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Mitosis

Cell division allows organisms to grow and develop, as well as reproduce, or in other words, increase the numbers. These are the basis for the survival of the species and the evolution of life. The division of eucaryotic cell consists of two stages. The first is the division of the cell nucleus. The second stage is the division of the cytoplasm and cell organelles contained in it.

Nuclear (eukaryotic) organisms are distinguished by two basic types of cell division. One leads to the production of cells with the same number of chromosomeschromosomeschromosomes and it's called mitosismitosismitosis. The effect of the second, meiosismeiosismeiosis, is the formation of cell with reduced by half haploid number in chromosomes.

During mitosis one mother cell produces two daughter genetically identical cells. One could say that the purpose of this division is to multiply the number of the same cells. In the case of unicellular organisms that have a nucleus, the result of mitosis is an increase in the number of individuals. In the case of multicellular organisms, the result of mitosis is their growth, which consists in increasing the number of cells in the body.

The frequency of mitotic divisions can differ at various periods of the organism's life and in various areas of the body. Usually, it is more intense in the early stages of development and is later slowed. Cells of some tissues divide intensively throughout entire life, e.g. human skin cells, meristem cells in plants.

Both diploid cells and haploid cellshaploid cellhaploid cells may undergo mitosis. As a result of the mitotic division of the diploid celldiploid celldiploid cell two diploid cells will be created, and the haploid cell will become two haploid cells.

Task 3

Discuss the cell division on the basis of the illustration. Specify the number n and 2n for this cell.

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Grafika przedstawia przebieg podziału komórki Od lewej: komórka z pomarańczową i falowaną niebieską linią; strzałka; komórka z dwiema pomarańczowymi i dwiema niebieskimi liniami; strzałka; dwie rozdzielające komórki; dwie strzałki ; dwie rozdzielone komórki w każdym po linii pomarańczowej i niebieskiej falistej

Summary

• Diploid cells contain a double set of chromosomes, and haploid cells contains a single one.

• Prior to cell division, there is always a doubling of the amount of DNA in the cell nucleus.

• Mitosis is the division of the nucleus, thanks to which two daughter cells with identical genetic information are formed from one stem cell.

• Mitosis allows the growth and development of multicellular organisms and the reproduction of unicellular organisms.

Keywords

meiosis, division, haploid cell

Glossary