The three major parts of the cell are the cell membrane, the nucleus, and the cytoplasm. The cell membrane functions as a selective semipermeable membrane and separates the cell from its external environment and from the neighboring cells. It also regulates the passage or transport of certain molecules into and out of the cell, and prevents the passage of others. The nucleus can be defined as the most important organ organelle within the cell. Its functions are to control cellular activities and to facilitate cell division. It is surrounded by a nuclear membrane and contains DNA and protein arranged in a loose state known as chromatin, which can further condense into structures known as chromosomes when the cell is ready to divide. Chromosomes