M Phase of the Cell Cycle

The M phase, or cell division phase, includes mitosis (division of the nucleus) and cytokinesis (division of the cytoplasm). Mitosis consists of four distinct phases: prophase, metaphase, anaphase, and telophase.

Prophase is the longest stage where chromatin condenses into visible chromosomes. Each chromosome comprises two sister chromatids joined at a centromere. The nucleolus disappears, and spindle fibers begin to form from centrioles moving to opposite poles of the cell. The nuclear membrane also dissolves.

During metaphase, the centrioles reach the cell's poles, and spindle fibers align the chromosomes along the cell's equator, ensuring one sister chromatid faces each pole.

In anaphase, spindle fibers shorten, separating the sister chromatids at their centromeres. Once separated, each chromatid is considered a distinct chromosome, moving towards opposite poles of the cell.

Telophase is the final mitotic stage. New nuclear membranes form around each set of chromosomes at the poles. Chromosomes decondense back into chromatin, and the nucleolus reappears. Mitosis is now complete.

Cytokinesis follows mitosis, involving the division of the cytoplasm. In animal cells, the cell membrane pinches inward to form two daughter cells. In plant cells, a cell plate forms along the equator and develops into new cell walls, separating the daughter cells. The M phase concludes, resulting in two genetically identical daughter cells.

The M phase is the final stage of the cell cycle, encompassing mitosis (nuclear division) and cytokinesis (cytoplasmic division). Mitosis progresses through prophase, metaphase, anaphase, and telophase, ultimately yielding two identical daughter cells, both genetically identical to the original cell.