Chiasmata yog cov qauv tshwj xeeb chromatin uas txuas homologous chromosomes ua ke kom txog thaum anaphase I (Fig. 45.1 thiab 45.10). Lawv tsim ntawm qhov chaw uas programmed DNA tawg tsim los ntawm Spo11 tau dhau los ua txoj hauv kev rov ua dua tshiab los tsim kev sib tw.
Chiasmata tshwm sim nyob qhov twg hauv meiosis?
Lub chiasmata tau pom thaum lub sijhawm the diplotene theem ntawm prophase I ntawm meiosis, tab sis qhov tseeb "hloov-overs" ntawm cov khoom siv caj ces tau xav tias yuav tshwm sim thaum lub sijhawm pachytene dhau los.
txheej txheem dab tsi tshwm sim ntawm chiasmata?
Ntawm chiasmata, homologous chromosomes pauv cov noob, tso cai cov ntaub ntawv caj ces los ntawm leej txiv thiab leej niam chromatids sib pauv, thiab kev sib txuas ntawm niam txiv thiab niam cov noob tuaj yeem dhau mus. mus rau noob neej. Cov txheej txheem no yog qhov tseem ceeb hauv cov kab mob diploid kom ntseeg tau tias muaj kev hloov pauv hauv cov neeg laus.
Puas muaj chiasmata hauv meiosis?
Lub chiasma yog ib qho qauv tsim ntawm ib khub ntawm homologous chromosomes los ntawm crossover recombination thiab lub cev txuas cov homologous chromosomes thaum lub sij hawm meiosis. … Txawm li cas los xij, tag nrho kev ua haujlwm ntawm chiasmata thaum lub sij hawm meiosis tsis to taub tag nrho.
Kev hla dhau feem ntau tshwm sim nyob qhov twg?
Kev piav qhia: Thaum chromatids "hloov dhau," homologous chromosomes pauv cov khoom siv caj ces, ua rau muaj kev sib txuas tshiab ntawm alleles, txawm tiastib cov noob tseem muaj nyob. Kev hla dhau tshwm sim thaum lub sijhawm prophase I ntawm meiosis ua ntej tetrads tau ua raws li txoj kab nruab nrab hauv metaphase I.
