Active Transport - Video Tutorials & Practice Problems
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1
concept
Active Transport
Video duration:
2m
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Video transcript
In this video we're going to begin our lesson on active transport. And really there are just 2 main types of active transport that you all should know that both require energy in order to transport molecules. This is because the molecules are going to be transported against their concentration gradients from areas of low concentration to areas of high concentration and that's why it requires energy. Now, the first type of active transport that you all should know is Primary Active Transport. And so Primary Active Transport is going to be directly driven by an energy source such as ATP hydrolysis for instance. And so primary active transport is directly linked to ATP. Now the second type of active transport that you all should know is secondary active transport. And secondary active transport is not going to be directly driven by ATP hydrolysis like primary active transport, instead secondary active transport is going to be directly driven by another molecule's concentration gradient. And so as we move forward in our course we'll be able to talk more details about both primary active transport and secondary active transport. But let's take a look at our image down below, which notice is showing us a little snippet of the map of the lesson on membrane transport. So here we're showing you active transport, and notice active transport is going to require energy, so energy is required. And once again there are 2 main types of active transport. The first is primary active transport, which is going to be driven directly by ATP, And then the second type of active transport is secondary active transport, which is not driven directly by ATP, instead secondary active transport is going to be driven by another molecule's concentration gradient. And so here what we're showing you is an image of 1 molecule being powering, the transport of another molecule against its concentration gradient. Talk more details about primary active transport and secondary active transport. So I'll see you guys in our next videos.
2
concept
Primary Active Transport
Video duration:
2m
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Video transcript
So now that we know from our last lesson video that there are 2 types of active transport, primary active transport and secondary active transport. In this video, we're going to focus on primary active transport. And so primary active transport is an ATP driven process that transports molecules against their concentration gradients from areas of low concentration to areas of high concentration, and that is why it requires energy in the form of ATP. Now once again, primary active transport transport is going to be driven directly by energy derived from ATP hydrolysis. And really, this is the biggest difference between primary and secondary active transport. Primary active transport is directly linked to ATP hydrolysis, but secondary active transport is not as we'll learn, moving forward talking about secondary active transport in another video. Now primary active transport can be used to generate and maintain very very important concentration gradients for survival. And so we'll be able to talk about a very very important primary active transport example in our next lesson video. But for now let's take a look at the image that we have down below which is showing us Primary Active Transport. And so notice here we have a membrane, here in the middle, and notice that Primary Active Transport is going to require the use of a membrane protein, and that membrane protein is going to use ATP directly, as we indicated up above, in order to transport molecules against their concentration gradient from an area of low concentration over here on this side of the membrane because there are only 3 molecules, and it's still pumping them towards an area of higher concentration, and so you can see there is a much higher concentration over here. And so because this purple molecule is being pumped against its concentration gradient, it requires active transport. And because ATP is used directly, it is a form of primary active transport. And so ATP here is really providing the energy that is required to pump the molecule across the membrane. And so this here concludes our introduction to primary active transport, and we'll be able to see a very specific example of primary active transport in our next lesson video when we talk about the sodium potassium pump. So I'll see you guys in that video.
3
example
Active Transport Example 1
Video duration:
3m
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Video transcript
Alright. So here we have an example problem that's asking what is the main difference between active transport and facilitated diffusion? And we've got these 4 potential answer options down below. And so what we need to recall is that facilitated diffusion is not a type of active transport. Facilitated diffusion is a type of passive transport which means that absolutely no energy is required for facilitated diffusion and this is because molecules will be transported down their concentration gradients from an area of high concentration to an area of low concentration. And so when we take a look at option a here, notice it says facilitated diffusion uses proteins but active transport does not. And this is actually a false option, so we can cross it off our list. Now this is because both facilitated diffusion and active transport use proteins. And so, the facilitated diffusion require is, recall, is facilitated by a protein. And active transport also requires a protein as well. So both facilitated and active transport require proteins and that is not the main difference between them. Now skipping over b really quick, going to option c, notice it says active transport occurs across the plasma membrane but facilitated diffusion does not, and once again this is not going to be true. Of course, active transport and facilitated diffusion are both going to allow for molecules to be transported across a plasma membrane and so they both allow for that. So that is not the main difference between the 2. And then taking a look at option d here, it says active transport and facilitated diffusion both use proteins to move substances against their concentration gradients. Now we already indicated that active transport and facilitated diffusion both use proteins. That part is true. But they don't both, move substances against their concentration gradients. Only active transport moves substances against their concentration gradients from areas of low concentration to areas of high concentration. But facilitated diffusion, which again is a type of passive transport, it does not pump molecules against their concentration gradients, it pumps molecules down their concentration gradients. So that means that option d here is also not going to be true And this only leaves option b here as the correct answer, which says active transport uses ATP to power transport, but facilitated diffusion does not. And so we know from our last lesson video that more specifically, it's primary active transport that uses ATP directly to power transport. And facilitated diffusion, which is once again a type of passive transport, does not require any energy. So it certainly does not use ATP to power transport. And so option b here is going to be the correct answer for this example problem, and And that concludes this example, so I'll see you all in our next video.
