Hi. In this video, we're going to be talking about cell to cell adhesion. This video is going to be a little bit boring because most of it is just vocab words. So, I'm going to try and make it as interesting as possible, but a lot of this is just going to be things you have to memorize, in terms you have to memorize. Cell to cell adhesion is pretty much what that means is that neighboring cells need to stick together. And so, in order to stick together, they're going to have to use proteins to do it. There's a bunch of different proteins that we're going to describe that allow these two neighboring cells to stick together. Why do cells need to stick together? Well, because usually, it's because they're trying to work together. So, cells in the same tissue or cells in the same organ, you want those cells to stick together. You don't want your kidney cells to just kind of float off. Right? You want them to stick together, and these cell-to-cell adhesions ensure that these tissues and these organs can actually stay together and have a uniform function or at least can work together for a single purpose. Cells can connect in two ways, depending on the type of molecules that they use. A homophilic connection, or homophilic adhesion, occurs when they use the same type of molecule, which makes sense. We see homo all the time and that equals same, whereas hetero equals different. A homophilic interaction uses the same molecule, this is the most common, whereas a heterophilic is going to be when the cells use different molecules. So, what this looks like is if we have cell number 1 and cell number 2, and these cells need to adhere to each other, a homophilic interaction will be if they both use these red lines. A heterophilic would be if this cell used a red line, and this one uses this blue circle protein. That is the first way to classify these cell-to-cell adhesions, whether it's homophilic, are they using the same things, or is it heterophilic, are they using different things. Now, the most important one that there is tons of these molecules, I mean, hundreds of these different proteins, and we're not going to go through each one because we would be here for the rest of our lives. So instead, we're going to focus on the important ones, and the most important one are these CAMs, or these cell adhesion molecules, and these are the ones used to connect adjacent cells. The most important cell adhesion molecule that you're going to see in your book is called a cadherin. What is a cadherin? It's a protein, but it's also a glycoprotein. Do you remember what glycoprotein means? It means it has a sugar on it. So, this is a sugar protein. It's in the plasma membrane, obviously, if you're going to connect two cells together, then the protein needs to be in the plasma membrane, so it can actually see the other cell. And so, cadherins, they're these sugar proteins, they're in the plasma membrane, and they can bind to connect cells together. Some interesting facts about cadherins, that you know I don't think that you would see on a quiz or probably not, you definitely wouldn't see it on a quiz. They may try to trip you up and give you a really specific question on a test about these. But cadherins, they need calcium to work. So, you drink your milk, so your cadherins work. And then there are three main types. So those are called the E, P, and N. So, endothelial, placental, and neural types, and they have slightly different cells that they interact with. But there are so many more. I mean, dozens, of these nonclassifiable types that exist. Obviously, we're not going to go through all of them. Don't want to keep you all day, but it is important to at least know these three names. That there are three classical types, the endothelial, the placenta, and the neural. So, cadherins, if you are ever planning on taking developmental biology or if you're in a class where your professor just loves talking about development, then this is an interesting fact you might want to know about, and that cadherins are really important for this thing called the epitheliomesenchymal transition. We're not in a development class, so you don't need to know what this is or how this works. But essentially, it's a really important early step in development that helps us to develop properly, and it helps change these mesenchymal cells to epithelial. So, this process leads to the creation of important tissues, like blood, muscle, or bone. But unless you're in a cell biology class, this is not something that you're going to be tested on, but it is something that you will learn about if you ever take a development class. So, cadherins are the most important ones. They're the ones you're going to see most often asked in a test or quiz. But, there are a couple of others that are mentioned in your book. Those are lectins and selectins. So lectins, instead of binding to themselves, they bind to sugars. So, this would be an example of heterophilic type of binding. Right? And then, selectins are again glycoproteins, so they're going to be sugar proteins like the cadherins, and they work specifically on these white blood cells, leukocytes, and endothelial cells. And because they work on white blood cells, you would imagine that they're going to be really important in inflammation. And similarly to cadherins, they have three types, three classes, the endothelial, the platelet, and the leukocyte, so the epl. And sometimes, if you have a really tricky professor, they would like to ask, they'll ask you, you know, what are the three classical types of cadherins, and EPL will be one of them. But remember, this is for selectins, not cadherins. So make sure you get those, classical types, you get those down and make sure you don't get confused about that. And again, like before, there are 100 of these proteins. We're not going to go through all of them, just mentioning the important ones, but know that these aren't the only ones. It's not just cadherins, lectins, and selectins. There are tons, hundreds of these other types of cell adhesion molecules that connect cells together, but we're just highlighting the important ones. So, I think that's it. So, with that, let's turn the page.
