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Meiosis and genetic diversity

Let's look at how the direction of arrangement and intersection change the combination of the four gametes.

    B11 · Meiosis and genetic diversityReady
    Let's look at how the direction of arrangement and intersection change the combination of the four gametes. You can also experiment with the numbers and controls below.

    Life sciences, genetics, gene expression / principles and exploration

    Meiosis and genetic diversity — principles and investigation

    Meiosis is the process of creating genetically diverse gametes by halving the number of chromosomes. Change the arrangement of homologous chromosomes and crossovers between non-sister chromatids. Distinguishing what separates in meiosis I and meiosis II allows us to explain the two pathways through which diversity arises.

    How does it work?

    In meiosis I, homologous chromosomes are separated, and in meiosis II, sister chromatids are separated. Independence, separation and intersection create diversity.

    Key relationship

    1 DNA replication, 2 divisions → Gametes n=2, DNA=1

    Try this investigation

    1. Proceed with division using the step button or execution. The two pairs of colors represent parental origins. The centromere is the upper point, and the A/a and B/b labels are at 55% of the length. The marker combination changes only when the intersection position is before the marker.
    2. Turn off the intersection and record both alignment directions. If we combine the two records, we get 2²=4 types.
    3. Fix the arrangement and compare the intersections before and after the A/a cover. In crossovers behind the marker, the terminal color is exchanged, but the allele on the marker remains the same.

    Interpreting your results

    What is one gamete based on 2n=4 and G1 DNA=2?

    DNA is copied once and then divided twice. In meiosis I, homologous chromosomes are separated, and in meiosis II, sister chromatids are separated. gamete n=2, DNA=1.

    Assumptions and limitations

    The number of chromosomes is based on the centromere and the relative amount of G1 DNA = 2, which is the same as in the mitosis experiment. The table is based on one daughter cell from the end of meiosis Ⅰ. The stage without nuclear membrane does not define a value per nucleus. Crossover occurs only once between two non-sister chromatids of a selected pair. Location, color, and time are for explanatory purposes only and do not cover genetic map distances or segmentation errors.