Prometaphase

Prometaphase is a stage of mitosis in eukaryotic cells. It follows prophase and precedes metaphase. During prometaphase, several key processes occur that are crucial for the successful division of the cell.

Key Events in Prometaphase

Breakdown of the Nuclear Envelope

In prometaphase, the nuclear envelope that encloses the nucleus disintegrates. This breakdown allows the mitotic spindle to interact with the chromosomes. The disassembly of the nuclear envelope marks the transition from prophase to prometaphase.

Chromosome Condensation

Chromosomes, which have already been duplicated during S phase of the cell cycle, continue to condense and become more visible under a microscope. Each chromosome consists of two sister chromatids joined at a region called the centromere.

Spindle Fiber Attachment

The kinetochore, a protein structure on the chromosome, forms at the centromere. Spindle fibers, which are composed of microtubules, attach to the kinetochores. This attachment is crucial for the movement of chromosomes during mitosis.

Chromosome Movement

Once the spindle fibers attach to the kinetochores, the chromosomes begin to move. They are maneuvered by the spindle apparatus towards the center of the cell, a region known as the metaphase plate. This movement is essential for the alignment of chromosomes during the subsequent metaphase.

Importance of Prometaphase

Prometaphase is critical for ensuring that each daughter cell receives an identical set of chromosomes. The proper attachment of spindle fibers to kinetochores and the alignment of chromosomes are vital for the accurate segregation of genetic material.

Prometaphase

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  Prometaphase

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  Stages of early mitosis in a vertebrate cell with micrographs of chromatids

See Also

• Cell cycle
• Mitosis
• Prophase
• Metaphase
• Anaphase
• Telophase

References

• Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K., & Walter, P. (2002). Molecular Biology of the Cell. 4th edition. New York: Garland Science.
• Lodish, H., Berk, A., Zipursky, S. L., Matsudaira, P., Baltimore, D., & Darnell, J. (2000). Molecular Cell Biology. 4th edition. New York: W. H. Freeman.