Cell Junctions

in this video, we're going to begin our introduction to sell junctions. And so neighboring cells of eukaryotic organisms are able to directly interact with one another by using cell junctions. Now, really, there are four main types of cell junctions that you all should know that link adjacent cells together. And so notice down below. Here, we're showing you this table of the four types of cell junctions that you all should know on. So you could see the junction type over here on the left hand side, and then the description of each of the junctions over here on the right hand side and then down below. What we have are some images of each of these four junctions. And so the very first junction that you all should know are the tight junctions, which are going to be membrane proteins that link cells together in a tight fashion in order to create leak proof barriers. And so when you drink a glass of lemonade, that lemonade does not leak in between yourselves and end up on the floor. And that's all thanks to tight junctions which create leak proof barriers. So if we take a look at our image down below, over here on the left hand side, notice that we're showing you an example of a tight junction. And so notice that each of these yellow barriers that you see here and here represent the plasma membrane of two different cells. And, uh, here in the gray circles that you see, um, these are representing proteins. They're tightly linking thes two cells together to create a leak proof barrier. So that way, liquids cannot really make their way on bleak in between the cells because they're so tightly held together, so liquids will not be able to see through. And once again, tight junctions create a leak proof barrier. Now, the second type of junctions you all should know are the anchoring junctions or, in other words, sometimes referred to as Dez Mazzone's. Now the anchoring junctions are intermediate filaments that, as their name implies with the anchoring, are going to anchor neighboring cells together, using complex protein structures and so down below. Here, you can see that we're showing you an image of anchoring junctions, also known as Dez Mazzone's, and so you can see that they use these complex protein structures here made of intermediate filaments to essentially link to neighboring cells together. Now, which you'll notice is that anchoring junctions may not be leakproof, so things can still seep in between the cells, unlike tight junctions, which are so tightly held together that they are leak proof. Now moving on the third type of cell junction that you all should know are the gap junctions, which, as their name implies, these air protein channels that are going to create a gap between two cells. So they're going to connect the two cytoplasm of to animal cells. And so when we take a look down below over here, notice that we're showing you an example of gap junctions and so notice that these are going to be proteins that literally create channels between the two cytoplasm of two neighboring cells. So once again, the two yellow barriers that you see here represent the cell membranes of two neighboring cells, and then the protein channels that you see here notice that there literally creating a poor or a gap between the two membranes so that they can exchange nutrients and things of that sort. And so what's important to note is that the first three junctions that we talked about. The tight anchoring and gap junctions are all on Lee found in animal cells. And so then the question becomes, Well, what about plant cells that have cell walls? How do they create sell junctions? And so that's exactly what this fourth and last junction is all about. The plasma does Mata. And so these plasma Dez Mata are basically the plant version of gap junctions. And so plasma Dez Mata are going to be gaps in the cell walls that connect the two cytoplasm of two neighboring plant cells. And so, once again, the plasma does Mata are specifically found in plant cells, whereas the other three here, the tight, the anchoring and the gap are all found in animal cells. So if we take a look at our image down below of the plasma, does Mata notice that we're showing you three neighboring plant cells right here? And they have gaps in their cell walls that we're showing you here that basically allows these cells these plant cells, to exchange nutrients with one another. Uh, in this type of fashion connecting the two cytoplasm or all of the cytoplasm of the neighboring plant cells. That is what plasma does model allow for. And so this here concludes our introduction to sell junctions, and we'll be able to get some practice applying these concepts as we move forward in our course. So I'll see you all in our next video.

Which of the following are only in plant cells and not in animal cells?

• A. Gap junctions.
• B. Desmosomes.
• C. Plasmodesmata.
• D. Tight junctions.

Ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through:

• A. Gap junctions.
• B. Desmosomes.
• C. Tight junctions.
• D. Intermediate filaments.
• E. Plasmodesmata.
• F. Actin filaments.