| Term | Definition |
| DNA | the nucleic acid in the nucleus that codes for the specific amino acid sequence of proteins |
| chromatin | DNA in a threadlike form, found in the nucleus |
| chromosomes | chromatin which has condensed or coiled to form rodlike structures |
| nuclear envelope | a double membrane surrounding the nucleus |
| nuclear pores | openings that allow proteins to enter the nucleus and ribosomal subunits to leave the nucleus |
| nucleolus | the organelle within the nucleus that produces the ribosomal RNA |
| rRNA | the type of RNA that is produced by the nucleolus, and eventually forms the ribosomal subunits |