Cell-Cell Adhesion: Study with Video Lessons, Practice Problems & Examples
Created using AICell-to-cell adhesion is crucial for maintaining tissue integrity, allowing neighboring cells to stick together using proteins. These connections can be homophilic, where the same molecules are used, or heterophilic, involving different molecules. Key proteins include cadherins, which are glycoproteins requiring calcium for function, and play a role in developmental processes. Other important adhesion molecules are lectins and selectins, which bind sugars and are vital in immune responses. Understanding these interactions is essential for grasping cellular organization and function in multicellular organisms.
Cell-Cell Adhesion
Video transcript
Which of the following is not a type of cell adhesion molecules?
Which of the following CAMs work by binding to sugars on the plasma membrane in order to promote cell-cell adhesion?
Here’s what students ask on this topic:
What is cell-to-cell adhesion and why is it important?
Cell-to-cell adhesion refers to the process by which neighboring cells stick together using specific proteins. This adhesion is crucial for maintaining the structural integrity of tissues and organs, ensuring that cells within the same tissue or organ can work together for a common function. Without proper cell-to-cell adhesion, cells could detach and float away, disrupting tissue function and leading to potential health issues. This process is essential for the uniform function of tissues and organs, contributing to the overall organization and function of multicellular organisms.
Created using AIWhat are cadherins and what role do they play in cell adhesion?
Cadherins are a type of cell adhesion molecule (CAM) that are glycoproteins, meaning they have a sugar component. They are located in the plasma membrane and are essential for binding adjacent cells together. Cadherins require calcium to function and are involved in various developmental processes, such as the epithelial-mesenchymal transition. There are three main types of cadherins: E-cadherin (endothelial), P-cadherin (placental), and N-cadherin (neural). These molecules are crucial for maintaining tissue integrity and facilitating cell-to-cell communication.
Created using AIWhat is the difference between homophilic and heterophilic cell adhesion?
Homophilic cell adhesion occurs when neighboring cells use the same type of molecule to adhere to each other. In contrast, heterophilic cell adhesion involves different molecules being used by the adjacent cells. For example, in homophilic adhesion, both cells might use the same cadherin molecules, whereas in heterophilic adhesion, one cell might use a cadherin while the other uses a different type of protein, such as a lectin. Understanding these types of adhesion is important for grasping how cells interact and maintain tissue structure.
Created using AIWhat are lectins and selectins, and how do they function in cell adhesion?
Lectins and selectins are types of cell adhesion molecules. Lectins bind to sugars, making them an example of heterophilic adhesion. Selectins are glycoproteins that also bind to sugars and are specifically involved in the adhesion of white blood cells (leukocytes) to endothelial cells, playing a crucial role in inflammation. There are three main types of selectins: E-selectin (endothelial), P-selectin (platelet), and L-selectin (leukocyte). These molecules are vital for immune responses and maintaining tissue integrity.
Created using AIWhy do cadherins require calcium to function?
Cadherins require calcium to function because calcium ions stabilize the cadherin structure, allowing it to bind effectively to other cadherin molecules on adjacent cells. Without calcium, cadherins would not be able to maintain their proper conformation, leading to a loss of adhesive function. This requirement underscores the importance of calcium in maintaining tissue integrity and facilitating cell-to-cell communication.
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