Cattle have 60 chromosomes in somatic cells. Determine the number of chromosomes and DNA molecules in the ovary cells during ovogenesis at the interphase before the division and after the division of meiosis I. Explain the results obtained at each stage.
1) in the interphase before the start of division, the number of DNA molecules is 120; the number of chromosomes – 60;
2) after meiosis I, the number of chromosomes is 30; the number of DNA molecules – 60;
3) before the start of division in the interphase, DNA molecules double, their number increases, and the number of chromosomes does not change – 60, each chromosome consists of two sister chromatids;
4) meiosis I – reduction division, so the number of chromosomes and the number of DNA molecules is reduced by 2 times
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