Cell Junctions - Video Tutorials & Practice Problems
On a tight schedule?
Get a 10 bullets summary of the topic
1
concept
Cell Junctions
Video duration:
5m
Play a video:
Video transcript
In this video we're going to begin our lesson on cell junctions and so what's important to note is that neighboring cells of eukaryotic organisms are able to directly interact with one another using cell junctions And so really there are 4 main types of cell junctions that are used to link adjacent cells together. And so down below what we have is a table that lists each of these types of junctions in the left column and then it has a description of each junction in the right column. And then down below what we have are images of each of these 4 junctions. Now notice that the first three junctions in the first three rows of this table correspond with junctions that are found in animal cells and the very last junction in the table corresponds with the junction found in plant cells, so that's important to keep in mind. And so the very first junction that we have in this list is, the tight junction. And as its name implies, the tight junctions are going to be holding cells very, very tightly together. So tightly that it is going to create a leak proof barrier. And so these tight junctions are really just membrane proteins that link cells very very tightly together, so tightly that it creates these leak proof barriers. That way when you drink a glass of lemonade, that lemonade does not just leak or seep right between your cells and end up on the floor. And so, if we take a look at our image down below on the left hand side over here, notice we're showing you the tight junction. And so each of these blue, squares that you see, in the background, they represent the membranes of 2 adjacent cells. And what you'll notice is that the tight junctions, again, are going to utilize these protein structures in orange in order to hold the two cells very, very tightly together so much so that it creates a leak proof barrier. And so when liquids, are here they are not able to see through so they're not able to get in between and leak through. Instead, this creates a leak proof barrier so the liquids can be retained on one side. Now the next junction that we have are called anchoring junctions, otherwise known as desmosomes. And so these anchoring junctions or desmosomes are going to be intermediate filaments that anchor neighboring cells together using complex protein structures. And so if we take a look at our next image here, which you'll see is we have the anchoring junction. And so, once again, the anchoring junction is going to use this complex, protein structure here in order to hold these 2 adjacent cells together. Now the anchoring junction is not necessarily leak proof and so liquids are able to seep their way in between here, and that is somewhat what distinguishes them from these tight junctions. Now the next junction that we have are the gap junctions and as their name implies, the gap junctions are going to create protein channels that create a gap between the two cells and therefore they are going to connect the cytoplasm of the 2 neighboring cells. And specifically these are going to be animal cells. And so if we take a look at our image down below, this junction right here in blue represents the Gap Junction. And notice that the Gap Junction again, it creates these protein channels, basically these tunnels and the tunnels are actually directly linking the cytoplasm of the 2 neighboring cells. And so that allows the cells to exchange nutrients and things of that nature. Now again, the first three junctions that we've discussed, the Tight Junctions, the Anchoring Junctions or the Desmosomes, and the gap junctions are all junctions that are features of animal cells. And this very last junction that we're going to talk about, the plasmodesmata, is going to be a junction of plant cells and so the plasmodesmata are pretty much analogous to the gap junctions and so the plasmodesmata are going to create gaps in the cell walls of plant cells that connect the cytoplasm again of 2 neighboring plant cells or several neighboring plant cells. And so if we take a look at our image down below, what you'll notice is on the far right hand side, we're showing you an image that has multiple plant cells that are neighboring and notice that each of these plant cells have these plasmodesmata, basically these gaps or these openings in their cell wall that allow the neighboring cells to exchange nutrients. And so, that can be beneficial to these plants in many different ways. And so this here concludes our brief lesson on cell junctions and we'll be able to get some practice applying these concepts as we move forward. So I'll see you all in our next video.
2
Problem
Problem
Which of the following are only in plant cells and not in animal cells?
A
Gap junctions.
B
Desmosomes.
C
Plasmodesmata.
D
Tight junctions.
3
Problem
Problem
Ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through: