The nucleus is like the remote control center of the cell. It acts as the cell's brain by telling it what to do, how to grow, and when to reproduce. The nucleus is home to the cell's genes. A membrane, a thin layer that allows chemicals to pass in and out to the rest of the cell, surrounds the nucleus.

nucleus (NEW-clee-us), more than one nuclei
Shape: roundish
Found in: almost every cell
Characteristics: contains the DNA that is responsible for the unique traits that all living things have
Importance: it is the control center of the cell and the storage center for DNA

Image credits: Kelvin Chan.