what happens in prometaphase

Prometaphase is the stage of mitosis when the nuclear envelope breaks down and spindle fibers attach to chromosomes, so the chromosomes can start moving toward the cell’s center.

Quick Scoop

During prometaphase:

• The nuclear membrane disassembles.

• Kinetochores form on each chromosome at the centromere.

• Spindle microtubules attach to those kinetochores from opposite poles of the cell.

• Chromosomes move back and forth until they begin lining up at the metaphase plate.

Why it matters

This stage helps make sure each daughter cell gets the correct set of chromosomes. The cell usually does not move on to metaphase until the chromosomes are properly attached, and the spindle checkpoint helps prevent mistakes.

In one sentence

Prometaphase is basically the “attach and organize” phase of mitosis: the nucleus opens up, spindle fibers grab the chromosomes, and the chromosomes get positioned for metaphase.