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Describe the cell cycle, including the name of each phase in interphase and mitosis

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The cell cycle is a series of events that take place in a cell leading to its division and replication. It consists of two main phases: interphase and the mitotic phase (mitosis and cytokinesis). Here’s a detailed description of each phase:

Interphase

Interphase is the longest part of the cell cycle, during which the cell grows and prepares for division. It is subdivided into three distinct phases:

  1. G1 Phase (Gap 1):

    • The cell grows in size and synthesizes mRNA and proteins that are required for DNA synthesis.
    • It also undergoes normal cellular functions and prepares for DNA replication.

  2. S Phase (Synthesis):

    • DNA is replicated, resulting in the duplication of chromosomes.
    • Each chromosome is now composed of two sister chromatids, joined at the centromere.

  3. G2 Phase (Gap 2):

    • The cell continues to grow and produces proteins necessary for mitosis.
    • At this point, the cell also checks for DNA damage and makes repairs if needed, ensuring everything is in order before proceeding to mitosis.

Mitotic Phase

The mitotic phase consists of mitosis and cytokinesis, where the cell divides its copied DNA and cytoplasm to form two new daughter cells.

  1. Prophase:

    • Chromatin condenses into visible chromosomes.
    • The mitotic spindle begins to form from the centrosomes, which move to opposite poles of the cell.
    • The nuclear envelope begins to break down.

  2. Metaphase:

    • Chromosomes line up along the metaphase plate (the cell's equatorial plane).
    • Spindle fibers attach to the centromeres of the chromosomes from opposite poles.

  3. Anaphase:

    • Sister chromatids are pulled apart toward opposite poles of the cell as the spindle fibers shorten.
    • This ensures that each daughter cell will receive an identical set of chromosomes.

  4. Telophase:

    • Chromatids reach the opposite poles and begin to de-condense back into chromatin.
    • The nuclear envelope re-forms around each set of chromosomes, resulting in two distinct nuclei within the cell.

  5. Cytokinesis:

    • Although not technically part of mitosis, cytokinesis is the process that follows mitosis.
    • The cytoplasm divides, resulting in two separate daughter cells, each with its own nucleus and set of organelles.

In summary, the cell cycle consists of interphase (G1, S, and G2 phases) and the mitotic phase (prophase, metaphase, anaphase, telophase, and cytokinesis). Each phase plays a crucial role in ensuring that cells replicate accurately and efficiently.