Overview of Signaling Molecules - Video Tutorials & Practice Problems
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concept
Types of Molecules
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12m
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Hello everyone in this lesson. We are going to be doing an overview of extra cellular signaling molecules. Okay, so we know that signals are incredibly important for cells because cells in a multicellular organism have to communicate with one another to get the job done. Whatever the job maybe we need to send signals between ourselves to communicate between the cells because they're all part of one organism. They need to talk to each other and the way that they're going to talk to each other. Is there going to utilize extra cellular signaling molecules? And there are a ton of extra cellular signaling molecules. We're not going to go over all of the different classes of extra cellular signaling molecules. But we're going to go over some important ones that you are going to go over in your class. But there are more specific molecules as well. But those are probably going to be saved for a later, more in depth class that may specifically be dealing with signaling molecule. Okay, so there are many types of extra cellular signaling molecules and they have numerous different functions. Generally. If there's a specific function that needs to be completed, there is going to be a specific extra cellular signaling molecule for that function. So some examples of signaling molecules are going to include the ones in this box. So we have steroid hormones, gasses, neurotransmitters, peptide hormones, growth factors and I coast annoyance. That one's always hard for me to say. I coast annoyance. Okay, so steroid hormones are going to be things like testosterone estrogen. These are going to be hormones that are going to be made out of lipids and because they are made out of lipids, they can simply diffused through the lipid bi layer into the cell. They have really easy entry into the cell because they are made of lipids which the plasma membrane is also made of lipids. Steroid hormones just slip right on through and they are going to have nuclear receptors. They have receptors that bind to the steroid hormones inside of the nucleus. That's because steroid hormones commonly cause gene transcription to begin. For example, estrogen hormones will go through the plasma membrane into the nucleus, bind to the receptor and then trigger whatever genes to express that deal with. Perhaps female development for estrogen. Okay, so steroid hormones are one very major class of extra cellular signaling molecules. And the thing about steroid hormones is that they are commonly going to affect your entire body or a whole bunch of tissues at once. Okay, we can also have gas is usually don't think of gasses as signals. Usually we think of gasses like oxygen and carbon dioxide as products and waste products of the cellular reactions, but but gasses are very commonly utilized as signaling molecules as well. Specifically one great example is nitric oxide in o nitric oxide can easily diffuse through the plasma membrane because it is so small and it can easily travel throughout the body and it is going to do a whole bunch of things. It can dilate blood vessels, it can change the blood pressure. It's utilized for a lot of things like that to make the blood flow more evenly and things like that. So it actually does signal to cells to tell the cells to do something generally with blood flow. So nitric oxide is a gas, that is also a signaling molecule. Okay, so neurotransmitters are also another big class of extra cellular signaling molecules which I know you've probably heard of before, neurotransmitters are going to be things like acetylcholine, epinephrine dopamine. I mean there's a whole bunch of different ones as well. And basically neurotransmitters are chemical signals that travel from one neuron to the next to transmit a message. So they're going to travel from one neuron to the next. That's why they're known Euro transmitters, their transmitters between neurons and these are going to be chemical signals. Okay, so now we also have peptide hormones. So we talked about steroid hormones which are made of lipids. Now we're going to talk about peptide hormones which are going to be made of peptides now because they're not made of lipids, Peptide hormones cannot diffuse through the plasma membrane. So they are going to have these plasma membrane receptors and growth growth factors are going to be the same way some great examples of peptide hormones and growth factors are going to be insulin endorphins. There's also prolactin which is going to be utilized for lactation whenever a bit baby is around lactation, insulin obviously deals with your pancreas and your sugar concentrations and then growth hormones as well are going to be utilized as extra cellular signaling factors to tell different areas of the body to grow. Okay. And then finally we're going to have Icoast annoyed. Icoast annoyed are going to be lipids but they're going to be lipids that cannot get through the plasma membrane. They're going to be lipids that have a plasma membrane receptor. And these are going to be signals for a lot of things dealing with the immune system, like inflammation, fever, allergies, immune response a whole whole bunch of different things. Um, but that's going to be what are Okay, so now that we've gone over some examples of different classes of molecules, let's look at some examples of their functions. Okay, so what's the point