In this video, we're going to talk about how pili can be used for cell motility or cell movement. Pili are actually involved in two types of cell motility that we have numbered down below: 12. The first type of cell motility in which pili are involved is twitching motility. Twitching motility can be described as the pili itself extending from the cell, attaching to a surface, and then retracting in order to drag the cell forward. During this period, the cell is actually moving towards its destination in a twitching-like or a jerking-like motion. This is where it gets its name, twitching motility. Notice that with this, the bacteria will be extending its pilus, attaching its pilus to an area that's further along the destination, and then retracting its pilus to pull the bacterial cell forwards in the direction of its movement. It is going to be a twitching or a jerking type of movement that is not going to be continuous and will appear very twitch-like.
On the other hand, the second type of motility that pili are involved in is gliding motility. In gliding motility, there is going to be a smooth movement that does not have a twitch-like or a jerk-like effect. The movement of the cell along the axis will be smooth. There are motor proteins involved with this process that will attach to the surface surrounding the cell. However, the exact mechanism of this is unknown. Looking at our image down below at the gliding motility, you will notice that there are motor proteins involved, and the pili is also going to be involved in some way, but ultimately the cell movement is going to be very smooth and will not be twitch-like. You can see we have the motor proteins labeled here. The significant difference is that both twitching motility and gliding motility somehow involve a pilus. Twitching motility is going to be in a twitch-like or jerk-like fashion, whereas gliding motility is going to be in a smooth-like fashion.
This concludes our brief introduction to cell motility by pili, and we'll be able to get some practice as we move forward. I'll see you all in our next video.