Western Governors University (WGU) BIO1010 C190 Introduction to Biology Practice Exam

During prometaphase, the nuclear envelope breaks down, which is a crucial step in the process of cell division, specifically during mitosis. As the cell transitions from prophase to prometaphase, this breakdown allows the microtubules from the mitotic spindle to attach to the chromosomes at the kinetochores, which are specialized protein structures formed on the centromeres of the chromosomes. This attachment is essential for the proper segregation of chromosomes into the daughter cells. The dissolution of the nuclear envelope creates an environment where the chromosomes, which have already condensed and become visible during prophase, can be effectively moved and organized within the cell in preparation for separation.

Restoring the nuclear envelope occurs later in telophase, after chromosomes have been segregated to the poles of the cell, emphasizing the importance of its breakdown during prometaphase for successful mitosis.