Question

What is mitosis?Definition,stages​

Answer 1

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Answer 2

Mitosis is a fundamental process in cell biology that allows a eukaryotic cell to divide and create two genetically identical daughter cells. It is crucial for growth, tissue repair, and the maintenance of a multicellular organism's body.

Mitosis consists of several distinct stages, which can be summarized as follows:

1. Interphase: This is the phase before mitosis itself begins, where the cell prepares for division. Interphase is divided into three sub-stages: a. G1 (Gap 1): During this phase, the cell grows and carries out its normal functions. b. S (Synthesis): In this stage, DNA replication occurs. The cell makes an identical copy of its DNA, ensuring that each daughter cell will have a complete set of genetic information. c. G2 (Gap 2): The cell continues to grow and prepares for mitosis. It checks for any errors in DNA replication and completes any necessary repairs.

2. Prophase: The first official stage of mitosis. During prophase, several key events take place:

   • Chromatin condenses into visible chromosomes.
   • The nuclear envelope breaks down, allowing the spindle fibers to access the chromosomes.
   • Spindle fibers, which are microtubules, begin to form and extend from opposite poles of the cell.

3. Metaphase: In this stage, the chromosomes align along the cell's equator, known as the metaphase plate. The spindle fibers attach to the centromeres of each chromosome, ensuring they are held in place.

4. Anaphase: During anaphase, the sister chromatids (the identical copies of each chromosome) are pulled apart towards opposite poles of the cell. This separation ensures that each daughter cell will receive an identical set of chromosomes.

5. Telophase: Telophase marks the near-end of mitosis. During this stage:

   • The separated chromatids reach opposite poles of the cell.
   • New nuclear envelopes begin to form around each set of chromatids, resulting in the formation of two distinct nuclei.
   • The spindle fibers start to break down and disappear.

6. Cytokinesis: Although not technically a part of mitosis, cytokinesis is the final step in cell division. It involves the physical splitting of the cell into two separate daughter cells. In animal cells, a contractile ring composed of actin filaments pinches the cell membrane, creating two separate cells. In plant cells, a structure called the cell plate forms, which eventually becomes the cell wall that divides the cell.

Once cytokinesis is complete, you have two genetically identical daughter cells, each with the same number of chromosomes as the original parent cell. These cells can then enter interphase and continue their normal functions or go through additional rounds of the cell cycle as needed for growth and repair.