During the reproductive functions of living organisms cell division occurs.Mitosis - is the most common method of reproducing eukaryotic cells through their indirect division.Its biological role is even distribution of chromosomes between successive daughter nuclei that ensures the formation of an identical genetic type of cells and ensures the safety of heredity in the line of subsequent generations of cells.
What is mitosis?It is fundamental to the process of individual development of the organism and its successive transformations with respect to the morphological, physiological and biochemical, that, in the aggregate, of ontogeny.Due to the increased number of mitotic division of cell populations of plant origin.The division of the fertilized egg and the progress of the bulk tissues of animal origin is on the same principle.
Stage mitotic division
duration of mitosis in tissues of animal origin lasts up to 60 minutes in the plant tissue - up to 3 hours. Mitosis and phase,
1. Prophase - the stage of mitotic division, describing a spiral of two similar chromosomes chromatids followed by the formation of the unitmitosis.
2. prometaphase - the period of the rapid collapse of the shell of the nucleus into smaller parts that are identical to the endoplasmic reticulum.
3. Metaphase - long phase of mitotic cell division, consisting of two periods: metakineza - concentration of chromosomes in the mitotic spindle in the form of the equatorial plate - chromosome and chromatid separation.
4. Anaphase - is a fast fission phase, during which the chromatids are separated and distributed to opposite poles.There is only a few minutes.
5. Telophase - the final stage of mitosis, during which stops the movement of chromosomes destroyed myotic apparatus are formed subsidiaries nucleoli, nuclear membrane is formed and there is a division of the cell body into two independent units.
types mitosis
What mitosis and what is its classification?More precisely, it is possible to establish a method to determine its type.Given the unique specificity of mitosis, which manifests itself in different groups of division, certain types of systematization applicable to one taxa are not comparable with others.One of the main features that are used in the formation of a typology, are characteristic of the nuclear membrane, about the behavior of which the three types of mitosis:
1. Closed mitosis is characterized by the formation of the spindle and the subsequent division occurs within the kernel without breaking its shell.
2. Open mitosis is determined by the disintegration of the nuclear envelope during cell division.
3. Semi-closed mitosis.What is mitosis of this type can be identified by the disintegration of the shell only at the poles of mitotic spindles, followed by the formation of "windows polarity."
Another defining feature is the view of the type of mitotic spindle symmetry.Regarding this characteristic of the fundamental concepts of biology share:
- plevromitoza (when spindle symmetrically or asymmetrically divided into two parts);
- ortomitoza (when detected bipolar symmetry of the spindle, and is formed at metaphase equatorial plate).
value mitosis
During mitosis occurs identical reproduction of cells.It is an essential tool for the preservation of the chromosome set.The main role of mitosis matter of copying genetic information.This process affects the growth and development, movement of cells, regeneration and asexual reproduction.
