<P> The rRNA is transcribed , at a high speed , in the nucleolus , which contains all 45S rRNA genes . The only exception is the 5S rRNA which is transcribed outside the nucleolus . After transcription , the rRNAs associate with the ribosomal proteins , forming the two types of ribosomal subunits ( large and small ) . These will later assemble in the cytosol to make a functioning ribosome . See nuclear export for more about the movement of the ribosomal subunits out of the nucleus . </P>
<P> The rRNA is transcribed , at a high speed , in the nucleolus , which contains all 45S rRNA genes . The only exception is the 5S rRNA which is transcribed outside the nucleolus . After transcription , the rRNAs associate with the ribosomal proteins , forming the two types of ribosomal subunits ( large and small ) . These will later assemble in the cytosol to make a functioning ribosome . See nuclear export for more about the movement of the ribosomal subunits out of the nucleus . </P>
where does the formation of ribosomal subunits occur
where does the formation of ribosomal subunits occur
nucleolus
nucleolus