00:06
So when we talk about cell transport, one of the things that we want to start with is the idea that there's two types of transport.
00:19
We have passive transport, and then we have active transport.
00:27
And let's talk a little bit about the difference between these two.
00:31
So passive transport, what we're looking at is we're moving molecules from high concentrations.
00:37
So these are my molecules.
00:38
And we see that there's a lot of them inside the cell and we're moving them to where there's a low concentration.
00:47
And we could do the opposite.
00:49
We could have the high concentration inside the cell and we could be moving it outside the cell.
00:58
So with passive transport, there's a couple things to note.
01:02
We do not use energy.
01:09
And again, we're always going from a high concentration to low concentration.
01:20
So the thing that's happening is we're actually using the concentration gradient to drive the movement of these molecules.
01:26
So we're actually using kinetic energy.
01:31
The types of molecules that we would move in this case would be small molecules, non -polar molecules.
01:45
In our example there, we could use oxygen, carbon dioxide, and some water.
01:56
Now, the reason we have non -polar molecules is because, again, we have these hydrophilic polar heads of our phospholipids facing outward.
02:07
When we go to active transport, this is with energy.
02:13
We have to use energy to move the molecules, and we're using atp as our primary force.
02:21
In this case, we can drive molecules against the concentration gradient.
02:32
So i often like to refer to it as going up the hill.
02:37
So we're going to go from low to high.
02:45
We also use active transport when we're moving large molecules.
02:55
We could use for bulk transport and to move our ions.
03:04
Okay.
03:05
So all of these would be included in active transport.
03:16
So again, just very quickly, again going from high concentration to low concentration.
03:31
Now let's look at some of our different, when we talk about passive transport, one of the things that i do want to look at is what's called facilitated diffusion.
03:51
So now when we talk about some of our passive transports, we have diffusion, which can be divided up into two things.
04:07
We have simple, which these are small molecules like carbon dioxide, oxygen, water.
04:20
But then we also have what's called facilitated diffusion.
04:32
And facilitated diffusion, just like diffusion.
04:35
We're moving molecules from high concentration to low concentration, but the difference is, is this one uses a helper protein.
04:50
And a good example of facilitated diffusion would be the movement of glucose across the membrane.
04:57
And we're going to again go with water.
05:00
And the reason we mentioned water is because, remember, water is a polar molecule, and our membrane that those phospholipids that are facing outwards are also polar.
05:11
So it's just a little easier to move larger amounts of water using facilitated diffusion.
05:18
So when we look at this, we actually have two different routes that we can go with this.
05:27
We can just use our channel protein.
05:32
And so when we look right here, we see the channel protein.
05:42
And we can see our molecules passing through the membrane.
05:46
Our other type of protein that we would use in facilitated diffusion is our transport proteins or carrier proteins.
05:57
Let's change that.
06:02
And with carrier proteins, we're actually going to, the molecule actually binds to the protein and alters its shape and then it's transported across.
06:17
So this is an excellent method for transporting glucose.
06:25
And again, you have to keep in mind that this is without energy...