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6. The Membrane

Simple and Facilitated Diffusion

6. The Membrane

Simple and Facilitated Diffusion

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1

concept

Simple and Facilitated Diffusion

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in this video, we're going to talk about simple and facilitated diffusion. And so both simple diffusion and facilitated diffusion are types of passive transport. Which recall means that the transport across the membrane is going to occur passively without any energy input whatsoever. And so there's absolutely no energy involved with passive transport. And that means there's no energy involved with either simple or facilitated diffusion. And also recall from our previous lesson videos that the reason passive transport requires no energy is because molecules are gonna be transported down their concentration. Grady INTs from areas of high concentration down to areas of low concentration. And that's why no energy is required Now. Simple diffusion, as its name implies, is pretty simple. And it involves the direct diffusion of small, uncharged molecules directly through the cell membrane, squeezing its way between the fossil lipids to get from one side of the membrane to the other side of the membrane down, its concentration radiant with no energy whatsoever. Now, facilitated diffusion, on the other hand, is going to be non energetic, diffusion, non energetic, meaning that no energy is involved because it's passive transport. And instead of diffusing small uncharged molecules typically facilitated diffusion is going to transport charged molecules. But as its name implies, facilitated diffusion is going to be facilitated by a transport protein. And so facilitated. Diffusion requires facilitation by a transport protein, whereas simple diffusion does not require any facilitation whatsoever. So let's take a look at our image down below to get a better understanding of this. So notice that over here on the left hand side, we're showing you a little snippet of our map here, where you can see that passive transport, which requires absolutely no energy input whatsoever, includes both simple diffusion and facilitated diffusion. And simple diffusion is pretty simple and straightforward requires no facilitation from a protein, so no protein is involved with simple diffusion, whereas with facilitated diffusion, the transportation does involve a transport protein, and the transport protein is what facilitates this diffusion. So let's take a look at our image over here to get a better understanding of this. So over here on this half of the image, we're showing you simple diffusion, which is going to allow small, uncharged molecules to simply defused directly through the membrane. And so these molecules here are uncharged, and they're small enough to be able to squeeze their way between the fossil lipids and get to the other side of the membrane from an area of high concentration down to an area of low concentration. And because it's going from high concentration, toe low concentration down the concentration radiant. That is why no energy is required for this type of transport. Simple diffusion. Now, over here on the right hand side of this image, notice that we're showing you facilitated diffusion and facilitated diffusion is also going to transport molecules down their concentration. Greedy INTs from an area of high concentration down to an area of low concentration, which is why no energy is required. Also know energy is needed for simple diffusion, and no energy is needed for facilitated diffusion. And really, the differences are that facilitated diffusion is mainly going to be transporting ions or, in other words, charged molecules, whereas simple diffusion will only occur with small, uncharged molecules, not with ions. If ions want to get to the other side of the membrane, then they're gonna need some facilitation by a transport protein. And so this protein that you see right here embedded in the membrane notices creating a channel basically a tunnel through the membrane that allows these ions thes charged molecules to defuse down their concentration. Grady INTs across the membrane, and so a protein is involved. But no energy is needed because the molecules move from high concentration toe low concentration. And so this year concludes our introduction to simple and facilitated diffusion, and we'll get to learn Maura Maura about these processes as we move forward in our course, so I'll see you in our next video.

2

Problem

Problem

Which of the following processes includes all of the others?

A

Osmosis

B

Facilitated diffusion

C

Passive transport

D

Transport of an ion down its electrochemical gradient

3

Problem

Problem

The difference between simple and facilitated diffusion is that facilitated diffusion:

A

Requires a protein transporter.

B

Moves molecules against their concentration gradient.

C

Requires energy.

D

Freely diffuses molecules against their concentration gradient.

4

concept

Transport Proteins of Facilitated Diffusion

4m

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So now that we know from our last lesson video that facilitated diffusion requires transport proteins in this video, we're going to talk about some of the transport proteins of facilitated diffusion. And really, there are two main types of transport proteins involved in facilitated diffusion, and we have those two number down below number one and number two. And so the first type of transport protein involved in facilitated diffusion are the poor ins otherwise known as channels. And so, as their name implies, porn's and channels, they're going to form an obvious, membrane spanning tunnel that will allow molecules to move across the membrane, Uh, by traveling through the tunnel that these parents or channels create. And so poor ins, uh, implies the word poor and poor is like a whole or like a tunnel, and channels once again are basically like tunnels as well. Now, aqua por ins are specifically used to transport water molecules across or through the cell membrane, essentially facilitating Oz moses so that as Moses, the diffusion of water across a semi permeable membrane can occur at a faster rate. Thanks to the aqua porn's now the second type of transport protein involved in facilitated diffusion are the transporters otherwise known as carriers. Now the transporters or carriers. Unlike the porn's and channels, they do not form an obvious membrane spanning tunnel. Instead, the transporters air carriers there, Onley open on one side of the membrane at a time, and they must undergo confirmation. All changes in order to move molecules across the membrane. So let's take a look at our image down below to get a better understanding of these ideas. So notice on the left hand side over here, what we're showing you are poor ins and channels. And so notice that porn's and channels they're going to create a membrane spanning tunnel that is basically going to allow molecules to move through the membrane through the tunnel and cross to the other side. Now, Aqua Porn's are specifically porn's that allow water molecules to diffuse across the membrane at faster rates, essentially allowing osmosis to occur faster. And you can see that channels like ion channels like this can allow ions that have charges like a positive charge, for example, to move through the tunnel here and get to the other side of the membrane. And so over here, what we see is that there are obvious membrane spanning tunnels, and so there's an opening on both sides of the membrane. Now, when we take a look at the right hand side of the image over here, notice that we're showing you transporters or carrier proteins. And so when you look at these, notice that it does not form an obvious membrane spanning tunnel like these do over here. Instead, the transporters are Onley open till one side of the membrane at a time. And so, in order to transport these molecules from one side of the membrane to the other side of the membrane, this transporter or carrier protein must undergo a confirmation. Allchin change. And so notice that over here the transporter carrier has undergone a confirmation. I'll change that can allow the molecule on the inside to be released to the other side of the membrane. And so what you'll notice is that here theme, the, um, transporter or carry your protein is only open till one side of the membrane, which is over here, and it's closed on this side of the membrane. And so transporters or carriers are Onley gonna be open toe one side of the membrane at a time. And it's on Lee after the confirmation of change occurs where they can change their shape and be open on the other side of the membrane. And so both of these are types of transport proteins involved in facilitated diffusion, allowing molecules to be transported down their concentration. Grady INTs passively, without any energy input. And so this here concludes our lesson on this, and 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.

5

Problem

Problem

Which of the following does not accurately describe a channel or a carrier?

A

Channel – open to both sides of the membrane simultaneously.

B

Carrier – open to one side of the membrane at a time.

C

Carrier – requires a conformation change to complete function.

D

Channel – not selective for molecules that move through it.

6

Problem

Problem

Which type(s) of molecules cannot enter/exit the cell via simple diffusion and require facilitated diffusion?

A

Nonpolar oxygen gas molecules.

B

Charged Ca²⁺ ions

C

Nonpolar carbon dioxide gas molecules.

D

Nonpolar water molecules

E

Charged Na⁺ ions

F

b and e only

G

a, c, and d only

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Additional resources for Simple and Facilitated Diffusion

PRACTICE PROBLEMS AND ACTIVITIES (6)