in this video, we're going to introduce osmosis. And so osmosis is a type of passive diffusion, which means that absolutely no energy is required for osmosis to occur now, as Moses is defined as the passive diffusion of a solvent across a semi permeable membrane now recall that solvents are substances that dissolve other substances and usually in biology. The solvent is going to be water, and so really, we can define osmosis as the passive diffusion of water across a semi permeable membrane such as ah, biological membrane or a cell membrane. Now, really, the direction that water will flow across that semi permeable membrane or biological membrane will depend on the tennis ity of the solution. And so the tennis ITI is defined as the relative concentration of salute dissolved in the solutions. And when it comes to tennis ity, really, there are three terms that you all should know, and we have these three terms down below and which will notice about all three of these terms is that they all end in tonic and tonic is just referring to the tennis ity. And so what you'll notice is the difference between these three terms is going to be the prefix that comes right before. And so that's why we have the prefix as interactive. And so the first term that you all need to know When it comes to tennis, ITI is the term Hypo Tonic Now. Hypo is a prefix that means low, and it even rhymes with low hypo low. And so Hypo Tonic Solutions are going to have lower Salyut concentrations. Now the second term that you all should know is isso tonic and ISO is a prefix that means equal and so isotonic solutions are going to have an equal Salyut concentration and the third and final term that you need to know when it comes to tennis. ITI is hyper tonic solution and hyper kind of sounds like hypo, but hypo round rhymes with low but hyper does not rhyme with low, so hyper is actually going to mean higher saw you concentrations. And so what you'll notice is that lower, equal and higher are all words of comparison. Something can't be lower unless it's lower than something else. Something can't be equal unless it's equal to something else, and something can't be higher unless it's higher than something else. and so essentially, what we're saying is that lower, equal and higher are words of comparison. You need to be comparing at least two regions and the same goes with hypo ISO and hyper tonic. You need to be using these words when you're comparing two regions. Now, the two regions that were typically going to be comparing are the inside of the cell. That's region number one and the second region that will be comparing. Is the region on the outside of the cell or the surrounding solution outside of the cell so down below? In our example, notice that it's asking us to label the tennis city of the outside solution on the outside of the cell with respect to the solution on the inside of the cell. So we need to be comparing the outside solution on the outside of the cell with the inside of the cell, which would be over here, and we'll be doing that in each of these three scenarios down below. So when we take a look at this first scenario over here on the left hand side, notice that there are these green salutes and there are only two green salutes on the outside, whereas on the inside there's a much higher concentration of these grain salutes. And so because the outside has a lower saw you concentration than the inside, we can label the outside solution. We're labeling the outside solution here and the outside is lower, so it's going to be Hypo Tonic. The outside solution will be hypo tonic because it has a lower solute concentration than the inside of the cell, which has a higher solute concentration. Remember the salutes Here are the green circles. Now moving on to this scenario here in the middle again, we're gonna be labeling the outside solution. And what you'll notice is that the outside solution has a concentration that's pretty much equal to the concentration of solid on the inside. And so because the outside solution and inside solution have equal saw you concentrations, that means that the outside solution will be isotonic with respect to the inside. So in here in the middle, we can label this as ISO tonic. Thea outside is isotonic with respect to the inside and then notice over here and the final, uh, image over here on the right hand side. Once again, we're labeling the outside solution and noticed that the outside solution has a much higher concentration than the inside. And so that means that the outside, because it's higher, it's going to be hyper tonic. And so we can label the outside solution hyper tonic here, and that will be the outside solution once again because it has a higher concentration of solute than the inside. And so now what we can do now that we've labeled the outside solution with all three of these terms and remember the outside solution is gonna be here in all three cases, we can now try to label the inside solutions for each of these. And so when you take a look at the inside of these, notice that the inside here has a higher concentration with respect to the outside, which has a lower concentration. So the inside of the cell here because it has a higher consul, you concentration. It's going to be hyper tonic so we can label the inside here as hyper. I'm just gonna put hyper here just to save some space, but it would be hyper tonic eso Now let's label the inside over here. Well, the inside here has an equal saw you concentration with respect to the outside. So that means that the inside is also going to be