All cells reproduce by growing to a larger size, and then dividing to form two daughter cells, which then begin to grow, so that they are also can divide.
Normal cells have the diploid number of chromosomes, although there are some exceptions found in reproductive systems, where gametes are normally haploid.
In 1875, Eduard Strasburger accurately described the processes of mitotic cell division. It was given the name mitosis by Walther Flemming in 1882.
In 1885, Walther Flemming reported seeing sister chromatids passing to opposite poles of the cell during mitosis, drawing attention to their importance.
Processes which occur in the nucleus include meiosis and mitosis: nucleic acid is copied in these processes, so each new cell carries the full set of genes.
In meiosis, pairs of homologous chromosomes line up and crossing-over happens at the chiasma, where portions of the two chromosomes are exchanged.
The result of meiosis is an independent assortment of genes through recombination. After meiosis, gametes have the haploid number of chromosomes.
Most mistakes in the copying of genes, the plans for a cell in the nucleus, are harmful to the cell that carries them, but very rarely, they are useful.
When cells divide to make new cells, they must copy all of the parts in the cell to make sure that each daughter cell is fully equipped, or else they will die.