Cell Cycle Meaning

What is Cell Cycle:

The cell cycle is the life cycle or life cycle of a cell. In eukaryotic cells (with a defined nucleus), the cell cycle is divided into interphase and M phase (mitosis or meiosis and cytokinesis).

In most of the time of the cell cycle, the cell is in the interphase, being the preparatory, resting or dormant part. The interface is further divided into 3 stages:

  • The G-phase1 or presynthetic period: where the cell can remain for hours, days or throughout its life,
  • The S phase or period of synthesis: where chromosomes are replicated, and
  • The G-phasetwo: when the duplicate content is prepared for cell division.

On the other hand, the M phase is divided into cytokinesis, where the cytoplasm is divided, and mitosis, which is summarized in the following phases or processes:

  • Prophase: chromosomes condense, the mitotic spindle is created that captures the chromosomes, the nucleolus disappears and the nuclear envelope breaks down.
  • metaphase: the metaphysical plate is generated.
  • Anaphase: sister chromatids are separated.
  • telephase: mitotic spindle disappears and the nucleolus appears.

A cycle is characterized by not being linear. In this sense, each of the daughter cells has the ability to start the process again.

The cell cycle is important as are the life cycles, since they allow the reproduction and regeneration of the cells that make up all the organs, tissues and elements of living organisms.

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Cell cycle phases

Cellular cycle

The cell cycle of eukaryotic cells is divided into two main phases: the interphase and the mitotic phase or M phase.

interface

The interface involves most of the life of the cell. In this phase, the cell lives, grows, and prepares to reproduce. The interphase of the cell cycle is divided into three stages:

  1. G-phase1 or presynthetic: the cell grows, copies the organelles and makes the molecular components that it will need for the later stages.
  2. S phase (synthesis): DNA that is in the form of chromatin is replicated and the centrometer is doubled.
  3. G-phasetwo: the cell grows further, makes more of the necessary organelles and proteins, and rearranges the duplicated contents to prepare for mitosis.

It is important to note that before the cell enters the M phase or mitotic phase, 2 identical and complete copies of the chromosome will be connected, called sister chromatids. Being connected at the centrometer, they are considered 1 chromosome. Then, when separated in anaphase, each one will be considered a different chromosome.

The genetic information of DNA is in the form of chromatin before DNA replication. When chromatin condenses, the DNA in eukaryotic cells is divided into linear pieces called chromosomes. In prokaryotic cells such as bacteria, the chromosomes are usually circular.

Mitotic phase (M)

The mitotic phase is the equal distribution of the genetic material that was duplicated in the interphase. This is important, since cell cycle disorder can lead to disease, and cells with too many or too few chromosomes are often weak or cause cancer.

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The mitotic phase is divided into mitosis or meiosis and cytokinesis.

Mitosis is the process by which a mother cell divides into 2 daughter cells. This cell division is asexual, of diploid (2n) cells, whose chromosomes come in homologous pairs.

Meiosis, on the other hand, is a sexual division of haploid cells, such as sperm and egg cells, which need to be combined to form a complete set of diploid chromosomes.

The mitotic phase is divided into four substages:

Prophase

Prophase is subdivided in some texts into early prophase and late prophase or prometaphase.

In the early prophase, the chromosomes condense and the mitotic spindle is formed, which will organize and move the chromosomes. The nucleolus disappears, being the signal of preparation of the nucleus to decompose.

In the prometaphase, the mitotic spindle captures and organizes the chromosomes. The chromosomes finish their condensation, the nuclear envelope breaks down to release the chromosomes, and the mitotic spindle grows to capture more chromosomes.

metaphase

In metaphase, the mitotic spindle captures all the chromosomes made up of two sister chromatids and aligns them in the center of the cell creating what is called a metaphysical plate.

Before the next stage of mitosis, the mitotic spindle generates a checkpoint by checking that all existing chromosomes are on the metaphysical plate and the protein section of the centromere that joins the sister chromatids (kinetochore) is correctly connected to the microtubules of the mitosis. mitotic spindle. This way they can be divided evenly.

Anaphase

In anaphase, the sister chromatids are separated and pulled toward opposite poles of the spindle while the chromosome-free microtubules that make up the mitotic spindle grow to elongate the cell. This process is driven by motor proteins.

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telephase

In telephase, the mitotic spindle disappears while the nuclear membrane and nucleolus appear.

Meanwhile, the chromosomes decondense to make way for the final step of cytokinesis, a process that overlaps with anaphase or telephase.

The cytokinesis It is the final stage of cell division, in which the cytoplasm is divided to finish forming two daughter cells of a mother cell. This process begins along with anaphase.

See also Cytokinesis.