Subunit composition of Eukaryotic & Prokaryotic ribosomes
Ribosome subunits
comprise one or two rRNA molecules,
plus a variable number of proteins.
Combinations of rRNAs and
proteins
typically have a smaller sedimentation rate (S) than their
component parts, due to condensation. In
eukaryotes, the complete 80S monosome comprises a 40S Small Subunit (SSU)
that includes the 18S rRNA,
and a 60S Large Subunit
(LSU)
that includes the 28S, 5.8S, and 5S rRNAs. Prokaryotic ribosomes
are somewhat smaller, but include analogous subunits.
Figure © 2012 TA Brown, Introduction
to Genetics (1st ed.); additional
text © 2013 by Steven M. Carr