Division is an important property of cells. Without this process, it is impossible to imagine an increase in the number of various microorganisms or unicellular creatures. In addition, it provides restoration of tissues and even entire organs of multicellular organisms.
It is worth noting that the totality of processes that occur between two divisions is called the
cell cycle. It takes place in stages. So, interphase and the mitotic cycle proper, in which the cell divides, are characteristic.
In order to maintain the appropriate amount of genetic material, DNA molecules are doubling . In addition, protein biosynthesis takes place in the interphase, as well as the formation of important cell structures.
I must say that the interphase is longer than the division itself. It consists of the following steps:
• Presynthetic period - characterized by active growth processes, the synthesis of proteins and nucleic acids, as well as the formation of specific activators of the synthetic period. The cell reaches its normal size and restores the necessary organelles for functioning. The duration of this period is several hours or days.
• Synthetic period - characterized by
DNA replication and histone synthesis, which are responsible for the nucleosome packaging of newly synthesized nucleic acids, as well as for the doubling of chromosomes and centrioles. The duration of this period is up to 12 hours.
• The postsynthetic period - lasting until mitosis, is characterized by the accumulation of energy and the synthesis of tubulin protein , which is necessary for cell division. This period ends in 2-4 hours.
After interphase, the mitosis stage takes place, which is also characterized by certain sequential processes, during which daughter cells with a clearly defined set of chromosomes are formed.
It is worth noting that until today, the reasons for the termination of the division process remain unknown. The mechanism that provokes its renewal is also unknown, although hormones have been established by which the mitotic cycle is activated. Factors that control the size of the cell population are also not fully understood.
Glucocorticoids influence the mitotic cycle of cells. Prolactin, thyrotropin, estrogens and androgens are also able to influence cell division in target tissues in a certain way.
It is worth noting the following feature of benign tumors - their cells are characterized by a circadian mitotic cycle (daily). It is believed that with tumor progression, a decrease in the body's sensitivity to the so-called. kaylonam - inhibitor cells.
The division and size of the cell population is also influenced by the activity of the lysosomal apparatus, since its enzymes are capable of exhibiting a destructive effect.
I must say that the process of formation of new cells depends on the type of tissue, the influence of external factors and the physiological state of the body, therefore, in some cases it may have certain individual characteristics, characterized by further growth of the cell population or the cessation of this process.