of all these signals? Well, basically what the point of all these signals is is we have to move a message right? We have to relay the signals inside of the cell or outside of the cell. So you're going to have signaling molecules whose main job is to transmit that signal on in a cascade fashion. Then also signals can act as scaffolds to bring signaling proteins together. So basically what this one is saying is it brings signaling proteins together. Once one signal is activate, it's going to activate a whole bunch of other signaling proteins as well. And then when all the signaling proteins come together, the action is going to happen. That flip that switch is going to be flipped And that thing, whatever they're signaling for is going to begin. So basically once one signal turns on and all those other signals are activated, the action will begin whatever the cell is told to do, it will begin to do. Also these sick signaling molecules are great for transducer signals into a different form. This is going to be something like changing the signal from an extra cellular signal to an intracellular signal. So if a extra cellular signal binds to its receptor on the outside of the cell, well then that receptor will trigger an interior signal inside of the cell to begin signaling inside of the cell. So that's transaction of the signal or changing of the signal. And really, really important is amplifying the signal through signaling cascades. We'll talk more about this later, amplifying the signal is very, very important. Cyclic A. M P is going to be a great example of a messenger that amplifies the signal basically it makes the signal really giant and there's a whole bunch of signaling molecules that are transmitting the same signal and this is going to cause big changes in the cell. Also of course signaling molecules are utilized to spread other signals anchor other signals or modulate other signals depending on what the cell needs to do. So that's just a basic overview, generalization of what signaling molecules are going to accomplish. Okay, so now one more thing before we end our lesson is that signaling molecules act over different distances depending on the type of signal you're working with will tell you how far that signal can go. Obviously there are signals that work really long distances in the body. Then there are some that work kind of only locally in the same tissue, but not the whole body. And then there are some signals that really don't go very far whatsoever. So there are different types of signals who have different distances which they can relay that's signal. So the first one we're going to talk about is we're going to talk about the endocrine molecules. The endocrine molecules are the hormone molecules. Your hormone system is also called your endocrine system. And these are going to be the really big bad awesome signaling molecules because they're incredibly long distance and that's because they utilize the circulatory system to transmit. That signal hormones are carried through the circulatory system through the blood to get to really far distant cells. So a lot of cells can be communicated with at one time. Your endocrine system is your long distance signaling system. So long distance. Remember that's very important and remember these are going to be um molecules like testosterone and estrogen which can affect the entire body. So they have to be long distance signals. Then we have our peregrine system, The peregrine molecules are going to be close proximity or local mediators. So while endocrine is like the long distance signals, Para Quran is kind just local, short distance signaling not very far. And these are going to be things like neurotransmitters and growth factors, neurotransmitters travel from one cell to the next. They don't go very far right neurotransmitters, one neuron to the next and that's all that they do. So they're very localized in that particular area. Okay, so now last but not least we have the auto crash in auto cringe can be kind of confusing to some students. It did confuse me as well. These are going to be molecules that are sent from the cell to the same cell. So auto Quran means self signaling. These are molecules that are actually being made by one cell. So let me show you what that looks like. So let's say that this is our cell and it makes this signal. Well this signal is going to to be utilized to signal the same cell which sounds kind of odd but it is utilized for certain purposes. Um I carcinoid are going to be utilized in this manner. They are going to be auto Quran molecules for the most part, so oughta Quran is the most local, most short distance signaling because basically the cell is signaling to itself. So we have endocrine, para Quran and Quran and this is going to be one of the diagrams that will show you this, you can see endocrine right here is being utilized to do the really long distance from one cell all the way to the other, It's the longest distance signaling. And then we are going to have the peregrine system which just goes from one cell to the next kind of like neurons do. And then we're going to have the auto Quran which goes from this cell back to its self. So one cell is signaling to itself, which is kind of funny to understand, but it is important for the cell to get cellular things done whenever it has to signal to itself. So endocrine, peregrine and autocrat are going to need to know those and you're going to need to know the basic functions of signaling molecules and the basic classes of signaling molecules. Okay, everyone, let's go on to our next topic.
