In this video, we're going to talk more details about ribosomes, specifically the ribosome subunits. Ribosomes, which recall are the main structure responsible for translation, actually consist of two subunits or two components that are referred to as the small and large ribosomal subunits. Each of these subunits, the small and large ribosomal subunits, are made of proteins and ribosomal RNA or rRNA. It turns out that the ribosomes of prokaryotes differ from the ribosomes of eukaryotes. Notice down below in our image, we're going to be talking about prokaryotic ribosomes on the left-hand side, and on the right-hand side, we're going to be focusing on eukaryotic ribosomes. Again, it's very important to make sure that you're able to distinguish the complete intact ribosome from the other ribosomal subunits that come together. What you'll notice here is that there is a large ribosomal subunit and then there is a small ribosomal subunit. The large and small ribosomal subunit need to come together to form the complete intact ribosome. That's important to keep in mind. Prokaryotes actually have a complete intact ribosome with both subunits combined, referred to as a 70S ribosome. The 70S ribosome of prokaryotes is made up of two subunits: a 50S large ribosomal subunit and a 30S small ribosomal subunit. One thing to note here is that 50+30 does not equal 70 and that's okay. This difference is due to the Svedberg unit, which describes how ribosomes sediment during centrifugation in a complex process. You don't need to worry about the specifics of this unit for our course. Prokaryotes have a 70S, complete intact ribosome that is made up of a large 50S subunit and a small 30S subunit. Eukaryotes, on the other hand, have an 80S intact, complete ribosome when both the large and small subunits are complexed together. This complete intact 80S ribosome in eukaryotes is made up of smaller components: the large subunit and the small subunit. The large ribosomal subunit in eukaryotes is a 60S large ribosomal subunit, and the small ribosomal subunit for eukaryotes is a 40S small ribosomal subunit. Again, 60+40 does not equal 80, but that's how this process works. The process is represented by the numbers 30, 40, 50, 60, 70, 80. To remember this, write down these numbers in their order, put them in pairs, and assign the smaller number to the prokaryotes and the larger to the eukaryotes. This easy method helps you remember the components and the differences between prokaryotic and eukaryotic ribosomes. This concludes our brief introduction to the ribosomal subunits and we'll continue to talk more about ribosomes and the process of translation as we continue to move forward in our course. I'll see you all in our next video.