Lub sijhawm twg ntawm meiosis hla dhau tshwm sim?
Lub sijhawm twg ntawm meiosis hla dhau tshwm sim?

Video: Lub sijhawm twg ntawm meiosis hla dhau tshwm sim?

Video: Lub sijhawm twg ntawm meiosis hla dhau tshwm sim?
Video: TOP DAILY NEWS AROUND THE WORLD UPDATE - THAM XOV XWM TSHIAB HNUB NO 03/22/2021 2024, Kaum ib hlis
Anonim

Kev piav qhia: Thaum chromatids "hloov dua," homologous chromosomes pauv cov khoom siv caj ces, ua rau muaj kev sib txuas tshiab ntawm alleles, txawm tias tib cov noob tseem nyob. Hla hla tshwm sim thaum lub sijhawm prophase kuv ntawm meiosis ua ntej tetrads tau ua raws li txoj kab nruab nrab hauv metaphase I.

Ib yam li ntawd, koj tuaj yeem nug, dab tsi yog hla thiab thaum twg nws tshwm sim hauv meiosis?

Hla mus (genetic recombination) yog cov txheej txheem uas homologous chromosomes ua ke nrog ib leeg thiab sib pauv sib txawv ntawm cov khoom siv caj ces los ua cov chromosomes rov ua dua. Nws tshwm sim ntawm prophase 1 thiab metaphase 1 ntawm meiosis.

Tsis tas li ntawd, puas muaj kev hla dhau ntawm meiosis 2? Meiosis yog cov txheej txheem uas homologous chromosomes raug cais los ua gametes. Meiosis II cais cov muam chromatids ntawm ib leeg. Kev hla dhau tshwm sim hauv meiosis I. Thaum hla dhau , ntu yog pauv ntawm nonsister chromatids.

Ua raws li qhov no hauv kev txiav txim siab, nyob rau theem twg ntawm meiosis hla hla qhov chaw Vim li cas hla dhau qhov tseem ceeb?

Hla hla tshwm sim thaum lub sijhawm prophase I. Qhov no yog qhov tseem ceeb vim nws ua rau muaj kev hloov caj ces. Vim li cas nws tseem ceeb uas meiosis tsim gametes uas tsuas muaj ib nrab ntawm tus lej chromosomes ntawm niam txiv cell?

Qhov tshwm sim ntawm kev hla dhau yog dab tsi?

Nyob rau theem ntawm lub cev, hla dhau yog kev sib pauv ntawm cov ntaub ntawv genetic (DNA loj) los ntawm ib homologous chromosome mus rau lwm qhov. Genetically, crossover tshwm sim nyob rau hauv nce genetic variation nyob rau hauv lub chromosomes ntawm cov ntxhais cell uas tshwm sim los ntawm meiosis.

Pom zoo: