nucleus (biology)

In biology, the central, membrane-enclosed part of a eukaryotic cell, containing threads of DNA. It is found in both plant and animal cells. During cell division the threads of DNA coil up to form chromosomes. The nucleus controls the function of the cell by determining which proteins are produced within it. It is where inherited information (see inheritance) is stored as genes. Because proteins are the chief structural molecules of living matter and, as enzymes, regulate all aspects of metabolism, it may be seen that the genetic code within the nucleus is effectively responsible for building and controlling the whole organism.

The nucleus contains the nucleolus, the part of the cell where ribosomes are produced. Movement of molecules into and out of the nucleus occurs through the nuclear pores. An average mammalian nucleus has approximately 3,000 pores.