Certain parts of the brain govern specific functions. For example, the cerebellum is involved with coordination; the hippocampus with memory. Nerve cells (neurons) are the basic unit of communication in the brain.
Eukaryotic organisms use mitosis to reproduce sexually. In mitosis, the parent cell is divided into two daughter cells which be identical to the parent cell. Edit
Meiosis is the type of cell division that allows sexual reproduction, since it reduces the number of chromosomes of the species to a half, making the combination of two gametes to form a new individual possible. (In some organisms, meiosis creates haploid gametophytes that by means of mitosis generate gametes.