Nucleus
The nucleus is a organelle found in living cells. It contains most of the cell's genetic material and is organized as multiple long molecules in along with a large variety of proteins, such as histones, made to form chromosomes. The genes within these chromosomes are called the cell's nuclear genome. The function of the nucleus is to maintain these genes and to control the activities of the cell by controling the gene expression. In short, the nucleus is the control centre of the cell.