Process and function of miosis and mitosis
Miosis:
Miosis is the process of cell division that occurs during sexual reproduction, resulting in the production of haploid gametes (sperm and egg cells). This process involves two consecutive divisions referred to as meiosis I and meiosis II. The process of miosis is divided into four stages: Prophase I, Metaphase I, Anaphase I, Telophase I, Prophase II, Metaphase II, Anaphase II, and Telophase II.
1. Prophase I: Chromosomes condense, and homologous chromosomes pair up in a process called synapsis.
2. Metaphase I: Homologous chromosomes line up at the equator of the cell, and the spindle fibers attach to the kinetochores.
3. Anaphase I: Homologous chromosomes separate and move to opposite poles of the cell.
4. Telophase I: Two new nuclei form, and the cell is temporarily split into two cells by cytokinesis.
5. Prophase II: Chromosomes condense again, and the spindle apparatus forms.
6. Metaphase II: Chromosomes line up at the equator of the cell, and the spindle fibers attach to the kinetochores.
7. Anaphase II: Sister chromatids separate and are pulled to opposite poles of the cell.
8. Telophase II: The cell divides into two gametes, each with half the number of chromosomes as the original cell.
Mitosis:
Mitosis is the process of cell division that occurs in somatic cells (non-reproductive cells) for growth, repair and maintenance. It involves the duplication and separation of genetic material into two identical daughter cells. Mitosis is divided into four stages: prophase, metaphase, anaphase and telophase.
1. Prophase: Chromosomes, which were replicated during interphase to have two chromatids, start to condense and become visible under a microscope. The nucleolus and nuclear envelope disappear, and spindle fibers begin to assemble.
2. Metaphase: The chromosomes align at the equator or metaphase plate of the cell. The spindle fibers attach to the chromosomes and are pulled towards opposite poles.
3. Anaphase: Sister chromatids separate as the spindle fibers shorten and pull them towards the poles of the cell.
4. Telophase: Two new nuclear envelopes form around the separated chromatids at the opposite poles of the cell. Chromosomes begin to unwind, and the spindle fibers disassemble.
5. Cytokinesis: The cell membrane pinches in, dividing the cytoplasm and organelles equally between two genetically identical daughter cells.
Thus, both miosis and mitosis are vital processes in cell division and are responsible for the generation of new cells. However, while miosis is related to sexual reproduction, mitosis occurs in somatic cells for growth and repair.