00:01
So we're going to take a look at some review questions here about diffusion, active transport, osmosis, facilitated diffusion, equilibrium, and see what we can come up with here.
00:11
We're going to start out with a cell, and in the cell is high co2, and outside the cell is low co2.
00:25
And in this case, we see the particles moving, the co2 particles moving from high concentration, to low concentration.
00:35
So we're going to be moving from the interior of the cell out.
00:40
Co2 is a small particle, and it is not impeded by the cell membrane.
00:46
So in this case, this is a case of true diffusion.
00:54
If we look at another cell, and we're looking at water, so we have two water molecules outside, and eight water molecules inside.
01:09
Here, since we're talking about water and moving through a membrane, this is going to be osmosis.
01:19
And we'll still see there will be channels in place, aquaporins, they're called, and water will move out of the cell, kind of like diffusion down a concentration gradient, but because we're looking at water molecules, we call that osmosis.
01:43
Here we have another cell with 25 glucose molecules inside and five glucose molecules outside.
01:56
And again, we're going to see that movement down a concentration gradient.
02:04
So glucose moves out, but glucose is a large molecule.
02:09
So what we're actually going to see is glucose needs help to get across the cell membrane.
02:17
So that's facilitated diffusion.
02:22
So the difference between diffusion and facilitated diffusion is the presence of a protein carrier.
02:29
Diffusion will happen without the carrier.
02:31
Facilitated diffusion needs that carrier.
02:35
Let's take a look at another cell, two sodium ions inside and eight.
02:45
Sodium ions outside...