Mitosis
Role of mitosis
The overall role of mitosis is to produce 2 daughter cells, which are genetically identical to each other and to the parent cell. This is important for:
Growth: Genetically identical cells have the same cell structure and can fulfill the same function as the parent cell.
Repair of tissues: Damaged cells can be replaced by genetically identical cells that can carry out the same function.
Cell replacement: Some cells have a limited life span, such as erythrocytes, and must be regularly replaced with new cells of the same type.
Asexual reproduction: Some eukaryotic organisms can reproduce using mitosis to give genetically identical offspring (clones).
Phases of mitosis
Phase of mitosis | Description |
Prophase | Chromosomes condense and become visible as two chromatids joined at centromere. Centrioles move to opposites poles and form a spindle of microtubules. The nuclear envelope disintegrates and the chromosomes move towards the equator. |
Metaphase | Chromosomes line up at the equator of the cell. Some microtubules span the cell while others attach to the centromeres of the chromosomes via the kinetochore. |
Anaphase | Centromeres split, separating the chromatids. Daughter chromosomes are pulled, centromere first, towards opposite poles of the cell by the shortening spindle fibres. |
Telophase | Chromosomes uncoil and become indistinct as the nuclear envelope reforms. Cytokinesis may start. |
Chromosomes must condense at the beginning of mitosis to produce discrete chromosomes that can be easily moved around the cell by the mitotic spindle to ensure each daughter cell receives the correct number of chromosomes. They do not condense sooner, as when compacted their normal activities e.g. transcription, cannot take place.
Mitosis in animals and plants
Mitosis in animals | Mitosis in plants | |
Tissues where mitosis occurs | Most tissues. | Only occurs in meristem tissue located in the tips of roots and shoots and the cambium. |
Shape of cell | Cell becomes rounded. | Cell does not change shape due to cell wall. |
Spindles | Disappear before cytokinesis. | Partly remain during cytokinesis. |
Microfilaments | Constrict cell to form cleavage furrow | Do not play a major role |
In animal cells, cytokinesis occurs via a cleavage furrow, while in plant cells cytokinesis occurs via a cell plate.
Role of mitosis
The overall role of mitosis is to produce 2 daughter cells, which are genetically identical to each other and to the parent cell. This is important for:
Growth: Genetically identical cells have the same cell structure and can fulfill the same function as the parent cell.
Repair of tissues: Damaged cells can be replaced by genetically identical cells that can carry out the same function.
Cell replacement: Some cells have a limited life span, such as erythrocytes, and must be regularly replaced with new cells of the same type.
Asexual reproduction: Some eukaryotic organisms can reproduce using mitosis to give genetically identical offspring (clones).
Phases of mitosis
Phase of mitosis | Description |
Prophase | Chromosomes condense and become visible as two chromatids joined at centromere. Centrioles move to opposites poles and form a spindle of microtubules. The nuclear envelope disintegrates and the chromosomes move towards the equator. |
Metaphase | Chromosomes line up at the equator of the cell. Some microtubules span the cell while others attach to the centromeres of the chromosomes via the kinetochore. |
Anaphase | Centromeres split, separating the chromatids. Daughter chromosomes are pulled, centromere first, towards opposite poles of the cell by the shortening spindle fibres. |
Telophase | Chromosomes uncoil and become indistinct as the nuclear envelope reforms. Cytokinesis may start. |
Chromosomes must condense at the beginning of mitosis to produce discrete chromosomes that can be easily moved around the cell by the mitotic spindle to ensure each daughter cell receives the correct number of chromosomes. They do not condense sooner, as when compacted their normal activities e.g. transcription, cannot take place.
Mitosis in animals and plants
Mitosis in animals | Mitosis in plants | |
Tissues where mitosis occurs | Most tissues. | Only occurs in meristem tissue located in the tips of roots and shoots and the cambium. |
Shape of cell | Cell becomes rounded. | Cell does not change shape due to cell wall. |
Spindles | Disappear before cytokinesis. | Partly remain during cytokinesis. |
Microfilaments | Constrict cell to form cleavage furrow | Do not play a major role |
In animal cells, cytokinesis occurs via a cleavage furrow, while in plant cells cytokinesis occurs via a cell plate.
