The genetic material DNA resides mainly in the nucleus, which is surrounded by a double membrane with numerous openings called nuclear pores.
When the cell is not dividing, DNA is complexed with proteins in dispersed fibers called chromatin, which condense into visible chromosomes during cell division.
The nucleolus is the region where ribosomal RNA (rRNA) is made and ribosomes are initially assembled.
Other organelles reside in the cytoplasm.
Surrounding the cell is a plasma membrane. In plant cells, a cell wall made of cellulose surrounds the membrane.