Organelles and Their Functions. The nucleus is arguably the most important organelle in the cell. It is the control center, telling all of the other organelles what to do and when to do it. The nucleus also contains all of the cell's genetic material, or its DNA.This material has all the instructions the cell needs for making proteins and many other important molecules.ysosomes also break down proteins, lipids and carbohydrates into more usable forms for the cell. Living things need energy in order to perform daily functions. The mighty mitochondria are the organelles that make energy by converting food into more usable forms for the cell.