The nucleus contains most of the DNA in the cell. It is recognizable by the protein complexes known as nuclear pores embedded in its outer membrane. These pores are responsible for facilitating the flow of biological materials in and out of the nucleus.

Transcription occurs within the nucleus. Through this process the information in the cell's DNA is used as a template to create RNA. The RNA is then modified into one of three types: mRNA, tRNA, or rRNA.

Pre mRNA must be spliced to remove non-coding sections called introns. The remaining sections, called exons, are then spliced together.

After splicing, pre-mRNA is processed further by the addition of a methylated cap and a poly-A tail.

After being spliced and modified, the finished mRNA strand leaves the nucleus through a nuclear pore and enters the cellular cytoplasm.