isotonic. But I'll just put ISO here just for short. And then over here, labeling the inside solution noticed that the inside here has a lower solute concentration than the outside, which has a higher salt concentration. And if it has, if the inside has a lower solute concentration, that means it will be hypo tonic on the inside. And so here we can label the inside as Hypo Tonic, and so you can see that these words are words of comparison. Once again, you must be comparing to regions on usually those regions are going to be the outside of the cell with the inside of the cell. And so this year concludes our introduction to osmosis and as we move forward, will be able to continue to talk. Maura, Maura about now that we know about the tennis city, we can talk about the direction of water flow so we'll talk more about that in our next video, and I'll see you guys there
Osmosis Example 1
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all right. So here we have an example Problem that's asking, What is the tennis ity of the outside solution in comparison to the inside of the cell? And we've got these four potential answer options down below now, of course, when we look at Option D, it says Electro tonic, which is not a word that we described in our last lesson video. So for sure, we know that we can eliminate answer Option D. But hype, a tonic, isotonic and hyper tonic are all terms that we talked about in our last lesson video. So it's going to be between one of these three answers. And so when we take a look at this image down below, what we need to notice is that there is a beaker and the beaker has an outside solution here. And then it has a cell, a red blood cell right here in the middle. And so this image is indicating that the outside solution is 10% Salyut and indicates that inside of the red blood cell it is 0.1% Salyut. And so what we need to realize is that 10% and 0.1% when we compare these two numbers, 10% is higher. It is a higher salt concentration and 0.1% salute is lower. And so recall from our last lesson video that I so tonic is a word that means equal solute concentrations. But because 10% saw you is higher than 0.1% Salyut, they're not equal to each other. 10% is not equal to 0.1%. So we know that we can eliminate answer option B isotonic Uh, it would be isotonic if they both had the exact same percentage of salute the same concentration of solitude. Uh, on. So what we need to realize here is that this problem is specifically asking us toe label the tennis ity of the outside solution. So we need to focus on the outside solution. The outside solution is 10% salute. It is higher solute concentration. And so recalled the word that means higher salt concentration is hyper tonic. Hyper tonic means higher solute concentration. And so that means that the outside solution, the one that we're trying to label here, is going to be hyper tonic with respect to the inside of the cell So the correct answer here is going to be answer Option C. And so this, of course, means that the inside of the red blood cell is going to be hypo tonic. So inside here, we can say it is Hypo Tonic. And the outside here, we could say, is hyper tonic. And so again, we're labeling the outside solution, so it will be hyper tonic. And option A is not gonna be correct for the outside solution. So option C hyper tonic is the correct answer for this example, and I'll see you guys in our next video.
Direction of Osmosis
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So now that we've introduced Tennis City in our last lesson video in this video, we're going to talk about how tennis ity effects the direction of osmosis. And so what we need to recall from our previous lesson videos is that biological membranes are semi permeable, which means that some things can get across the membrane, but other things cannot get across the membrane. And so if the salutes that air in a solution cannot diffuse across the membrane from areas of high concentration, two areas of low concentration, then osmosis is going to occur and recall. Osmosis is the diffusion of water across the membrane. And so here's what you guys need to know. Water will always move from Hypo Tonic solutions towards hyper tonic solutions, and so this is the direction of water movement from Hypo towards hyper tonic solutions. And so this is going to allow water to move towards the Mawr concentrated solution of saw you in order to dilute that solution, and it will continue to move towards that solution until it becomes isso tonic. And so essentially, the water is moving to help to try to create equal solute concentrations in both solutions now you might be thinking, Wait a second. Doesn't that go against the natural tendency of diffusion? Don't substances always defuse from high concentration toe low concentration? But here you're telling me that it's diffusing from low concentration to high concentration. So how does that make sense? Well, what's important to keep in mind is that Hypo Tonic and hyper Tonic our terms that refer to the saw Ute concentration. However, water is not the salute. Water is the sol vent. And so what's important to keep in mind is that water is still moving from areas of higher concentration of water towards lower concentrations of water. So let's take a look at this and a little bit more depth here to clear this up. Hypo Tonic Solutions. They do have lower solute concentrations like we described in our last lesson video. However Hypo Tonic Solutions, even though they have lower solute concentrations, they actually have higher water concentrations and