In early stages, the nucleolus and nuclear membrane disappear.
Chromatin (DNA) condenses into chrom osom es. (Each chromosome
consists of two identical sister ch rom atids joined at centrom eres.)
Later, centrosomes migrate to opposite ends of the cell and form an
array of microtubules called the mitotic spindle. The microtubules
attach to the centromere of each chromosome and to the centrioles of
the centrosome. Prophase is the longest phase of mitosis.
Chrom osom es line up along the
middle of the cell and form the
A n ap h ase:
The mitotic spindle shortens and pulls the sister
chromatids of each chromosome to opposite ends
of the cell. This is the fastest phase of mitosis.
Cells Carry Out Many Processes 69