Prokaryotes contain 70S ribosomes, each consisting of a small 30S and a large 50S subunit. There are three types of rRNA in these subunits: 16S rRNA in the small subunit, 23S rRNA, and 5S rRNA in the large subunit.
In Eukaryotes and Archaea,80S ribosomes are located in their cytosol, each consisting of a small 40S and large 60S subunit. There are four types of rRNA in these subunits: 18S in the small subunit, and 5S, 5.8S and 28S in the large subunit.
The Svedberg unit measures a particle's size based on its sedimentation rate.