hyper tonic solutions. They do have higher solute concentration, just like what we described in our last lesson video, however, hyper tonic solutions. Although they have higher solute concentrations, they have lower water concentrations. And so what's really important to realize here is that water is the solvent, whereas Saul Utes are not the solvent. And so these terms hypo and hyper are referring to the concentrations of Saul Ute. However, water is not the concentration of Saul you and water is still going to be moving from areas of higher concentration of water towards lower concentrations of water. So once again, let's take a look at our image down below to try to clear this up even further. And so notice what we have here. Down the middle is a biological membrane, which is semi permeable, meaning that some things can cross the membrane. But other things cannot cross the membrane. And so, in a scenario where the saw utes cannot cross the membrane, Um, although the salutes would love to defuse from higher concentration toe lower concentration across the membrane, they can't because they're being blocked. And so, in some scenarios, if the salutes cannot diffuse across the membrane instead of the salutes diffusing from high to low concentration because they can't what's going to happen is water is going to move instead and in areas that are Hypo tonic, yes, they have lower solute concentration because hype a tonic is referring to the lower solute concentration, but it turns out that they have actually have a higher water concentration. They have higher water and hyper tonic solutions. Yes, they have a higher solute concentration because remember, hyper tonic is referring to the solute concentration being hired. However, higher salt concentration means that it's going to have lower water concentration. And by the way, the brackets that you see here just mean the concentration of. And so when you see something in brackets like H 20 in brackets, it means concentration of water and solute in brackets means concentration of salute. And so remember what we said. What you need to know is right here. Water will always move from hypo towards hyper tonic solutions. And so, over here on the left, we have hype Bo over here on the right, we have hyper, so water is always going to flow in this direction, and so if you're able to remember water flows from hypo towards Hyper, then you'll be good on most of your osmosis questions. And so we'll be able to get some practice applying the concepts that we've learned here, but once again keep in mind. Water always flows from hypo towards hyper tonic solutions. So that being said, I'll see you all in our next video.
Osmosis is best defined as the movement of:
Water molecules across a semi-permeable membrane into a region of low solute concentration
Solute molecules from an area of high concentration to an area of lower concentration
Water molecules across a semi-permeable membrane into a region of high solute concentration
Water molecules inside a cell that can’t be transported out
Solute molecules from an area of low concentration to an area of higher concentration
Which direction would you expect water to move across the cell membrane?
Into the cell
Out of the cell
Into the cell and out of the cell at equal rates
Water will not move across the cell membrane
Environmental Tonicity Affects Cells
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So in our previous lesson videos, we introduce tennis ity and the direction of osmosis across a membrane. How water flows from Hypo Tonic solutions towards hyper tonic solutions. And so in this video, we're going to talk about how the environmental tennis ity effects cells, and so we're mainly going to be focusing on the outside environment that surrounds a cell. And so if the outside environment that surrounds a cell is hypo Tonic, then in this scenario water is going to enter the cells and cause the cells to swell up or enlarge like a hippo. And so you can think that Hypo Tonic environments cause cells to swell up or enlarge like ah hippo. Now, for animal cells that do not have a cell wall, they could potentially lice or burst under these conditions. And so you can think of it like a balloon If the cell is a balloon, if you blow too much air into a balloon, then it's going to expand in large or swell like ah hippo. But if you blow too much Erin into it, then it could potentially pop open. And so the same goes with cells cells, if too much water enters the cells, they could swell up too much, and if they swallowed too much, they could potentially lice or burst. And so, for animal cells that do not have cell walls, they do not prefer hype a tonic environments because they could potentially lice or burst, which could kill them. However, for plant cells that do have cell walls, the cell walls can prevent the expansion of the cell membrane. And so that means that the cell membrane is protected from licensing or bursting open with plant cell walls and so plant cell walls and plant cells. They actually prefer Hypo Tonic environments, and this is because they do not lice or burst open. And when the water enters the plant cells, it actually increases what is known as turker pressure and turker pressure is pretty much defined as the water pressure that's on the cell membrane, and this allows plants to have their upright and healthy structure. So let's take a look at our image down below to clear up some of these ideas, and we're gonna be focusing mainly on the left hand side of the image over here. And so once again, when the outside environment