4 cells resulting from the replication and division of a single parent cell have half the number of chromosomes.
Each chromosome comes near its replicated chromosome pair. Crossing over occurs.
The spindle fibres disappear, and a nuclear membrane forms around each set of chromosomes.
The cytoplasm divides and two new cells form. Each new cell has one duplicated chromosome from each similar pair.
The duplicated chromosomes and spindle fibers reappear in each new cell.
The duplicated chromosomes move to the centre of the cell. Each centromere attaches to two spindle fibres instead of one.
The centromere divides. The chromatids seperate and move to opposite ends of the cell. Each chromosome is now an individual chromatid.
Chromatids do not separate. The two pairs of chromatids move away from each other to opposite ends of the cell. Each duplicated chromosome still has two chromatids.
The pairs of replicated chromosomes line up in the centre of the cell. The centromere of each chromatid pair attaches to one spindle fibre.