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concept
Cell Response
Video duration:
4m
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Okay, so now we're going to talk about the cell response to signaling molecules. So once a signaling molecule reaches a cell, what happens? And what does the cell do with that information? Right. So let's say a signaling molecule has come in and it is activated A receptor, its binding to that receptor. And now the receptor has to tell the cell what to do. So how does it do that? Well, it chooses one of two ways. The first is that it takes that signal and it says I'm giving it to you another protein and that passes that on to the rest of the cell. So it says I'm activated right now and I'm going to activate something else. And then it's not gonna be my problem. I'm gonna let that other protein deal with it. So what that means is that a receptor takes that signal and then it transmits transmits it to another nearby enzyme some of enzyme and that enzyme is going to be called a second messenger because it wasn't the first messenger, right? The first one to receive the signal, it got that signal from the receptor. So it's the second messenger. That second messenger can go on to activate other messengers on down the sale. But it's going to keep signaling away from the receptor. So the first way is the receptor doesn't deal with it. It passes it off to another protein. The second way is when a receptor is activated, it wants to be all up in all the business and wants every type of interaction it can get. So what it does is it sends out these kind of signals and all these proteins come in and attach onto that receptor and then they themselves are activated. So you get this whole scaffold of proteins that are surrounding this receptor all of them become activated. They go on to cause signaling more signaling. So the second way is that the receptor acts like a recruiting station or a train station where all these proteins are coming in getting activated and then going out into the cell. So when a receptor is activated it either passes it off to something else or it's really all involved. And all these proteins come in and bind. Now you can imagine that the cell has to have a variety of different ways of responding to signals. It has to be able to recognize a variety of signaling molecules and pathways. So this is a huge network. There's so many hundreds of thousands even of signaling molecules that bind differently to different receptors. And then once that receptor is activated it can either send that off to something else or act as a recruiting hub. So there's so many proteins that are involved in any type of cell signaling response. And not only that if you take one cell and a different type of cell and expose them to the same signaling molecule, they can have widely different responses. So an example of this is acetylcholine now, do you remember what acetylcholine is a neurotransmitter T. T. E. R. And if you take a a cardiac muscle from the heart and you take skeletal muscle from any of your other muscles and you expose those cells to acetylcholine they're going to respond differently. The heart is going to decrease its contractions while the skeletal muscle is going to increase its attractions. So that same molecule probably binding to similar proteins causes very different reactions because of all of the different proteins that come in and signal once the signaling molecule has gotten into the cell and process and the cell is processing that signaling pathway. So just to show you an image of these methods of receptor signaling, we have the first method where the receptor does not want to be involved. So what happens is a signaling molecule comes in maybe activates this receptor and then this receptor says not my problem, it's yours now. Okay. And so that second messaging messenger that signaling enzyme goes on and it takes that signal to the rest of the cell and does whatever it's gonna do to activate it and allow the cell to respond. The second pathway is if we have a signaling molecule come in it starts recruiting other proteins. It may even recruit another of itself. So a copy of itself to dine arise. It can do that. It often does that. And then once this happens we get a variety of proteins coming into this train station of this recruiting station all of them are going to become activated and they're going to go and signal further down, or they're going to travel away and do something else. There's so many different actions that these proteins can take inside the cell to allow the cell to respond to that signaling molecule. Okay, so with that, let's move on.
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Problem
Problem
Which of the following is not a classification of signaling molecules?
A
Autocrine
B
Paracrine
C
Endocrine
D
Lyoncrine
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Problem
Problem
Signaling molecules work only through signaling cascades.
