Mutation vs Recombination
Qhov kev hloov pauv uas tshwm sim hauv genomes vim kev hloov pauv thiab rov ua dua yog qhov sib txawv loj ntawm ob txheej txheem no. Mutation thiab recombination yog ob txheej txheem uas hloov genome nyob rau lub sijhawm. Txawm hais tias ob qho tib si cov txheej txheem tsis cuam tshuam, lawv zoo li lub genome tas li. Feem ntau ntawm cov kev hloov no tsis dhau mus rau tiam tom ntej, tab sis qee qhov kev hloov pauv yuav muaj kev cuam tshuam loj rau cov xeeb ntxwv los ntawm kev txiav txim siab txoj hmoo ntawm hom. Cov kev hloov pauv uas tshwm sim rau DNA hauv cov hlwb somatic feem ntau tsis yog cuab yeej cuab tam thaum cov kev hloov pauv uas tshwm sim rau DNA hauv cov cell germline tej zaum yuav tau txais txiaj ntsig. Tsis tas li ntawd, yog tias qhov kev hloov pauv no ua rau puas tsuaj, ces tej zaum yuav muaj teeb meem loj rau lub cell, kab mob, kab mob lossis txawm rau cov hom. Yog tias nws yog qhov kev hloov pauv, ces nws yuav kawg rau cov hom.
Kev hloov pauv yog dab tsi?
Kev hloov pauv yog txhais raws li kev hloov pauv me me hauv cov kab ke nucleotide ntawm genome thiab cov kev hloov pauv tsis raug kho los ntawm kev kho cov enzymes. Cov kev hloov pauv no tuaj yeem yog ib qho kev hloov pauv (kev hloov pauv), qhov ntsuas me me lossis tshem tawm. Kev hloov pauv ua tus neeg sawv cev hu ua mutagens. Feem ntau cov mutagens yog yuam kev replication, tshuaj thiab hluav taws xob. Cov tshuaj thiab hluav taws xob hloov pauv cov qauv ntawm nucleotide thiab, yog tias qhov hloov pauv tsis kho, ces qhov kev hloov pauv yuav mus tas li.
Muaj ntau lub enzymes uas kho cov kev hloov pauv ntawm DNA, xws li methyl guanine, methyl transferase, thiab DNA polymerase III. Cov enzymes no yuav kuaj xyuas qhov ua yuam kev thiab kev puas tsuaj ua ntej pib ntawm kev faib cell (pre-replicative) thiab tom qab kev faib ntawm tes (post-replicative).
Kev hloov pauv hauv cheeb tsam coding (piv txwv li cov cheeb tsam ntawm DNA qhov twg cov protein txhais lus ib ntus khaws cia) tuaj yeem tsim kev puas tsuaj rau lub cell, lub cev, lossis cov kab mob (xws li kev hloov pauv hauv lub hauv paus thib peb ntawm codon feem ntau tsis ua rau muaj kev phom sij. ua phem – silent mutation).
Piv txwv li: – sickle cell anemia yog ib yam kab mob tshwm sim los ntawm kev hloov pauv.
Mutations hauv noncoding DNA tsis tshua muaj peev xwm ua rau muaj kev phom sij txawm tias, yog tias nws tau xeeb los, nws tuaj yeem tsim kev puas tsuaj yog tias kev hloov pauv ua rau kev ua haujlwm ntawm cov noob uas ntsiag to.
Kev nkag lossis tshem tawm cov kev hloov pauv tau paub tias yuav hloov pauv qhov kev nyeem ntawv (frameshift mutations) ua rau muaj cov protein synthesis tsis zoo ua rau cov kab mob tuag taus hauv tib neeg.
Txawm hais tias feem ntau kev hloov pauv tsis zoo, muaj qee qhov kev hloov pauv uas muaj txiaj ntsig. Piv txwv li, feem ntau ntawm cov neeg nyob sab Europe tiv thaiv kab mob HIV vim muaj qhov hloov pauv tau tshwm sim thaum lub sijhawm hloov pauv.
