Mitosis and DNA Molecule

Replication is the copying of the genetic information from one DNA molecule into another DNA molecule. Mitosis and meiosis are similar in the fact that they make new cells. Mitosis replaces and repairs body cells, while meiosis makes gametes like eggs and sperm. Mitosis has an asexual reproduction, while meiosis has a sexual reproduction. These two reproductions have differences in its number of divisions, phases, chromosome numbers, etc.

One difference between mitosis and meiosis would be their production of daughter cells.

Mitosis only goes through one phase of cell division and is a form of asexual reproduction. At the end of its cell division, there are 2 newly formed cells called daughter cells which are identical to its original cell. These 2 sets of chromosomes produce a diploid. Meiosis however goes through 2 cell divisions and is a form of sexual reproduction. In the end of its 2 phases, meiosis produces 4 daughter cells unidentical to its original cell. These 4 new cells are referred to as haploids. Given the end result of the cell divisions, mitosis and meiosis must go through phases before the forming of these new daughter cells.

Prophase, metaphase, anaphase, and telophase are the stages that mitosis and meiosis go through to make new cells. Before mitosis goes through these stages, it must proceed through interphase. Cells usually tend to spend most of their time in interphase in preparation for mitosis. After the cell is prepped, it begins the first stage of mitosis which is prophase. In prophase, the chromosomes become visible, and can be seen as a pair of sister chromatids. The two pairs of centrioles move to the opposite sides of the cell, and the nuclear envelope disappears ending prophase. In metaphase, the chromosomes line up in the middle of the cell. In anaphase, the chromatids are separated and pulled to opposite sides of the cell. In telophase, the chromosomes on the opposite ends of the cells begins to form nuclei to create new cells. At this moment, cytokinesis occurs splitting the cytoplasm separating the newly formed cells. Meiosis goes through some of the same transitions, but there are slight differences from mitosis.

Firstly, meiosis goes through two cell divisions. Like mitosis, before prophase 1, DNA replication occurs similarly in meiosis. Beginning with prophase 1, the chromosomes in the cell condense as well, but they also match up with homologous pairs. These pairs cross over and share information. In Metaphase 1, the homologous pairs line up in the center of the cell. In Anaphase 1, the homologous chromosomes separate, and pulled to opposite ends of the cell. In telophase 1, the daughter cells prepare and ready themselves for meiosis 2. Cytokinesis splits the two new cells, and they’re unidentical to the original cell because of the crossing over in prophase 1. In prophase 2, the nuclear envelope disappears and the chromosomes in both cells condense. In metaphase 2, the chromosomes form a single line down the center of the cell. In anaphase 2, the chromatids pull away and migrate to opposite ends of the cell. In telophase 2, the chromosomes on opposite ends form new nuclei, and cytokinesis splits the cytoplasm again forming 4 nonidentical cells. These haploid cells are known as gametes. An example of gametes are egg cells and sperm cells. When the egg and sperm join each other, a fertilized egg, known as a zygote, is created. Both mitosis and meiosis, although perform different jobs, they both operate to make new cells throughout the body.

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