Explain and justify the positioning behaviour of chromosomes throughout mitosis and meiosis.

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Mitosis and meiosis both use prophase, metaphase, anaphase, and telophase for the stages of chromosome movement that happen within them.

Let's start with mitosis. The goal of mitosis is to produce a duplicate cell, so however many chromosomes are present in a normal body cell, that is the number of...

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Mitosis and meiosis both use prophase, metaphase, anaphase, and telophase for the stages of chromosome movement that happen within them.

Let's start with mitosis. The goal of mitosis is to produce a duplicate cell, so however many chromosomes are present in a normal body cell, that is the number of chromosomes that each daughter cell will end up with. I'll use humans in my examples. A normal human body cell has forty-six chromosomes. During interphase of the cell cycle, those chromosomes will be replicated. When prophase begins, the chromosomes become visible, and the nuclear membrane begins to disintegrate. The replicated chromosomes will be attached to the original chromosome at the centromere, and they will be called sister chromatids at this point. The sister chromatids will then line up across the cell's equator during metaphase. The centrioles will have migrated to opposite sides of the cell, and spindle fibers will extend from them and attach to each chromatid. Anaphase will pull the chromatids to opposite sides of the cell, and telophase will begin soon after. The nuclear membrane will begin reforming, and the cell membrane will begin to pinch inward. This will continue until full cell separation has occurred and each new daughter cell has the original forty-six chromosome count.

Meiosis is similar; however, during metaphase 1, chromosomes will line up across the cell's equator alongside their homologous pair. The homologous pair, together with the sister chromatids, is known as a tetrad. Anaphase 1 will separate the homologous pairs from each other. Metaphase 2 will see the sister chromatids lined up across the middle of the cell, much like metaphase from mitosis. Anaphase 2 and telophase 2 will also happen very similarly to mitosis; however, the end result of meiosis is four cells that each contain twenty-three chromosomes. Because the cells contain half of the genetic information, they are the gamete cells used for sexual reproduction.

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