During interphase the DNA is not condensed and is being replicated. By prophase the chromosomes form, long with kinetochores. During metaphase the chromosomes align along the middle of the cell. The kinetochores start to pull and the sister chromatids divide into daughter chromosomes during anaphase. In telophase the nuclear envelope reform. Finally, the cell divides in cytokinesis.

Meiosis reduces and rearranges the chromosomes of a diploid cell. In prophase I of meiosis I, the chromosomes are rearranged from how the tetrads are formed. The two homologous chromosomes come together and form a tetrad, and where the two chromosomes cross, a crossing over occurs where parts of the chromosomes swap between the two. The tetrads are rearranged during metaphase I on how they line up down the middle of the cell. Hence, meiosis has rearranged the chromosomes. In anaphase I the tetrads are pulled apart, unlike in mitosis where the chromosomes are pulled apart, this difference reduces the number of chromosomes in each daughter cell by half, making the two cells haploid. In interphase II, the DNA is not replicated keeping the cells haploid. The two cells divide again, and four haploid cells are produced.
Down Syndrome is a chromosomal abnormality caused by an extra twenty-first chromosome. Down Syndrome affects the phenotypes of the person by creating a distinct facial appearance, intellectual disability, short stature, and or speech delay. Down Syndrome could result from a defect in meiosis while separating. During prophase I of meiosis, while crossing over of the homologous chromosomes, one of the chromosomes would not separate making two twenty-first chromosomes in a haploid cell, resulting in a Down Syndrome offspring.
Many species reproduce by parthenogenesis or cloning, bypassing the meiotic process. In cloning, the DNA is replicated and the organism divides. The DNA of the parent organism and the DNA of the offspring will be identical. This is because the parent organism copies the DNA and through mitosis, creates an offspring, so there is no genetic difference.