Cellular division

Cell division . A very important part of the cell cycle in which an initial cell (called the “mother”) divides to form daughter cells. Thanks to cell division, the growth of multicellular organisms occurs with the growth of tissues (biology) and vegetative reproduction in unicellular beings .

Summary

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  • 1 Process description
  • 2 Types of reproduction associated with cell division
  • 3 Cell division processes
  • 4 Factors that explain cell division
  • 5 See also
  • 6 Fountains

Process description

The total growth of biological systems is described in terms of the cell growth division cycle. Living systems are composed of cells capable of synthesizing new molecules similar to existing ones. Thus, cells grow en masse, even though their individual growth capacity is limited. Although there are exceptions, a cell only doubles its mass before stopping its growth. The division renews the growth capacity, since the daughter cells begin to grow immediately after the division. These normally do not divide, but rather grow back. Division enables growth, and growth enables division; thus, biological systems increase by stages of duplication and division.

Gene conservation, in this cycle, depends on the duplication of the genetic material before division, followed by its exact qualitative and quantitative distribution in the daughter cells.

The distribution is carried out by mitosis in all plant and animal cells, as well as in protozoa, fungi and other microorganisms . The multiplication of the cell always includes the multiplication of the nucleus. On the other hand, in some cases cells grow without division. In them, nuclear divisions parallel growth, but without division of the cell body.

Types of reproduction associated with cell division

Bipartition : the division of the mother cell into two daughter cells, each new cell is a new individual with structures and functions identical to the mother cell. This type of reproduction is presented by organisms such as Bacteria , Amebas and Algae .

Budding : occurs when new individuals are produced from buds. The budding process is frequent in Sponges , Coelenterates , Bryozoans . In one or several areas of the parent organism, an invagination or bud is produced that develops and at a given moment suffers a constriction at the base and separates from the parent, beginning its life as a new being. The daughter buds can present other buds that are called secondary buds.

In some organisms, colonies can form when the buds do not separate from the parent organism. In the most evolved forms of Bryozoa , it is observed in the budding process that it is carried out in a more complicated way.

The number of individuals in a colony, how they are grouped, and their degree of differentiation varies and is often characteristic of a given species. Bryozoans can originate new individuals on extensions called stolons and the process is called Stolonization .

Certain species of animals can have internal budding, buds that survive in unfavorable conditions thanks to a protective envelope. In the case of freshwater sponges , the buds have a protective capsule and there is a reserve substance inside. When spring arrives, the protective capsule is lost and the new sponge emerges from the bud. In freshwater Bryozoans, a layer of Chitin and Calcium is produced and they do not need a reserve substance because they are in a state of hibernation .

Sporulation : sputation or sporogenesis consists of a process of cellular differentiation to reach the production of dispersive reproductive cells of resistance called Spores . This process occurs in Fungi , Amoebas , Lichens , some types of Bacteria , Protozoa , Sporozoa (such as the Plasmodium that causes Malaria ), and is frequent in Plants (especially Algae , Mosses and Ferns ).), groups of very different evolutionary origins, but with similar reproductive strategies, all of them can resort to the formation of resistance cells to favor dispersion.

During sporulation, the nucleus divides into several fragments, and by asymmetric cell division, a part of the cytoplasm surrounds each new nucleus, giving rise to spores. Depending on each species, a parciable number of spores can be produced and an independent individual will develop from each one of them.

cell division processes

  • Binary fissionis the form of cell division in prokaryotic cells .
  • Mitosisis the most common form of cell division in eukaryotic cells . A cell that has acquired certain parameters or conditions of size, volume, energy storage, environmental factors, can fully replicate its DNA endowment and divide into two daughter cells, usually the same. Both cells will be Diploid or Haploid , depending on the parent cell.
  • Meiosisis the division of a diploid cell into four haploid cells. This cell division occurs in multicellular organisms to produce haploid gametes , which may later fuse to form a diploid cell called a zygote at fertilization .

Multicellular beings replace their cellular complement thanks to cell division and it is usually associated with cell differentiation . In some animals, cell division stops at some point and the cells eventually age. Senescent cells deteriorate and die, due to the aging of the body. Cells stop dividing because Telomeres get shorter with each division and cannot protect Chromosomes . Cancer cells are immortal . An enzyme called Telomerase allows these cells to divide indefinitely.

The main characteristic of cell division in eukaryotic organisms is the conservation of the genetic mechanisms of cell cycle control and cell division, since it has remained practically unchanged from organisms as simple as yeast to creatures as complex as humans. throughout biological evolution.

Factors that explain cell division

One theory states that there is a time when the cell begins to grow very large, which causes the area/volume ratio to decrease. When the area of ​​the plasmatic membrane of the cell is much smaller in relation to its total volume, there are difficulties in the Reabsorption and Transport of Nutrients , thus making it necessary for cell division to occur.

 

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