What is mitosis?
- During mitosis one cell divides once to form two identical cells.
- The major purpose of mitosis is for growth and to replace worn out cells.
- If not corrected in time, mistakes made during mitosis can result in changes in the DNA that can potentially lead to genetic disorders.
Mitosis is divided into five phases:
- The DNA in the cell is copied in preparation for cell division, this results in two identical full sets of chromosomes.
- Outside of the nucleus are two centrosomes, each containing a pair of centrioles, these structures are critical for the process of cell division.
- During interphase, microtubules extend from these centrosomes.
- The chromosomes condense into X-shaped structures that can be easily seen under a microscope.
- Each chromosome is composed of two sister chromatids, containing identical genetic information.
- The chromosomes pair up so that both copies of chromosome 1 are together, both copies of chromosome 2 are together, and so on.
- At the end of prophase the membrane around the nucleus in the cell dissolves away releasing the chromosomes.
- The mitotic spindle, consisting of the microtubules and other proteins, extends across the cell between the centrioles as they move to opposite poles of the cell.
- The chromosomes line up neatly end-to-end along the centre (equator) of the cell.
- The centrioles are now at opposite poles of the cell with the mitotic spindle fibres extending from them.
- The mitotic spindle fibres attach to each of the sister chromatids.
- The sister chromatids are then pulled apart by the mitotic spindle which pulls one chromatid to one pole and the other chromatid to the opposite pole.
- At each pole of the cell a full set of chromosomes gather together.
- A membrane forms around each set of chromosomes to create two new nuclei.
- The single cell then pinches in the middle to form two separate daughter cells each containing a full set of chromosomes within a nucleus. This process is known as cytokinesis.
This page was last updated on 2021-07-21
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