What occurs to the nuclear lamina at the start of mitosis?

At the start of mitosis, the nuclear lamina disassembles due to phosphorylation. The nuclear lamina is a dense fibrillar network composed of intermediate filaments and proteins that provides structural support to the nucleus. During prophase, one of the key steps is the phosphorylation of lamins, the main proteins that make up the nuclear lamina. This post-translational modification leads to the disassembly of the nuclear lamina, causing the nuclear envelope to break down. This breakdown is essential for the mitotic spindle to interact with the genetic material without obstruction, allowing for the proper segregation of chromosomes during cell division. The process of phosphorylation weakens the interactions between lamin proteins, facilitating this disassembly. Thus, the correct answer highlights the critical change in the nuclear lamina that enables the cell to proceed with mitosis effectively.