Nucleus is a structure that directs the cell's activities in a organism including reproduction.
Explanation:
The nucleus is considered to be the main structure that contains the cells gene and controls cell growth and reproduction.
The nucleus is known as the cell's control center which is round and small. It contains chromosomes which are said to be the house of DNA.
At the time of the reproduction, the nucleus is capable of dividing and forming separately.
There is a nuclear membrane that is said to be the double layer envelope in which nuclear matrix is present and also it isolates the nucleus from the cytoplasm.