Question

Draw the process of meiosis I, including each step. In this drawing denote what happens with the chromosomes and what structures form and what chromosomes are separated. Denote the two specific phases of meiosis where crossing-over and assortment occurs. Describe in detail what occurs in both of these events, including the structures created, and how they provide genetic variation in sexual reprodiction. Also denote where Mendel's law of segregation and law of independent assortment occur.

Answer 1

Centriole Spindle fiber formation NUcleolus Ucleus ** Crossing over of homologous chromosomes. Chromatin fibers Interphase Prophase of meiosis Big Synapsis of homologous chromosomes occurring before crossing over in the nucleus

lire Homologous chromosomes Arranged on the equator Separating homologous chromosomes. Metaphase Anaphase

Nucleus formation Telophasel and cytokinesis Haploid daughter cells after Meiosis

Meiosis produces 2 haploid daughter cells. During the process, the homologous chromosmes pair up , the phenomenon called synapsis. After pairing of the homologous chromosmes crossing over occurs. Crossing over the process where chromatid bits of the homologous chromosmesbreak and the broken bits get exchanged between the two homologous chromosmes. This exchange of chromatid bits brings variation in the population. Variation in t he population is important in bringing evolution in the population.

During metaphase all the paired homologous chromosmes are arranged on the equator. The homologous chromosomes separate during anaphase and go to the opposite poles. This happens because of the shortening of the spindle fibers which help the chromosomes to be carried to poles. So, each opposite pole where the daughter nuclei form, there are non-homologous chromosomes present. This is how the chromosomes separate or segregate to make haploid nuclei and cells after meiosis I.

When the homologous chromosomes are segregating or separating, any chromosome can go to any of the two poles. The pateranl and maternal chromosmes will assort independently not depending on the movement of each other. Because fo such independent assortment of the chromosomes we see huge variations in the population.

The above processes of segregation and independent assortment agree to the Laws of Mendels segregation and independent assortment.