Meaning of Cell Cycle
Cells arise from existing cells. Each and every form of life, from single-celled organisms, such as bacteria, to more complex multicellular organisms, such as humans, arise and grow from cell divisions.
The cell cycle is the set of phases, in which a cell goes through to reproduce and generate cells identical to it. The main function of cell division is that a parent cell passes the DNA of the chromosomes to two new cells, generating genetically identical daughters.
However, if each time a cell was rendered it split the rest of its content, it would decrease with each split, until it disappeared (this happens in some exceptions).
So what happens is that all of your internal material, like the organelles, gets duplicated as well.
The cell cycle occurs for our growth, to replace damaged tissue cells, for nail and hair growth, among other functions.
In eukaryotes, this cycle is divided into M phase (accounting for 10% of the division time) and interphase phase (accounting for 90% of the division time).
In interphase, DNA replicates, proteins are synthesized, organelles duplicate, and centrioles divide. We divide this period into three phases:
G1 ( gap , interval and English) – It is the longest phase of the cycle. In it the cell increases in size, synthesizes RNA and proteins. In this phase there are two checkpoints, which look for signs of damaged DNA, or any external signal that there is no division.
S – S represents what is actually happening in the cell right now: DNA synthesis, so that the daughter cells have the same genetic material as the parent cell. Furthermore, the centrosomes also begin to duplicate.
G2 (Gap) – The cell continues to synthesize proteins, duplicating organelles, and there is a rapid increase in size. It is the preparation of the cell for the M phase. The centrosomes move with the help of dynes and kinesins. There is an intense condensation of chromosomes, which marks the end of this phase, until the beginning of the M phase.
In the G2 phase there are also checkpoints for the cell to review the internal and external environment and decide whether cell division will continue.
Some cells have the G0 phase, which is between the M phase and the G1 phase. In it, the cell enters the resting stage of cell division. It occurs, for example, in nerve and muscle cells.
Interphase ends, M phase (mitosis) arrives. This is the stage of cell division itself, in which the genetic material will be divided between two daughter cells. This phase is subdivided into Prophase, Pro-metaphase, Metaphase, Anaphase, and Telophase.
With the end of mitosis comes cytokinesis, which is the end of cell division and is the phase in which the cytoplasms divide in two, generating two daughter cells. This process occurs in different ways between plants and animals.
The duration of the cell cycle varies depending on the type of cell. For example, intestinal epithelial cells have a cell cycle of approximately 12 hours, while fibroblasts in culture medium have approximately 20 hours and liver cells approximately one year.
Cancer stems from problems at these G1 and G2 phase checkpoints. That is, cells continue to divide uncontrollably, even with internal or external signals that division should stop.