Mitosis is a fundamental process of cell division where one cell divides to produce two identical daughter cells. Each daughter cell has the same genetic material as the parent cell. This process is essential for growth, tissue repair, and asexual reproduction in many organisms. During mitosis, the cell's DNA, which is organized into chromosomes, is duplicated and then precisely divided between the two new cells.
Mitosis progresses through several distinct phases. In prophase, chromosomes condense and become visible as the nuclear envelope breaks down. During metaphase, the chromosomes align at the cell's equator, attached to spindle fibers from opposite poles. In anaphase, sister chromatids separate and are pulled toward opposite poles of the cell. Telophase begins when chromosomes reach the poles, with new nuclear envelopes forming around each set of chromosomes. Finally, during cytokinesis, the cytoplasm divides, creating two separate daughter cells.
Before mitosis begins, DNA replication occurs during the S phase of the cell cycle. Each chromosome is duplicated, resulting in two identical sister chromatids joined at a region called the centromere. During prophase, these duplicated chromosomes condense and become visible. In metaphase, they align at the cell's equator. Then, during anaphase, the sister chromatids separate at the centromere and move to opposite poles of the cell. This ensures that each daughter cell receives one complete set of chromosomes, identical to the parent cell's original set.
The cell cycle consists of two main phases: interphase and the M phase. Interphase is further divided into three sub-phases: G1, S, and G2. During G1, the cell grows and carries out normal functions. In the S phase, DNA replication occurs, creating identical copies of each chromosome. G2 is a preparation phase for mitosis, where the cell continues to grow and synthesizes proteins needed for cell division. The M phase includes mitosis, where the nucleus divides, and cytokinesis, where the cytoplasm divides to form two daughter cells. The cell cycle is regulated by checkpoints that ensure each phase is completed correctly before the cell progresses to the next phase.
To summarize what we've learned about mitosis: Mitosis is a type of cell division that produces two genetically identical daughter cells. The process occurs in several distinct phases: prophase, metaphase, anaphase, telophase, and cytokinesis. Before mitosis begins, DNA replication takes place during the S phase of the cell cycle, creating sister chromatids. During anaphase, these sister chromatids separate and move to opposite poles, ensuring each daughter cell receives a complete set of chromosomes. Mitosis is essential for growth, tissue repair, and asexual reproduction in many organisms. This precise process ensures genetic continuity from one cell generation to the next.