Mitosis:
Mitosis is a process of cell duplication and reproduction by which one parent cell divides into two identical daughter cells. This takes place in five different stages (prophase, prometaphase, metaphase, anaphase, and telophase/cytokinesis). (Britannica, n.d)
Prophase: Mitosis starts with prophase, during which chromosomes thicken and coil. The nucleus, which has a rounded structure, shrinks and eventually vanishes.
Prometaphase: During the prometaphase, the physical layer that encloses the nucleus, known as the nuclear envelope, breaks down, releasing the sister chromatids from the nucleus and allowing the nuclear material to be separated into two cells.
Metaphase: In the metaphase, the cell's chromosomes arrange themselves in the center of the cell, similar to a tug of war. Sister chromatids are chromosomes that have been replicated and remain connected at a central place called the centromere.
Anaphase: Each pair of chromosomes is divided into two identical, independent chromosomes through the anaphase. The mitotic spindle is the structure that separates the chromosomes. The spindle then pulls the divided chromosomes to opposite poles of the cell.
Telophase/Cytokinesis: Once the replicated, paired chromosomes have been split and pulled to opposite poles of the cell, telophase begins. To isolate the nuclear DNA from the cytoplasm, a nuclear membrane forms around each set of chromosomes. The chromosomes start to uncoil, making them less compact and dispersed. As well as with telophase, the cell goes through cytokinesis, which separates the mother cell's cytoplasm into two daughter cells. (Nature Education, 2014)
Meiosis is the reduction division of a diploid cell to produce four haploid cells (gametes) that are genetically distinct. (Yourgenome.org, 2014)
Prophase I: Cell has 2n chromosomes (double chromatid) : n is the haploid number of chromosomes.
Metaphase l: Spindle microtubules move homologous pairs to the equator of the cell. Orientation of paternal and maternal chromosomes on either side of the equator is random and independent of other homologous pairs.
Anaphase I: Homologous pairs are separated. One chromosome of each pair moves to each pole.
Telophase l: Chromosomes uncoil. During the interphase that follows, no replication occurs. Reduction of chromosome number from diploid to haploid completed. Cytokinesis occurs.
Prophase Il: Chromosomes, which still consist of two chromatids, condense and become visible.
Metaphase II: the chromosomes are aligned at the center of the cell.
Anaphase Il: Centromeres separate and chromatids are moved to opposite poles.
Telophase II: Chromatids reach opposite poles - Nuclear envelope forms. Cytokinesis occurs.
Meiosis involves a halving of the chromosome number (genetic material), and that’s why is it’s known as a reduction division that allows sexual reproduction to exist in eukaryotes. (BD Editors, 2020)
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