In this video, we're going to begin our review of prokaryotic surface structures. We're only going to review information that we've already covered in our previous lesson videos. If you're feeling really good about the information we've covered, then feel free to skip this video. However, if you're looking for a little bit of extra help, then stick around because this review video could be helpful for you. Notice that we have a table down below of all the different surface structures that we covered in our previous lessons. We're starting here with the glycocalyx, which recall is the sticky gel-like polysaccharide layer that surrounds cells. The glycocalyx comes in 2 forms, which is why we have this bracket here on these two rows. The first is the capsule, a highly organized layer of polysaccharides that is tightly anchored to the cell. You can see the image from our previous lessons showing the organization of the capsule. The slime layer, on the other hand, is a form of glycocalyx that is much less organized. It's a less organized layer of polysaccharides and is more loosely attached to the cell. You can see the less organized image of the slime layer that we used in our previous lesson videos.
Next, we have the pili. We said that the pili are long protein filaments that extend from the surface of the cell and can have varied functions. Primarily, they serve either for motility purposes, allowing for twitching motility and gliding motility, or as a sex pilus to allow for conjugation, which is the transfer of DNA through direct contact between bacterial cells. Next, we have the fimbriae. Recall that the fimbriae are short filaments that extend from the cell's surface, primarily used for attachment purposes. They allow bacterial cells to attach to each other and to other surfaces. The fimbriae are important for the formation of biofilms, which are communities of microbes that live together within an extracellular polymeric substance.
Next, we have the hamuli. Recall that the hamuli are short protein filaments only found in archaeal cells. This is specific to the archaea. They act as short grappling hooks that allow archaea to adhere to each other and also adhere to other bacteria and such. The last structure we talked about was the flagella. The flagella is a long protein filament important for driving swimming motility, or the movement of cells in a run-and-tumble type of fashion. We have the structure and image representing the structure of the flagella over here on the right.
This concludes our brief review of the prokaryotic surface structures. In our next video, we'll be able to talk more about the flagellar motilities that we discussed in our previous videos. I'll see you all there.
