What describes the prometaphase of mitosis?

During prometaphase of mitosis, the key event is the attachment of spindle microtubules to kinetochores. Kinetochores are protein structures located at the centromeres of chromosomes, and they play a critical role in chromosome movement. This attachment is crucial as it enables the chromosomes to be aligned properly at the metaphase plate in preparation for segregation into daughter cells.

In this phase, the nuclear envelope has already broken down during prophase, which allows spindle microtubules to access the chromosomes. The chromatin has condensed into distinct structures known as chromosomes, making them visible under a microscope. However, the actual pulling apart of chromosomes occurs in the subsequent anaphase. Therefore, the activity of spindle microtubules binding to kinetochores during prometaphase is fundamental for ensuring that each daughter cell receives the proper number of chromosomes during cell division.