Each ribosome has two subunits :
- large subunit (60s)
- small subunit (40s)
The large subunit is made up of proteins and 28S, 5.8S and 5SrRNAs
The small subunit is composed of 18S rRNA complexed with proteins.
Ribosomal genes are present in clusters on the short arms of five human acrocentric chromosome pairs (13, 14, 15, 21 and 22 ) in tandem arrays.
etc.