Now, at the center, at the heart of our nucleus, is a region of specialized region known as the nucleolus. And the nucleolus is the region where we synthesize incomplete ribosomes, the ribosomes that end up being in this region, the endoplasmic reticulum, or as free ribosomes found inside the cytosol, which we'll talk about in just a moment. So let's move on to this region here. So we have the cell membrane, this is our nucleus, the nuclear envelope that contains those nuclear pores, as well as our DNA that is found inside the nucleus. And this is our region known as the nucleolus. Now let's move on to region number four and region number five.