What is mitosis? Explain the stages of mitosis with the help of a diagram. OR What is meiosis? Explain the significance of meiosis in living organisms.

Mitosis is a type of cell division that results in two daughter cells, each having the same number and kind of chromosomes as the parent cell. It is essential for growth, repair, and asexual reproduction in organisms. Mitosis consists of four main stages: prophase, metaphase, anaphase, and telophase, preceded by interphase (a preparatory phase).

Stages of Mitosis:

1. Interphase (Preparatory Phase)

   • The cell grows and carries out normal metabolic functions.
   • DNA replication occurs during the S phase, ensuring each chromosome consists of two identical sister chromatids.

2. Prophase

   • Chromosomes condense and become visible.
   • The spindle apparatus (composed of microtubules) begins to form.
   • The nuclear envelope breaks down, allowing spindle fibers to interact with chromosomes.

3. Metaphase

   • Chromosomes align at the metaphase plate (equatorial plane) of the cell.
   • Spindle fibers attach to the centromeres of chromosomes via kinetochores.

4. Anaphase

   • Sister chromatids are pulled apart by spindle fibers and move toward opposite poles of the cell.
   • Each chromatid is now considered an individual chromosome.

5. Telophase

   • Chromosomes reach the poles and begin to decondense.
   • A new nuclear envelope forms around each set of chromosomes.
   • The spindle apparatus disassembles.

6. Cytokinesis

   • The cytoplasm divides, forming two separate daughter cells.
   • In animal cells, a cleavage furrow forms; in plant cells, a cell plate develops.

Mitosis ensures genetic stability by producing genetically identical daughter cells, crucial for development, tissue repair, and asexual reproduction.