In this video, we'll take a look at different types of membrane transport mechanisms. Now, here we're going to discuss how non-polar molecules, polar molecules, and ions move across the cell membranes differently. Because of this, we'll need different types of mechanisms.

The first one is simple diffusion. Here, this is the movement driven by concentration gradients. We're going to say that small, non-polar molecules and water are involved. Examples would be oxygen, CO₂, or steroids. If we take a look here, we're going to say this is the outside of the cell and this is the inside of the cell, we can see that these particles are just kind of going through the lipid bilayer, going from the outside, through the bilayer, and winding up on the inside of the cell. This represents simple diffusion.

Next, we have facilitated diffusion. This is gradient-driven and it's through a protein channel. Now, here we're going to discuss dealing with polar molecules and ions. Examples would be glucose, water, chloride ions, and bicarbonate. If we take a look here, we have our integral protein, which, remember, goes through the entire thickness of our lipid bilayer. We're going to say that these particles are going through the protein channel, which goes on both sides of the lipid bilayer. So they go through here, which is on the outside, and exit out here onto the inside. This would be facilitated diffusion, where we are using the protein channel to help move the particles from the outside to the inside of the cell.

Then finally, we have active transport. In this, we're going to say protein channels or pumps use energy to move substances against a concentration gradient. We're going to say this is highly selective and regulated, with different pumps for different substances. Some examples are our Sodium Potassium Pumps, which move sodium out and then potassium inside the cell. So, if we take a look here, energy is involved, and that's what makes this active transport. It's not just simply having an integral protein; we also have the inclusion of energy in order for our particles to go in and out of the cell.

Alright. Just remember, we have different types of membrane transport mechanisms, and they deal with the transporting of materials inside and out of the cell. This involves non-polar molecules, polar molecules, ions, and when it comes to active transport, the inclusion of energy.