeem tshwm sim los ntawm kev qhia txog cov hauv paus tsis raug cai thaum rov ua dua, deamination lossis lwm yam kev hloov pauv ntawm cov hauv paus, poob ntawm lub hauv paus ntawm DNA caj qaum uas ua rau cov chaw abasic, ib qho strand so, ob chav strand so, tsim pyrimidine dimers, intra thiab interstrand crosslinking, thiab lwm yam. Cov DNA puas tau kho tas li los ntawm ntau lub DNA kho cov txheej txheem hauv cov hlwb. Lawv suav nrog kev kho lub hauv paus kev txiav txim siab, kho nucleotide kev txiav txim siab, kho qhov tsis sib xws, kev sib koom ua ke kawg lossis tsis yog homologous kawg koom, thiab lwm yam.
Muaj ntau yam ua rau DNA puas tsuaj. DNA replication yuam kev ua rau DNA puas. DNA tuaj yeem raug puas tsuaj vim raug UV teeb, tshuaj lom neeg, hluav taws xob ionizing, X-rays, tshuaj tiv thaiv qog thiab cov khoom puas tsuaj ntawm cov cellular by-products (oxygen radicals, alkylating agents).
Daim duab 01: DNA puas los ntawm UV Radiation
Kev hloov pauv yog dab tsi?
Kev hloov pauv yog qhov hloov pauv hauv lub hauv paus ntawm DNA. Enzymes tsis paub txog DNA yuam kev thaum lawv tshwm sim hauv ob qho tib si. Yog hais tias lub hauv paus hloov tshwm sim nyob rau hauv ob strands nyob rau hauv daim ntawv ntawm kev hloov, lawv tsis tuaj yeem kho los ntawm cov enzymes. Yog li ntawd, kev hloov pauv tau xa mus rau qhov sib npaug ntawm cov genomes thiab dhau mus rau tiam neeg ua tiav, tsim cov phenotypes sib txawv. Mutated genes ua rau cov amino acid sib txawv uas tsim cov khoom protein tsis raug.
Kev hloov pauv tuaj yeem tsim tawm vim qhov chaw endogenous lossis exogenous xws li tsis ua haujlwm ntawm kev kho cov txheej txheem, yuam kev ntawm DNA recombination thiab replication, oxidative stress, tshuaj lom, X ray, UV teeb thiab lwm yam. Thaum lub sij hawm replication, kev hloov pauv tshwm sim ntawm tus nqi. ntawm ib qho kev hloov pauv hauv txhua 10 billion lub hauv paus khub uas tau rov ua dua.
Cov txiaj ntsig ntawm kev hloov pauv tuaj yeem yog qhov zoo (muaj txiaj ntsig), tsis zoo (kev puas tsuaj) thiab nruab nrab. Kev hloov pauv muaj ntau yam xws li kev hloov pauv hloov pauv, hloov pauv hloov pauv, hloov pauv tsis pom, hloov pauv ntsiag to thiab tsis muaj qhov hloov pauv.
Daim duab 02: Kev hloov pauv los ntawm UV
DNA Kev puas tsuaj thiab kev hloov pauv yog dab tsi?
DNA Damage vs Mutation |
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| DNA kev puas tsuaj yog ib qho kev hloov pauv xws li kev tawg lossis kev hloov pauv uas qhia txog kev sib txawv ntawm cov qauv ob-helical ib txwm. | Kev hloov pauv yog qhov kev puas tsuaj DNA uas tuaj yeem ua rau muaj kev hloov pauv ntawm genotype. |
| Reparability | |
| DNA kev puas tsuaj tuaj yeem raug kho los ntawm enzymes. | Kev hloov pauv tsis tuaj yeem kho los ntawm enzymes. |
| Vim kev puas tsuaj raug kho los ntawm cov enzymes, lawv tsis dhau mus rau tiam neeg ua tiav | Lawv dhau mus rau tiam neeg vam meej. |
| Nyob rau hauv Replication | |
| DNA kev puas tsuaj feem ntau tshwm sim thaum lub sijhawm rov ua dua tshiab hauv kev sib txuas tshiab. | Kev hloov pauv feem ntau tshwm sim thaum lub sijhawm rov ua dua thaum xaiv cov qauv tsis raug, thiab ob qho tib si raug hloov kho. |
Summary – DNA Damage vs Mutation
DNA kev puas tsuaj thiab kev hloov pauv yog ob hom kev ua yuam kev tshwm sim hauv DNA qauv. DNA puas yog ib qho kev hloov kho nyob rau hauv cov tshuaj los yog lub cev qauv ntawm DNA hloov nws mus rau hauv ib tug hloov DNA molecule tshaj lub qub DNA molecule. Cov kev hloov kho no tau taug qab sai sai los ntawm cov enzymes thiab kho ua ntej hloov mus rau qhov kev hloov pauv qub uas hu ua kev hloov pauv. Kev hloov pauv yog qhov hloov pauv qub txeeg qub teg hauv lub hauv paus ntawm DNA. Lawv tsis nquag lees paub los ntawm cov enzymes thiab raug kho. Kev hloov pauv ua rau cov khoom lag luam tsis xav tau thiab cov phenotypes sib txawv. Qhov no yog qhov txawv ntawm DNA puas thiab kev hloov pauv.