4
Problem
Problem
The force driving simple diffusion is ________, while the energy source for active transport is ________.
A
a concentration gradient; ADP
B
a concentration gradient; ATP hydrolysis
C
transmembrane pumps; an electrochemical gradient
D
phosphorylated carrier proteins; ATP
5
concept
Primary Active Transport: Na+/K+ Pump
Video duration:
6m
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Video transcript
In this video, we're going to talk about a classic example of primary active transport in the sodium potassium pump. And so once again, the sodium potassium pump is a classic example of primary active transport. And as its name implies, the sodium potassium pump is going to pump or move sodium and potassium ions across the plasma membrane. But more specifically, the sodium potassium pump is going to move the sodium and potassium ions in opposite directions across the plasma membrane, which means that the sodium potassium pump is an anti porter, which recall from our previous lesson videos just means that some molecules will be pumped across the membrane towards the outside of the cell whereas other molecules are going to be pumped across the membrane to the inside of the cell in opposite directions. And so that is what makes this an anti porter. Now it turns out that 3 sodium ions are going to be exported towards the outside of the cell, whereas 2 Potassium ions are going to be imported towards the inside of the cell. And so what can help you remember that it's 3 sodium ions that are being exported is that the sodium here has 3 characters to it. It has the n, it has the a, and it has the plus. And so this, because it has 3 characters can remind you that it's actually 3 sodium ions that are gonna be exported towards the outside of the cell. And the Potassium symbol here has only 2 characters. So it has the k and it has the plus. And so that can help remind you that it's 2 Potassium ions that are being imported towards the inside of the cell. Now what can also help you remember that, potassium are going to be imported towards the inside of the cell is to just think of a pumpkin. Because if you think about a pumpkin, it'll tell you that the sodium potassium pump is going to pump k+ into the cell. And so if you remember pumpkin, you'll remember that, hey, potassium ions get pumped into the cell or imported into the cell. So let's take a look at our image down below to clear up some of this, and notice that right here in the middle, embedded in this plasma membrane that we see right here, is the sodium potassium pump right here. And notice that the sodium potassium pump is going to take 3 sodium ions and those 3 sodium ions are going to be exported towards the outside of the cell. So notice the outside of cell is up above on this side of the membrane, whereas the inside of the cell is down below. So 3 sodium ions are going to be pumped or exported towards the outside of the cell, and if that continuously happens over and over and over again, then there's gonna be a low concentration of sodium on the inside of the cell. So, remember the brackets here represent the concentration of so we have the concentration of sodium ions on the inside of the cell. It's gonna be really really low if it keeps pumping them towards the outside. And, of course, that means that on the outside, over time, there's gonna be quite a high concentration of sodium ions on the outside of the cell. And as the sodium ions get pumped, of course, we know that potassium ions are also going to be pumped, but it's actually just 2 potassium ions that are gonna be imported, and so the 2 potassium ions get imported towards the inside of the cell and that means that on the outside of the cell, if the potassium ions keep getting pumped in, there's gonna be a low concentration of potassium ions on the outside of the cell. And on the inside of the cell over time, it's gonna build up and there's gonna be quite a high concentration of potassium ions on the inside of the cell. And notice that with each, pump here, 3 sodiums out and 2 potassiums in, that ATP hydrolysis is required, And the ATP here is really what's providing the energy to pump these molecules against their concentration gradients from areas of low concentration towards areas of high concentration in both scenarios. So from areas of low concentration towards areas of high concentration. That requires energy and this is primary active transport because ATP is directly linked. Now over here on this right side of the image, we just have another way to help you remember that, hey. The sodium ions, they get pumped to the outside of the cell, and the potassium ions, they get pumped to the inside of the cell. And so you can think that the cell here is like a club. It's club intracellular and so you can see that the nucleus here is, like the disco DJ of the club. And, you could even think that these strobe lights here are kinda like the the exoskeleton, the, the cytoskeleton of the cell. And so notice that the sodium potassium pump is really gonna act like these bouncers to the club. And so you can see that the sodium ions, when they try to enter the cell, they say, bra, can we enter into the club and the sodium potassium pump because they're sodium and they're NA? The sodium potassium pump says, nah. You can't enter. You cannot enter. And so that can help you remember that, hey, the sodium are not going to enter the cell. They're going to get pumped towards the outside of the cell. However, when the potassium try to get into the club, they say, well, hey, we're back. Let us in. And, the sodium potassium pump, because, sodium is made up with a k, they just say, k, come on in. And so sodium is able to get into the club real easy. And so that can help remind you that, hey, sodium, I'm sorry, potassium is gonna be able to get into the cell because the sodium potassium pump says k, come on in. And the, sodium over here will not be able to get into the cell because when they try to enter, the sodium potassium pump says nah. And so, this here concludes our introduction to the sodium potassium pump and how it is a classic example of primary active transport. And we'll be able to get some practice applying these concepts as we move forward throughout our course. So I'll see you all in our next video.
6
Problem
Problem
A sodium-potassium pump ________.
