Here's a breakdown of the stages within each phase and their functions:
Interphase
* G1 Phase (First Gap): The cell grows, synthesizes proteins, and organelles, and prepares for DNA replication. This is a crucial checkpoint to ensure the cell has adequate resources and is ready for DNA replication.
* S Phase (Synthesis): DNA replication occurs, creating two identical copies of the cell's genome. This is the stage where the amount of DNA in the cell doubles.
* G2 Phase (Second Gap): The cell continues to grow, synthesizes proteins, and prepares for mitosis. Another checkpoint ensures that DNA replication was successful and the cell is ready to divide.
M Phase (Mitosis)
* Mitosis: The process of nuclear division where the duplicated chromosomes are separated into two identical daughter nuclei. This process is further divided into four sub-stages:
* Prophase: The chromosomes condense and become visible, the nuclear envelope breaks down, and the spindle fibers begin to form.
* Metaphase: The chromosomes align at the center of the cell (metaphase plate) along the spindle fibers.
* Anaphase: The sister chromatids of each chromosome are pulled apart by the spindle fibers towards opposite poles of the cell.
* Telophase: The chromosomes reach the poles, the nuclear envelope reforms around each set of chromosomes, and the chromosomes begin to uncoil.
Cytokinesis
* Cytokinesis: This is not technically part of mitosis but occurs after it. The cytoplasm divides, creating two separate daughter cells, each with a complete set of chromosomes and organelles.
Summary:
The cell cycle ensures the proper duplication and division of cells, allowing for growth and repair of tissues in multicellular organisms. The four main stages, G1, S, G2, and M, each contribute to the successful completion of this process.
