How do cells divide?
Mitosis is a process of cell division that occurs in eukaryotic cells to produce two genetically identical daughter cells. It is a fundamental process for growth, development, and tissue repair in multicellular organisms.
During mitosis, the DNA within the cell nucleus is replicated and then distributed equally between the two daughter cells. The process consists of several distinct phases:
Interphase: This is the phase before mitosis where the cell prepares for division. It includes three stages: G1 (gap 1), S (synthesis), and G2 (gap 2). During interphase, the cell grows, carries out its normal functions, and replicates its DNA in the S phase.
Prophase: The chromatin, which is the DNA and proteins in the nucleus, condenses and forms chromosomes. The nuclear envelope starts to break down, and the mitotic spindle begins to form.
Metaphase: The chromosomes align themselves along the equatorial plane of the cell, known as the metaphase plate. The mitotic spindle, composed of microtubules, attaches to the centromeres of each chromosome.
Anaphase: The centromeres divide, separating the sister chromatids. The microtubules of the mitotic spindle contract, pulling the sister chromatids to opposite poles of the cell.
Telophase: The separated sister chromatids reach the opposite poles of the cell. The nuclear envelope reforms around each set of chromosomes, and the chromosomes begin to decondense. The mitotic spindle disassembles.
Cytokinesis: The final stage of cell division, where the cytoplasm of the cell divides into two daughter cells. In animal cells, a cleavage furrow forms and pinches the cell membrane inward until the cell is divided. In plant cells, a cell plate forms in the middle, which eventually develops into a new cell wall.
After cytokinesis, the two daughter cells enter interphase, and the process can repeat. Each daughter cell receives an identical set of chromosomes and genetic information from the parent cell. This ensures genetic continuity and the growth and repair of tissues and organs in multicellular organisms.
Mitosis is a tightly regulated process, with various checkpoints that monitor the accuracy and integrity of DNA replication and chromosome segregation. Any errors or abnormalities in mitosis can lead to genetic mutations, chromosomal disorders, or cell death.