The nucleus is a highly specialized organelle that serves as the information and administrative center of the cell. It is the most prominent feature of a plant cell, occupying about 10% of its volume. The nucleus has two major functions in a plant cell:

• Storage of DNA: The nucleus stores the cells hereditary material, or DNA, which determines everything about the organism and is also needed for cell division. Most of the nuclear material consists of chromatin, the unstructured form of the cells DNA that will organize to form chromosomes during mitosis or cell division.

• Coordination of cell activities: The nucleus coordinates the cells activities, which include intermediary metabolism, growth, protein synthesis, and reproduction (cell division).

The nucleus is separated from the rest of the cell by a double-layered membrane called the nuclear envelope, which is riddled with holes called nuclear pores that allow specific types and sizes of molecules to pass back and forth between the nucleus and the cytoplasm. DNA replication, transcription, and RNA processing all take place within the nucleus, with only the final stage of gene expression (translation) localized to the cytoplasm. By separating the genome from the cytoplasm, the nuclear envelope allows gene expression to be regulated by mechanisms that are unique to eukaryotes. The presence of a nucleus thus allows gene expression to be regulated by posttranscriptional mechanisms, such as alternative splicing.