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Meiosis. Before meiosis can happen, the DNA Must replicate, this is done in the stage of interphase. Following interphase the first stage of meiosis occur

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Introduction

Meiosis essay Meiosis is a reduction division which occurs in sexually reproducing organisms to produce gametes. It involves one division of the chromosomes followed by two divisions of the nucleus and cell. The diploid parent cell gives rise to four haploid daughter cells. Before meiosis can happen, the DNA Must replicate, this is done in the stage of interphase. Following interphase the first stage of meiosis occur, this is the reduction division and starts with prophase I. In early prophase I centrioles are at their respective poles and their spindle fibres start to grow. The chromosomes become more visible with a beaded appearance due to the centromeres. The chromosomes become more visible by coiling up and condensing. ...read more.

Middle

The bivalents arrange themselves on the equator in a random assortment. This random assortment leads to genetic variation. The spindle fibres now attach to the centromeres. Anaphase I follows after metaphase. In anaphase I the chromosomes, as pairs of chromatids, are pulled to the opposite poles of the cell. Spindle fibres which are attached to the centromeres contract to pull the chromosomes to their poles. Telophase I now occurs. Cells divide by constriction which is also known as cytokinesis. The nucleolus reforms and the nuclear envelop also reforms. Now each cell has 23 chromosomes. The second stage of Mitosis starts with prophase II. In prophase II the spindle fibres form at right angles to previous. ...read more.

Conclusion

The chromatids now become known as chromosomes. Each of the four cells has a haploid number of chromosomes. There are many similarities between homologous chromosomes. Homologous chromosomes contain the same genes and these genes are in the same position on the chromosomes. These genes code for the same characteristics so the chromosomes code for the same characteristics. When the homologous chromosomes are looked at under a microscope they look the same also they are the same size and length. The centromeres are also in the same position on the homologous chromosomes. Even thought there are many similarities between homologous chromosomes there is also many differences between them. Each of the chromosomes has come from a different parent. A Paternal and a maternal parent. The chromosomes would have different sequence of bases and nucleotides. They may also have different alleles on the homologous chromosomes. ...read more.

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