Phases of mitosis: their characteristics. The significance of mitotic cell division

The cell cycle is the time from one cell division to the next. It passes in two successive stages - the interphase and the actual division. The duration of this process is different and depends on the type of cells.

Interphase is the period between two cellular divisions, the time from the last division to the cell death or loss of the ability to divide.

In this period, the cell grows and doubles its DNA, as well as mitochondria and plastids. In the interphase, protein and other organic compounds are synthesized . The synthesis process is most intensive in the synthetic period of the interphase. At this time, the nuclear chromatids are doubled, energy is accumulated, which will be used during the fission. Also increases the number of cellular organelles and centrioles.

Interphase occupies almost 90% of the cell cycle. After it passes mitosis, which is the main way of dividing the cells of eukaryotes (organisms, the cells of which contain the formed nucleus).

With mitosis, the chromosomes become denser, and a special apparatus is formed, which is responsible for the uniform distribution of hereditary information between the cells that are formed as a result of this process.

Cell division takes place in several stages. The stages of mitosis are characterized by individual characteristics and a certain duration.

Phases of mitosis

In mitotic division of cells, the corresponding phases of mitosis pass: prophase, after it there is a metaphase, anaphase, the final phase is the telophase.

The phases of mitosis are characterized by the following features:

• Prophase - the nuclear envelope disappears. In this phase, the centrioles diverge to the poles of the cell, and the chromosomes condense (thicken);
• Metaphase - is characterized by placement of maximally condensed chromosomes, which consist of two chromatids, on the equator (in the middle) of the cell. This phenomenon is called a metaphase plate. It is in this period that it is possible to examine the chromosomes well under a microscope. In the metaphase of mitosis, there is also the attachment of certain ends of the filaments of the fission spindle to the centromeres of the chromosomes, and the other ends to the centrioles.
• Anaphase - in this period there is a separation of chromosomes into chromatids (they diverge to different poles). In this case, chromatids become separate chromosomes, which consist of only one chromatid thread;
• Telophase - characterized by the decondensation of chromosomes and the formation of a new nuclear envelope around each chromosome. The threads of the spindle of fission disappear, nucleoli appear in the nucleus. In the telophase also passes cytotomy, which is the division of the cytoplasm between daughter cells. This process in animals is carried out by means of a special fission line (a waist that divides the cell in half). In plant cells, the process of cytotomy is provided by a cell plate with the participation of the Golgi complex.

What is the biological significance of the mitosis process?

Phases of mitosis contribute to accurate transmission of hereditary information to daughter cells, regardless of the number of divisions. In this case, each of them receives 1 chromatid, which helps to maintain the constancy of the number of chromosomes in all cells that are formed as a result of division. It is mitosis that ensures the transmission of a stable set of genetic material.