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Although we often use the term mitosis to describe the entire process, cell division is not mitosis. Mitosis is the division of the nucleus, the process that ensures that the daughter cells produced have identical sets of chromosomes. Successful cell division depends on three stages: the replication of the DNA and cell organelles in interphase, the division of the nucleus in mitosis and the subsequent division of the cytoplasm and formation of new surface cell membranes and, in plant cells, cellulose cell walls which is described in detail on the next page
Key times and places where mitosis takes place include:
Site of mitosis
Development of an embryo in animals and plants, followed by fetal development in animals. The single cell produced by gamete fusion, divides by mitosis forming entire new organisms.
Germination in plants. The rapid growth of the radical and plumule in a germinating seed depends on rapid mitosis.
Growth in animals and plants. In animals mitosis for growth takes place throughout the organism until the animal is an adult and growth stops. In plants mitosis takes place throughout life in growing regions called the meristems.
Replacements as cells wear out. The cells of the skin and bone marrow are sites of active mitosis replacing skin cells and red blood cells that only have a limited life.
Repair. When an area of tissue is damaged internally or externally, mitosis is used to repair the damage.
The loose structure of DNA in a cell between divisions becomes organised into condensed structures visible under the microscope at the beginning of mitosis