And any given ribosome itself consists of a small unit and a large unit. So we have the small subunit and a large subunit. So together a ribosome consists of two subunits. Now, these subunits are basically composed of proteins as well as rRNA molecules. So the r RNA molecules are created within the nucleolus and then they are brought into the cytoplasm and in the cytoplasm, as we'll see in just a moment the two subunits the large and the small subunits combined with our mRNA to form our ribosome. Now both prokaryotic and eukaryotic organism contain ribosomes but in eukaryotic and prokaryotic organisms our ribosomes are slightly different so they consist of slightly different small and large subunits.