Once they have all taken their places, the chromosome pairs quite rapidly move apart, as if some powerful chromosome magnet had been placed on each side of the cell. Limbs trailing, the chromosomes move towards opposite ends of the cell, forming two clumps that are separated when the cell divides. Although Flemming described the movements of the chromosomes accurately, he had no idea what this dance meant. For all Flemming or any of his contemporaries knew, the chromosomes were dancing for the sheer joy of being a chromosome. Today, we know they are dancing to distribute their DNA to new generations of cells.
New organisms get their chromosomes from their parents.
For organisms that reproduce asexually, such as bacteria, algae, and sometimes sea anemones, reproduction is as simple as dividing in two. Distributing chromosomes to the next generation merely involves cell division. But for organisms, like humans, that reproduce sexually, the task of handing down chromosomes to the next generation is more complex. In meiosis, a cell copies its chromosomes and then divides twice, producing four sex cells. In humans, egg and sperm cells each have 23 chromosomes.