What is cellular cycle?

What Does cellular cycle Mean

It is called cell cycle at all the stages developed between two divisions of cells that are carried out consecutively. The process begins at the moment when a new cell emerges, which descends from another that divided, and ends when that cell carries out the next division and gives rise to another pair, which are considered its daughters.

The cell cycle can be understood as a series of events that occur in an orderly fashion as a cell grows and eventually divides into two daughter cells . Cells go through two states : the interface (non-dividing state) and the M phase (dividing state).

At the interface, the cell performs certain specific functions as it progresses toward cell division. The initial stage is known as the G1 Phase , when it begins to synthesize RNA and proteins . In this phase, the cell manages to double its mass and size. Then comes the S Phase with the synthesis of DNA and the duplication of each chromosome.
The cell cycle continues with the G2 Phase of the interface: RNA and protein synthesis follows and division begins . In this instance the cell enters the second state, called Phase M .
This M Phase is when the cell division takes place: the progenitor cell divides into two other cells (the daughter cells), which are identical. Phase M includes mitosis and cytokinesis .
The mitosis is a biological process that takes place in the nucleus of a eukaryotic cell, just before it is divided; In short, it consists of the characteristic hereditary material being shared equally. The cytokinesis , meanwhile, is the physical division of the cytoplasm into two cells.
Regulation of the cell cycle
In 2001, an explanation for the regulation of the cell cycle was disseminated, which can be observed in eukaryotic organisms from the point of view of the decisions that are made at certain critical moments of the cycle itself, in particular mitosis. From this some questions arise, such as why DNA replicates only once or why it is possible that cellular euploidy is maintained .
The answer can be found in the fact that during the G1 phase, cyclin facilitates that the regulators called Cdc6 can be added to the origin recognition complex ( ORC ), which are in charge of requesting the action of the genetic replication machinery in the middle of a process in which a complex is generated for future DNA replication.

When the beginning of the S phase arrives, Cdk-S generates Cdc6 dissociation and degrades its proteins, in addition to exporting Mcm to the cytosol, so that until the next cycle it is not possible for the origin of replication to recruit a prereplicative complex. Throughout the G2 and M phase, the uniqueness of this structure is maintained until the level of Cdk activity declines after mitosis and it is again possible to add Mdm and Cdc6 for the next cycle.
Another question raised by this study is how to enter mitosis . To answer it, we can think that cyclin B, common in Cdk-M, is present throughout the cycle. Cyclin is usually inhibited by phosphorylation through the protein called Wee ; however, when the G2 phase is nearing completion, a phosphate called Cdc25 is activated and removes the inhibitory phosphate to increase its activity. It also activates Cdk-M and inhibits Wee, thereby causing positive feedback that results in the accumulation of Cdk-M.

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