Passive vs. Active Transport - Video Tutorials & Practice Problems
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Passive vs. Active Transport
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Video transcript
Alright. So in this video, we're going to distinguish between passive and active transport, which is something that you guys have done before in your previous biology courses. So again, nothing really new here and this should be a piece of cake for you guys. And we're also going to start to explore our membrane transport map. So we know that we're going to explore this map by exploring the left most branches first. So we're gonna start with molecular transport of very small molecules, and you can see in this map here that molecular transport of small molecules can be categorized into 2 different groups. The passive transport group and the active transport group. And again that's the main focus of this video that there are 2 general types of processes that transport molecules across biological membranes. The passive transport and the active transport. Now, over here on the left hand side, what we're showing you is passive transport, which again you might recall from your previous biology courses just means that there's going to be absolutely no energy input, And so passive, moving forward in our lesson, the word passive is going to mean that there is no energy input, and that's exactly what happens in passive transport. And so if there's no energy input what this means is that molecules are going to be diffusing across the membrane as so from areas of high concentration down to areas of low concentration, just like what you see over here in this image. Now over here on the right hand image, what you'll notice is we've got active transport, and with active transport you can see that, the active is going to represent that there is a need for energy. And so moving forward in our lesson, active is going to be, be symbolic of the requirement of energy. And so in this process, what you'll see is that usually, ATP is the molecule that provides the energy for active transport, and in active transport, instead of molecules diffusing from high to low concentration, they actually diffuse from low to high concentration, and that's exactly what we see here with these purple molecules. They're diffusing from low concentration towards the higher concentration, which is against their natural tendency, and that's why it requires energy. Now here in our, center table, notice we have a table with, all of these different columns here and, all of these different rows here, I should say, and, we've got these two columns, this one and this one, and again, the blue is going to represent passive transport and the yellow is going to represent active transport. And so in terms of an energy input, of course, as we've already mentioned with passive transport, there's absolutely no energy input, simple as that. And with active transport, of course, there is going to be an energy input, so we can put yes, and usually that energy is coming from ATP, as you'll see when we move forward and discuss active transport in more detail. Now in terms of the movement of the molecules relative to their gradient, in passive transport, as we already discussed, molecules are traveling down or with their concentration gradients, from areas of high concentration down to areas of low concentration. Whereas with active transport over here, of course, they're going to be traveling up their gradient or against their gradient from areas of low concentration to areas of high concentration, again, as we already indicated. Now, in terms of being thermodynamically favorable, because passive transport requires no energy, that means that it is indeed thermodynamically favorable. And, of course, if it's thermodynamically favorable in terms of being spontaneous, it means that it will be spontaneous, and it will be exergonic process. An exergonic processes we know have a negative delta g or a negative change in Gibbs free energy, and this will be relevant later in our course when we're talking about how to calculate the thermodynamic favorability of membrane transport later in our course. But in terms of active transport, on the other hand, thermodynamically favorable, we can say that it is not thermodynamically favorable. So, no, it is not thermodynamically favorable. And that means, of course, that it will not be spontaneous, and instead of being exergonic, it will actually be endergonic, meaning that it will have a positive delta g or a positive change in Gibbs Free Energy. Now in terms of protein facilitation, whether or not a protein is required for passive transport, the answer to that is sometimes. Sometimes a protein is required for passive transport to occur, and other times a protein is not required for passive transport. Whereas with, active transport on the other hand, protein facilitation is always required. And so you'll be able to see over here that there is a protein here embedded in the membrane that allows for active transport to occur. And so really what you can think of this, these 2 different groups of transport, passive versus active, is that passive transport over here does not require energy. So it's almost like downhill movement traveling from areas of high concentration down to areas of low concentration. So because no energy is required notice that this guy is just watching passively as the ball travels down the hill. Whereas with active transport over here notice that the transport is going to be from low concentration to high concentrations, and that is going to require energy. So you can see the guy here has to push the molecule into the area of high concentration, and that requires energy usually in the form of ATP. Now as we move forward in our course, we're going to break down passive transport even more, and later we'll break down active transport even more. So hang on tight. Let's practice the concepts that we've learned here in our next video. So I'll see you guys there.
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Problem
Problem
Passive membrane transport processes include___________.
A
Consumption of ATP for energy.
B
The use of transport proteins to move a substance from low to high concentration.
C
Movement of a substance down its concentration gradient.
D
Movement of a substance up its concentration gradient.
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Problem
Problem
What is the difference between active and passive transport across a plasma membrane?
A
Active transport is used to move substances down their concentration gradient, where passive transport is used to move substances against their concentration gradient.
B
Active transport is ATP dependent, whereas passive transport does not require energy for movement across the plasma membrane.
C
Active transport implies that the cell is working with other cells, whereas passive transport implies that the cell does not cooperate with other cells.
D
Active transport means that the cell is aggressively going after substances that it wants to bring into the cell, whereas passive transport means that the cell just waits for the substance to cross the membrane.
4
concept
Passive vs. Active Transport
Video duration:
3m
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Video transcript
In this video we're going to introduce the classes of passive and active membrane proteins. And so really there are 3 types of passive and active membrane proteins that are classified according to how they operate. And so the very first type here is going to be the uniporter, and so uni is a prefix that means one. And so these membrane transport proteins will only transport just one molecule at a time as its name indicates, and it will transport 1 molecule at a time in just one direction. So pretty simple. So if you take a look down below down at, the image what you'll see is that number 1 is our uniporter, and as you can see it will transport just 1 molecule at a time in one specific direction. Now the second type of membrane protein that we have here is going to be the symporter, and so symporters are going to co transport at least 2 molecules, so more than 1 molecule, at a time in the same exact direction. And so you could think that the s in symport is for the s in the same direction. And so when you take a look down below at our image at the symporter here, what you'll notice is it is indeed taking 2 molecules, either 2 of the same molecules or 2 different molecules, doesn't matter. Here we're showing 2 different molecules, and it's taking these 2 molecules and transporting them in the same exact direction, in this direction here. And in our last type of transporter, number 3 here, what we have is the Antiporter, and as its name implies it's going to co transport at least 2 molecules just like the symporter, but this time it's not transporting them in the same direction. This time it's transporting them in opposite directions. And so if we take a look down below at our image here of, number 3, the antiporter, notice that it is indeed transporting 2 molecules, the red one here and the green one down here. But again, notice this time they're not being transported in the same direction, they're actually being transported specific examples of each of these 3 different types of membrane transport proteins. And so that concludes our introduction to the classes of passive and active membrane transport proteins, and I'll see you guys in our next video.
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Problem
Problem
A transport protein that simultaneously transports two different molecules in different directions is called:
A
A uniporter.
B
A symporter.
C
An equilibrium protein.
D
An antiporter.
E
A simple diffuser.
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Problem
Problem
Which option below best describes a transporter that requires ATP to move molecules A and B out of the cell?