A
Transports 3 potassium ions out of a cell and 2 sodium ions into a cell and produces a molecule of ATP.
B
Transports 3 sodium ions out of a cell and 2 potassium ions into a cell using energy from ATP hydrolysis.
C
Transports 3 potassium ions out of a cell and 2 sodium ions into a cell using energy from ATP hydrolysis.
D
Transports 3 sodium ions out of a cell and 2 potassium ions into a cell and generates an ATP in each cycle.
7
Problem
Problem
Which of the following defines the type of transport by the sodium-potassium pump?
A
Active transport through a symporter.
B
Passive transport through a symporter.
C
Active transport through an antiporter.
D
Passive transport through an antiporter.
8
concept
Secondary Active Transport
Video duration:
7m
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Video transcript
So now that we've covered primary active transport, in this video we're going to focus on secondary active transport. And so recall from our previous lesson videos that secondary active transport is not directly driven by ATP hydrolysis. That is primary active transport. Instead, secondary active transport is going to be directly driven by another molecule's concentration gradient. And it's going to be powered by another molecule's concentration gradient instead of being powered by ATP hydrolysis like primary active transport is. However, that being said, secondary active transport, although it may not be directly driven by ATP hydrolysis, it is indirectly driven by primary active transport and ATP hydrolysis. And the reason for this is because the concentration gradient that directly drives secondary active transport is actually built using primary active transport or PAT, which we've abbreviated, here for our lesson. And so, in order to better understand secondary active transport, we're actually going to take a look at a classic example in the sodium glucose secondary active transporter. And so down below, we have an image of this sodium glucose, transporter, and notice that the image has these numbers, 1, 2, 3, and 4, and these numbers that you see down below in the image correspond with the numbers that we have up above here in the text. And so this is really showing you the 4 steps that there are for this sodium glucose secondary active transport example. And so in the very first step here, what you'll notice is that sodium ions can be transported against their concentration gradient using primary active transport. And so when you take a look at our image down below, notice that the sodium ion, which we're showing you down below here in step number 1, is being pumped across the membrane in this direction, and it is being pumped towards the area of higher sodium concentration, whereas down below, there's a lower sodium concentration inside the cell. And so because sodium is being pumped against its concentration gradient from low to high concentration, it's going to require energy. And notice that ATP is directly linked to this process of pumping sodium across the membrane. And because ATP is directly linked here, it is a form of primary active transport just like what we mentioned up above. Sodium being transported against its concentration gradient using primary active transport. But we've already covered primary active transport, so really this is not, anything new to us. And so essentially in number 2, what this is going to generate is a higher concentration of sodium ions, generated on the outside of the cell. So the outside of the cell here has a higher concentration of sodium. You can see there are way more sodium ions, much a much much higher concentration than there are inside the cell, so there's a lower sodium ion concentration inside. And this is because, again, this primary active transport generates this, concentration gradient of sodium. But then what we need to also realize is in this image in number 3, there's another molecule that's also involved here, glucose, which we have in green. And so notice down below we have glucose as well. We have, these green hexagons here and also down below here. And notice that the glucose molecules, they actually have a higher concentration on the inside of the cell, which is opposite to that of the sodium. The sodium has a higher concentration on the outside of the cell. The glucose has a higher concentration on the inside of the cell. And so this is really where secondary active transport comes into play because sodium, is going to be transported down its concentration gradient from an area of high concentration to an area of low concentration, and that does not require any energy. In fact, it actually can provide and release energy. And so as the sodium gets transported down its concentration gradient, it's actually going to provide the energy. It's going to power the transportation of glucose against its concentration gradient. From the area of low concentration of glucose towards the area of high concentration of glucose. So once again, to better understand this let's take a look at this example over here. And what you'll notice is that sodium is going to be transported down its concentration gradient from an area of high concentration down towards an area of low concentration. And that does not require any energy for molecules to move down their concentration gradients. Instead, it's going to release energy, and that released energy can be used to power the movement of glucose against its concentration gradient from an area of low glucose concentration on the outside of the cell towards an area of much higher glucose concentration on the inside of the cell. And this is really, a type of active transport since molecule is being transported against its concentration gradient. But notice that no ATP is directly involved. Notice there's no ATP in this vicinity at all. And so because it's not driven directly by ATP, it's going to be driven by the concentration gradient of, sodium being transported down its concentration gradient. And so that makes this a classic example of secondary active transport. And so once again, as we mentioned up above with secondary active transport, it's gonna be driven, by the concentration gradient of another molecule instead of ATP hydrolysis. So over here with secondary active transport, notice that there's no ATP at all in this vicinity. And really it's just this concentration gradient of sodium going down its concentration that powers the secondary active transport here of, glucose being transported against its concentration gradient. And so this here concludes our introduction to secondary active transport, and we'll 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.
9
Problem
Problem
How are primary and secondary active transport related?
A
They both use ATP to move molecules
B
Primary active transport establishes a concentration gradient, but secondary active transport doesn't
C
Secondary active transport uses the concentration gradient established by primary active transport
D
Primary active transport moves one molecule, but secondary active transport moves two
E
None of the above
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