The 4 Stages of Mitosis

Understanding the stages of mitosis is essential for students in biology and related disciplines. Mitosis is how a cell replicates its DNA so that it can divide and form two genetically identical cells. The process of mitosis has four distinct phases: prophase, metaphase, metaphase, and anaphase. Here is a more detailed look at each stage.

Prophase
The first stage of mitosis is prophase. During prophase, the chromatin — the material that makes up chromosomes — begins to condense and thicken into distinct structures called chromosomes. The cell’s nucleus also breaks down during prophase, releasing the nuclear envelope and the nucleolus. Finally, protein structures known as spindle fibers begin to form around the chromosomes.

Prometaphase
Metaphase is the second stage of mitosis. It begins when the spindle fibers attach to the chromosomes at a point called the kinetochore — a specialized structure located near the center of each chromosome. Once each of the chromosomes have been attached to spindle fibers, the nuclear envelope breaks down completely, allowing prometaphase to transition into metaphase.

Metaphase
During metaphase, the chromosomes line up in the center of the cell on what is known as the metaphase plate — an imaginary line that divides the cell equally in half. Each chromosome is still attached to a spindle fiber at its kinetochore.

Anaphase
The fourth and final stage of mitosis is anaphase. Anaphase begins when the proteins that hold sister chromatids together are broken down, allowing the chromatids to separate from one another. As they do so, they are pulled towards opposite poles of the cell by their respective spindle fibers. Once all the chromatids have reached their respective poles, mitosis is complete and two genetically identical cells have been formed.

Conclusion:
Mitosis is how a cell replicates its DNA so that it can divide and form two genetically identical cells. The process of mitosis has four distinct phases: prophase, prometaphase, metaphase, and anaphase. A better understanding of each stage will help students in biology and related disciplines succeed in their studies.