that is surrounding a cell is Hypo Tonic, then that could potentially cause a cell to swell up like a hippo. And so when we take a look here at this top part of the image, notice that we're showing you an animal cell and notice that it's a blood cell. And water is moving towards the inside of the cell in the hype, a tonic environment. And so notice that when water goes into the cell just like blowing air into a balloon, the cell is going to expand. But if it expands too much, it could potentially cause cell license, essentially causing the cell to burst open, killing the cell. And that's exactly what's happening right here with this animal cell and so animal cells, because they do not have cell walls, they could undergo sell license, and that could kill the cell. And so animal cells do not prefer hype. A tonic environments, however noticed down below. What we're showing is a plant in a plant cell, and plant cells have a cell wall that surrounds the cell membrane, and the cell wall prevents the expansion of the cell membrane, and so it prevents cell license And so plant cells do not have to worry about licensing in hype a tonic environments and instead plant cells. They actually prefer hype, a tonic environments, and the reason for that is because it leads to high turker pressure. Essentially, the cell membrane that is, uh, surrounding the cell here is applying pressure to the cell wall that surrounds the cell as well, and that allows the cell to the plant to take up a new, upright, healthy structure like what we see here and so once again, plants they prefer to be in Hypo Tonic environments, but animal cells, they do not like hype a tonic environments. So now let's take a look at the second type of environment. If the outside environment that is surrounding a cell is is a tonic, then in that scenario, water is going to both enter and exit the cell at equal rates. And that means that if water is going in and leaving the cell at equal rates, then the cell is not really going to change in size, and so this is actually preferred by animal cells like our blood cells. So let's take a look at our image down below here in the middle, where we're showing you the conditions where the outside environment surrounding the cell is isotonic. Uh, in this scenario, water is going to both enter cells, and water is going to leave cells at equal rates, which means that the cell is not going to change in size. And for animal cells like these red blood cells that we're showing you here, they actually prefer isotonic environments. Now, taking a look at the plant cell down below when it is in an isotonic environment, water. Once again we'll go into the cell and leave the cell at equal rates. And so the plant cell is not going to change in size. However, notice that the cell membrane here is not applying a lot of pressure to the cell wall. There are these gaps between the cell membrane and the cell wall, and so that means that there is not a really high amount of turker pressure and plants. They don't really prefer isotonic environments because it doesn't allow them to have the high turker pressure that allows them to have their upright, healthy formation. So now let's take a look at the final environment and if the outside environment that is surrounding a cell is hyper tonic and that scenario water is going to exit cells, and when water exit cells, it's almost like deflating a balloon. And so the balloon will get smaller and the cell would also get smaller and shrivel up and shrink down. And also because water is exiting, that's going to cause the cells to dehydrate. They're going to be losing water. And this is very similar to how AH hyper kid gets dehydrated. And so you can think, Hey ah, hyper kid that's jumping all up and down and never stops jumping around. They also get dehydrated, and so you can think hyper and hyper can lead to dehydration water leaving the south. So let's take a look at our image down below, over here on the right hand side, where the outside environment surrounding the cell is hyper tonic and that scenario, once again, water is going to be leaving the cell exiting the cell. And when it does that, the cell itself is going to shrivel up and shrink down and get dehydrated, just like all of these cells here so we can say that cells will be hydrate in this environment. And so this means that animal cells do not prefer hyper tonic environments because dehydration can lead to cell death now down below. Here with the plant cell were also showing the plant cell in a hyper tonic environment. And once again, water is going to be leaving the plant cell. In this scenario, and in this scenario, what you'll notice is that the cell membrane, which is right here, is not applying ah lot of pressure at all to the cell wall that surrounds it. And so there is a really low amount of turker pressure, and that will cause plants toe, lose their upright, healthy structure and begin toe wilt and die off is well. And so neither animal nor plant cells prefer hyper tonic environments because it will lead toa dehydration and low turker pressure for plants. And so, uh, what you can see here is that plant cells once again prefer Hypo tonic environments. Animal cells, uh, here prefer isotonic environments, and neither plant or animal cells prefer hyper tonic environments. And so this year concludes our lesson on how environmental tennis ity effects cells 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.
Plants become turgid when placed in this type of solution:
What would you expect to happen to the cell under the following conditions?