mitotic cell cycle

Definition

Target type: biologicalprocess

Progression through the phases of the mitotic cell cycle, the most common eukaryotic cell cycle, which canonically comprises four successive phases called G1, S, G2, and M and includes replication of the genome and the subsequent segregation of chromosomes into daughter cells. In some variant cell cycles nuclear replication or nuclear division may not be followed by cell division, or G1 and G2 phases may be absent. [GOC:mah, ISBN:0815316194, Reactome:69278]

The mitotic cell cycle is a fundamental process in eukaryotic cells that ensures the accurate duplication and distribution of genetic material to daughter cells. This intricate process can be divided into four distinct phases: **Prophase**, **Metaphase**, **Anaphase**, and **Telophase**.

**Prophase** marks the beginning of mitosis, where the replicated chromosomes condense and become visible under a microscope. The nuclear envelope that surrounds the chromosomes begins to break down, and the centrosomes, which are microtubule-organizing centers, migrate to opposite poles of the cell. Spindle fibers, composed of microtubules, start to extend from the centrosomes.

**Metaphase** is characterized by the alignment of the chromosomes at the cell's equator, forming the metaphase plate. Each chromosome is attached to spindle fibers from both poles of the cell via their kinetochores, specialized protein structures located at the centromere of each chromosome.

**Anaphase** marks the separation of sister chromatids, which are identical copies of a chromosome joined together by the centromere. The spindle fibers shorten, pulling the sister chromatids apart towards opposite poles of the cell.

**Telophase** signifies the final stage of mitosis, where the separated chromosomes arrive at the poles of the cell. The nuclear envelope reforms around each set of chromosomes, and the cytoplasm divides, a process called cytokinesis, forming two daughter cells.

Cytokinesis begins during late anaphase or early telophase and involves the constriction of the plasma membrane, facilitated by a contractile ring composed of actin filaments and myosin. In animal cells, the contractile ring forms a cleavage furrow that pinches off the cell, creating two daughter cells. In plant cells, a cell plate forms between the two daughter nuclei, eventually developing into a new cell wall.

The mitotic cell cycle is tightly regulated by a complex network of proteins known as cyclin-dependent kinases (CDKs). CDKs are activated by cyclins, proteins whose levels fluctuate throughout the cell cycle. The interplay between CDKs and cyclins ensures that each phase of the cell cycle occurs in a timely and orderly manner, preventing errors in DNA replication and chromosome segregation.

Errors in mitosis can lead to aneuploidy, a condition characterized by an abnormal number of chromosomes. Aneuploidy is often associated with cancer and other developmental disorders. Therefore, the accurate regulation and execution of the mitotic cell cycle are critical for maintaining genomic stability and the normal functioning of organisms.'
"

Proteins (53)

Compounds (617)