Mitosis (Cell Division via Mitosis)
This page describes the context of mitosis - explaining its position in the series of processes that, together, form the 'cell cycle' for somatic cells (cells relating to the non-reproductive parts of the body) . The four stages of mitosis - prophase, metaphase, anaphase and telophase - are also listed and described. For an illustration of this process see the page - diagram of mitosis.
This follows the page about an introduction to cell division.
Reminder: Mitosis is defined as the type of cell division by which a single cell divides in such a way as to produce two genetically identical 'daughter cells'. This is the method by which the body produces new cells for both growth and repair of aging or damaged tissues throughout the body - as opposed to for sexual reproduction (when meiosis applies).
Mitosis is the simplest of the two ways (mitosis and meiosis) in which the nucleus of cells divide - as part of a process of cell division. The context in which mitosis occurs during the 'cell cycle' is explained as follows:
The Stages of the 'Cell Cycle' for Somatic Cells
In all somatic cells (that is, all cells relating to the non-reproductive parts of the body = all cells except for those of the gametes) the 'cell cycle' consists of two periods:
- Interphase (also
known as interkinesis)
is the period in which the cell is not dividing.
This does not mean that little is happening. Interphases are very active periods during which cells perform all the functions necessary for life, including the synthesis of DNA (deoxyribonucleic acid) so that both of the new cells formed by the miotic phase will contain a complete copy of the original and hence have all the necessary information.
- Miotic phase (M)
- when the cell is dividing.
The miotic phase of the "cell cycle" consists of two stages:
Mitosis is the division of the cell nucleus, and is followed by:
Cytokinesis is the division of the cytoplasm of the cell into two daughter cells.
Mitosis (Nuclear Division)
Interphase is not part of mitosis but is included here
as a reminder that interphase preceeds
Note: Chromatin is a material located in the nucleus of a cells and resembling a thread-like mass. It exists in the form called "chromatin" when the cell is not dividing but forms chromosomes when the cell divides. Chromatin consists of DNA and protein. It can be stained with dyes in order to watch the process of mitosis using a light microscope.
Metaphase is characterized by the "metaphase plate". This is a mid-point region within the cell that is formed/defined by the centromeres of the chromatid pairs aligning along the microtubules at the centre of the miotic spindle.
... then the cytoplasm begins to divide around the two new nuclei:
Cytokinesis (Cytoplasmic Division)
Cytokinesis is the process by which the cytoplasm of the original cell forms the two new ('daughter') cells around the two new ('daughter') nuclei formed by the process of mitosis (or meiosis - cytokinesis being a part of both types of processes of cell division).
In the case of animal - rather than plant - cells, a cleavage furrow forms around the cell's equator then constricts as a ring until it cuts completely through the cell.
When cytokinesis is complete, interphase begins (see further up this page). This begins the next 'cell cycle'.