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What Is The Major Difference Between Meiosis Ii And Mitosis In A Diploid Animal?

Written By Sunday, June 12, 2022 Add Comment Edit

Learning Outcomes

  • Describe the steps of meiosis Two

In some species, cells enter a cursory interphase, orinterkinesis, before entering meiosis II. Interkinesis lacks an S phase, so chromosomes are not duplicated. The two cells produced in meiosis I become through the events of meiosis II in synchrony. During meiosis Ii, the sister chromatids inside the two girl cells split up, forming iv new haploid gametes. The mechanics of meiosis II is similar to mitosis, except that each dividing cell has only i set up of homologous chromosomes. Therefore, each jail cell has half the number of sister chromatids to carve up out equally a diploid prison cell undergoing mitosis.

Prophase 2

If the chromosomes decondensed in telophase I, they condense again. If nuclear envelopes were formed, they fragment into vesicles. The centrosomes that were duplicated during interkinesis move away from each other toward opposite poles, and new spindles are formed.

Prometaphase II

The nuclear envelopes are completely broken downwards, and the spindle is fully formed. Each sister chromatid forms an private kinetochore that attaches to microtubules from opposite poles.

Metaphase Two

The sister chromatids are maximally condensed and aligned at the equator of the jail cell.

Anaphase II

The sister chromatids are pulled apart by the kinetochore microtubules and move toward opposite poles. Non-kinetochore microtubules elongate the cell.

This illustration compares chromosome alignment in meiosis I and meiosis II. In prometaphase I, homologous pairs of chromosomes are held together by chiasmata. In anaphase I, the homologous pair separates and the connections at the chiasmata are broken, but the sister chromatids remain attached at the centromere. In prometaphase II, the sister chromatids are held together at the centromere. In anaphase II, the centromere connections are broken and the sister chromatids separate.

Figure 1. The procedure of chromosome alignment differs betwixt meiosis I and meiosis II. In prometaphase I, microtubules adhere to the fused kinetochores of homologous chromosomes, and the homologous chromosomes are bundled at the midpoint of the cell in metaphase I. In anaphase I, the homologous chromosomes are separated. In prometaphase 2, microtubules attach to the kinetochores of sister chromatids, and the sister chromatids are arranged at the midpoint of the cells in metaphase Two. In anaphase II, the sister chromatids are separated.

Telophase Ii and Cytokinesis

The chromosomes make it at opposite poles and brainstorm to decondense. Nuclear envelopes form effectually the chromosomes. Cytokinesis separates the two cells into four unique haploid cells. At this signal, the newly formed nuclei are both haploid. The cells produced are genetically unique considering of the random assortment of paternal and maternal homologs and because of the recombining of maternal and paternal segments of chromosomes (with their sets of genes) that occurs during crossover. The entire procedure of meiosis is outlined in Figure 2.

This illustration outlines the stages of meiosis. In interphase, before meiosis begins, the chromosomes are duplicated. Meiosis I then proceeds through several stages. In prophase I, the chromosomes begin to condense and the nuclear envelope fragments. Homologous pairs of chromosomes line up, and chiasmata form between them. Crossing over occurs at the chiasmata. Spindle fibers emerge from the centrosomes. In prometaphase I, homologous chromosomes attach to the spindle microtubules. In metaphase I, homologous chromosomes line up at the metaphase plate. In anaphase I, the spindle microtubules pull the homologous pairs of chromosomes apart. In telophase I and cytokinesis, the sister chromatids arrive at the poles of the cell and begin to decondense. The nuclear envelope begins to form again, and cell division occurs. Meiosis II then proceeds through several stages. In prophase II, the sister chromatids condense and the nuclear envelope fragments. A new spindle begins to form. In prometaphase II, the sister chromatids become attached to the kinetochore. In metaphase II, the sister chromatids line up at the metaphase plate. In anaphase II, the sister chromatids are pulled apart by the shortening spindles. In telophase II and cytokinesis, the nuclear envelope forms again and cell division occurs, resulting in four haploid daughter cells.

Effigy 2. An animal prison cell with a diploid number of iv (2northward = four) proceeds through the stages of meiosis to course iv haploid daughter cells.

Review the process of meiosis, observing how chromosomes marshal and migrate, at Meiosis: An Interactive Animation.

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Source: https://courses.lumenlearning.com/wm-biology1/chapter/reading-meiosis-ii/

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