Mitosis is the type of cell division in which a cell divides into two daughter cells. In this post, you’ll learn about the main Phases of mitosis like prophase, metaphase, anaphase, and telophase. Before learning of stages of mitosis we learn in detail about mitosis and mitosis Examples. Keep reading …
What is Mitosis?
Mitosis is the process by which a nucleus is divided into two identical daughter cells. Mitosis takes place in all parts of plants and animals. The time is taken for mitosis of one nucleus change with the species of organisms and prevailing temperature. Drosophila, the fruit fly, takes 7 minutes while man, 100 minutes.
Main Phases of Mitosis
Mitosis is a continuous process, but four main phases are recognized, each of which merges into the other.
- Chromosomes become visible as two lengthwise halves or chromatids. The chromatids are attached to each other at the centromere. The chromosomes are visible because the chromatin material has shortened and thickened by condensation.
- The centrosome divides to form two centrioles that move towards the opposite pole of the cell and form spindle fibers. Centrioles are absent in higher plants.
- The nuclear membrane disappears.
- Nucleoli (singular nucleolus) disappear.
- From each centriole, fibers originate forming a star-shaped aster. Spindle fibers, centrioles, and aster are collectively called mitotic apparatus.
Chromosomes arrange themselves on the cell equator position or midline of the spindle fibers each chromosome is attached to a separate spindle fiber by its centromere,
- The centromere divides and the two chromatids are drawn apart and become chromosomes.
- The chromosomes move towards the opposite poles drawn by the spindle fibers.
- Chromosomes reform by an uncoiling process, become thinner and finally disappear.
- Nucleoli reform.
- Nuclear membranes reappear. While the nucleus is dividing by mitosis, the cell cytoplasm and plant cell wall are also dividing.
Animal cells and amoebae divide by ‘furrowing’ of the plasma membrane cytoplasm along with the cell equator position. Plant cells develop a cell plate along with the cell equator position which grows inwards to meet the opposite cell plate. Cellulose is then deposited on either side of the cell plate, the original cell now has formed into daughters cells. Read Also: Mitosis Vs Meiosis
What is the Importance of Mitosis?
- Formation new cells
Growth or increase in body size is due to the formation of new cells in tissues. It happens through mitosis.
- Repairing of cells
Repair of damaged and wounded tissues is only due to mitosis.
- Renewal of blood cells
Renewal o blood and epidermal cells in the skin are due to mitosis.
- Asexual & vegetative reproduction
Asexual and vegetative reproduction is essentially division or multiplication by mitosis.
- An identical number of chromosomes
Each daughter cell gets a complete set of chromosomes identical to that of the parent cell. Thus the genetic information remains unchanged generation after generation because there is no crossing over the recombination.