1. Interphase: This is the stage where the cell grows and copies its DNA, preparing for division. It consists of three subphases:
* G1 phase (Gap 1): The cell grows and synthesizes proteins and organelles.
* S phase (Synthesis): The cell replicates its DNA, resulting in two identical copies of each chromosome.
* G2 phase (Gap 2): The cell continues to grow and prepares for mitosis or meiosis.
2. M phase (Mitotic phase): This is the actual division stage where the cell divides its replicated DNA and cytoplasm into two new daughter cells. It consists of two subphases:
* Mitosis: This is the division of the nuclear material (DNA). It involves four stages:
* Prophase: The chromosomes condense, the nuclear envelope breaks down, and the spindle fibers form.
* Metaphase: The chromosomes line up at the center of the cell, attached to the spindle fibers.
* Anaphase: The sister chromatids (the two identical copies of each chromosome) separate and move to opposite poles of the cell.
* Telophase: The chromosomes reach the poles of the cell, the nuclear envelope reforms around them, and the chromosomes uncoil.
* Cytokinesis: This is the division of the cytoplasm. In animal cells, it involves the formation of a cleavage furrow that pinches the cell in two. In plant cells, it involves the formation of a cell plate that grows outward from the center of the cell, eventually separating the two daughter cells.
Types of cell division:
* Mitosis: Produces two identical daughter cells with the same number of chromosomes as the parent cell. This is the primary method of cell division for growth, repair, and asexual reproduction in multicellular organisms.
* Meiosis: Produces four daughter cells with half the number of chromosomes as the parent cell. This is the process of cell division involved in sexual reproduction, where each daughter cell receives a unique combination of genetic material.
Regulation of cell division:
Cell division is tightly regulated by a complex network of proteins and signaling pathways. This ensures that cells divide only when necessary and in a controlled manner. Dysregulation of cell division can lead to various diseases, including cancer.
