Cell Cycle and Cell Division - Mitosis and its significance

Mitosis is termed as equational division because the number of chromosomes in the parent and daughter cells remains the same ($2n \rightarrow 2n$).

The cell cycle consists of Interphase ($G_1$, $S$, and $G_2$ phases) and the M Phase (Mitosis). DNA replication occurs specifically during the $S$ phase, where DNA content increases from $2C$ to $4C$, though the chromosome number remains $2n$.

Prophase: Marked by the condensation of chromosomal material. Centrosomes move to opposite poles, and the nuclear envelope, nucleolus, Golgi apparatus, and $ER$ disappear.

Metaphase: Spindle fibers attach to the kinetochores of chromosomes. Chromosomes align at the equator of the cell, forming the metaphase plate.

Anaphase: The centromere of each chromosome splits simultaneously, and sister chromatids (now referred to as daughter chromosomes) migrate toward opposite poles.

Telophase: Chromosomes reach their respective poles and decondense. The nuclear envelope reforms around the chromosome clusters, and the nucleolus and other organelles reappear.

Cytokinesis: The division of cytoplasm. In animal cells, it occurs by the formation of a furrow in the plasma membrane. In plant cells, it occurs by the formation of a cell plate, starting from the center and growing outwards.

Significance of Mitosis: It leads to the production of diploid daughter cells with identical genetic complements, aids in the growth of multicellular organisms, and is crucial for cell repair and replacement (e.g., in the lining of the gut and blood cells).