Mitosis
The process of mitosis is best shown in the picture to the left. Although in reality the process is continuous, it is shown here divided into four main stages for convenience. The four stages are called prophase, metaphase, anaphase, and telophase.
Most nuclei contain many chromosomes, but the diagrams shows a cell containing only four chromosomes for convenience. Colors are used to show whether the chromosomes are from the female or male parent. An animal cell is used as an example. The behavior of chromosomes in plant cells is identical. However, plant cells do not contain centrioles and, after nuclear division, a new cell wall must form between the daughter nuclei. It is chromosome behavior, though, that is of particular interest.
Biological Significance of Mitosis
The nuclei of the two daughter cells formed have the same number of chromosomes as the parent nucleus and are genetically idetical. This allows growth of multicellular organisms for unicellular zygotes. Growth may occur over the entire body, as in animals, or be confined to certain regions, as in the growing points of plants.
Replacement of cells and repair of tissues is possible using mitosis followed by cell division. Cells are constantly dying and being replaced by identical cells. In the human body, cell replacement is particularly rapid in the skin and in the lining of the gut. Some animals are able to regenerate whole parts of the body (ex. Starfish).
Mitosis is the basis of asexual reproduction, the production of new individuals of a species by one parent organism. This can take many forms. For a unicellular organism, cell division inevitably results in reproduction. For multicellular organisms, new individuals may be produced which bud off from the parent in various ways.This is particularly common in plants, where it is most commonly a form of vegetative propaga-grows a new plant. This eventually becomes detached from the parent an lives independently. The bud may be part of the stem of an overwintering structure such as a bulb or tuber. The ability to generate whole organisms from single cells, or small groups of cells, is becoming important in biotechnology and genetic modification.
Most nuclei contain many chromosomes, but the diagrams shows a cell containing only four chromosomes for convenience. Colors are used to show whether the chromosomes are from the female or male parent. An animal cell is used as an example. The behavior of chromosomes in plant cells is identical. However, plant cells do not contain centrioles and, after nuclear division, a new cell wall must form between the daughter nuclei. It is chromosome behavior, though, that is of particular interest.
Biological Significance of Mitosis
The nuclei of the two daughter cells formed have the same number of chromosomes as the parent nucleus and are genetically idetical. This allows growth of multicellular organisms for unicellular zygotes. Growth may occur over the entire body, as in animals, or be confined to certain regions, as in the growing points of plants.
Replacement of cells and repair of tissues is possible using mitosis followed by cell division. Cells are constantly dying and being replaced by identical cells. In the human body, cell replacement is particularly rapid in the skin and in the lining of the gut. Some animals are able to regenerate whole parts of the body (ex. Starfish).
Mitosis is the basis of asexual reproduction, the production of new individuals of a species by one parent organism. This can take many forms. For a unicellular organism, cell division inevitably results in reproduction. For multicellular organisms, new individuals may be produced which bud off from the parent in various ways.This is particularly common in plants, where it is most commonly a form of vegetative propaga-grows a new plant. This eventually becomes detached from the parent an lives independently. The bud may be part of the stem of an overwintering structure such as a bulb or tuber. The ability to generate whole organisms from single cells, or small groups of cells, is becoming important in biotechnology and genetic modification.
This image shows mitosis in a plant cell. It also shows asexual reproduction.