So let's take a look at the differences between our subunits. So let's begin with eukaryotic organisms. So in eukaryotes our small subunit is the 40s while the large subunit is the. They combine to form a unit known as the. Now in prokaryotic organism, the small subunit is the, large subunit is the they combine to form the. Now, the question that you might be asking is what exactly is the s?