Kev sib koom ua ke yog dab tsi?
Recombination yog cov txheej txheem ntawm kev hloov pauv loj hauv cov nucleotide ib ntus ntawm genome thiab uas feem ntau tsis kho los ntawm DNA puas kho cov txheej txheem kho. Muaj ob hom recombination, crossover thiab non-crossover recombination. Crossover recombination yog qhov tshwm sim ntawm kev sib pauv DNA tawg ntawm cov chromosomes homologous los ntawm kev tsim ob lub hnub so kev sib tshuam. Non-crossover recombination tshwm sim los ntawm synthesis-dependent strand annealing qhov twg tsis muaj kev sib pauv ntawm cov khoom siv caj ces ntawm chromosomes tshwm sim. Hloov chaw, qhov sib lawv liag ntawm ib chromosome raug theej thiab muab tso rau hauv qhov sib txawv ntawm lwm cov chromosome thiab qhov sib lawv liag ntawm tus qauv chromosome nyob twj ywm.
Recombination yuav tshwm sim nyob rau hauv chromosome, feem ntau, ntawm ob tug muam chromatids (transposition).
Thaum lub sijhawm meiosis hauv cov kab mob germline, recombination yog ib qho kev pom zoo ntawm cov chromosomes uas tsis yog homologous. Hauv cov hlwb somatic, recombination tshwm sim ntawm homologous chromosomes.
Recombination yog qhov tseem ceeb thaum lub sijhawm B cell tsim. Tsis tas li ntawd, muaj qee qhov kev kho mob uas koom nrog kev sib koom ua ke.
Dab tsi yog qhov txawv ntawm Mutation thiab Recombination?
Ob qho kev hloov pauv thiab kev sib txuas ua ke yog cov txheej txheem uas hloov cov nucleotide sib lawv liag ntawm genome. Ob qho txheej txheem ua rau muaj qhov tsis xws luag hauv cov hlwb, lub cev, thiab cov kab mob thiab uas tuaj yeem ua rau tuag taus. Ob qho txheej txheem tuaj yeem muaj txiaj ntsig zoo rau cov kab mob thiab rau hom. Tsis tas li ntawd, ob txheej txheem yog cov txheej txheem tseem ceeb thaum lub sijhawm hloov pauv. Txawm li cas los xij, kuj muaj qee qhov sib txawv ntawm ob txheej txheem. Wb mus saib lawv.
Definition of Recombination and Mutation:
• Kev hloov pauv yog txheej txheem uas hloov cov nucleotide sib lawv liag ntawm cov genome hauv ib qho me me thiab cov kev hloov pauv tsis raug kho los ntawm kev kho cov enzymes.
• Recombination yog cov txheej txheem loj uas hloov cov nucleotide sib lawv liag ntawm cov genome hauv cov nplai loj thiab cov kev hloov pauv feem ntau tsis kho los ntawm DNA puas kho cov txheej txheem kho.
Type:
• Mutation – point mutation and frameshift mutation
• Recombination – crossover recombination thiab non-crossover recombination
Caus:
• Kev hloov pauv - Cov neeg sawv cev ntawm kev hloov pauv suav nrog kev hloov pauv tsis raug, tshuaj lom neeg, thiab hluav taws xob.
• Recombination – Recombination is an enzyme tswj mechanism.
Qhov chaw:
• Kev hloov pauv tuaj yeem tshwm sim ntawm qhov chaw random ntawm genome.
• Recombination feem ntau yog qhov chaw tshwj xeeb.
Kho:
• Kev hloov pauv tuaj yeem kho los ntawm cov txheej txheem kho hauv cell.
• Recombination yog qee zaum kho.
Occurence:
• Kev hloov pauv tuaj yeem tshwm sim txhua lub sijhawm.
• Recombination tshwm sim thaum lub cell division.
Copying noob:
• Mutation tsis luam cov noob.
• Recombination tuaj yeem luam cov noob hauv genome.
