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15. Cytoskeleton and Cell Movement

Intermediate Filaments

15. Cytoskeleton and Cell Movement

Intermediate Filaments

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Intermediate Filaments

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Hi this video, we're gonna be talking about intermediate filaments. So intermediate filaments, their cellular components um that were to provide the cell with great strength, specifically tensile strength. So this just makes this the cell really strong and durable. And so because they make the cell durable, they also have to be the most durable side of skeletal filaments. So they allow the cell to withstand mechanical stress and things like pulling or pushing or you know, just twisting those types of movements. Intermediate filaments are great at and that's what they do and they allow the cell to withstand those movements versus just having to sell like completely collapse, break apart. And so the reason that they have this movement is because intermediate filaments actually form these long strands that are wrapped together kind of like a rope. A rope can with very easily handle being pulled by people. It doesn't rip in half or can be pushed together or it can be twisted and it doesn't break the rope. And intermediate filaments are exactly the same. They can be pulled push twisted but it's not going to break them. And it's because of them, it's not going to break the cell. And so intermediate filaments work because they're anchored to the plasma membrane and the nucleus. So that's important. So they're anchored to various portions in the cell. And it's kind of like a rope attaching the nucleus to the plasma membrane and that's allowed to be allowed to float, push pull against each other. But because they have these intermediate development ropes, they don't break apart. So intermediate filaments are formed by individual subunits that link together to form one filament which makes sense. Then there are two filaments. They form die MERS by binding a specific domain, a specific domain called the alpha helical domain on each of the sub units. So now the sub units are the, well the sub units are the small things that link together and each one of them have an alpha helical domain. And so when they form these filaments, they have a bunch of alpha helical domains which allow the filaments to form die MERS. And then two sets of diners come in and arrange themselves in opposite directions called anti parallel and they form te trimmer. So first you start out with these small subunits to form one filament. Then there are two filaments that form dimmers and then to die MERS work together to form these te tremors. But importantly important to know here and you probably don't know why, but I'm going to tell you why later in later videos is that they are unique because both ends are the same and I'll show you a picture of what that exactly means. But this is very unique inside of skeleton. Usually everything else. The ends are not the same. So the fact that intermediate filament ends are the same is a unique feature. And intermediate filaments are super important if they're mutated or something's wrong with them. They cause severe diseases. Things like Ls remember the ice bucket challenge? That's LS progeria is kind of advanced aging. They have TLC shows about it. But yeah so that is intermediate filament. So this is what they look like. So here you have a monomer and this is made up of a bunch of sub units. So we'll just say the sub units are here, they're much smaller than that in real life but it doesn't really matter. So you have this monomer. This form two of those transform a dime er that are wrapped around each other and then to die. MERS form a te trimmer. And what you'll see here is that the ends of all of these are exactly the same, which I said was important. So um now there are four classes of intermediate filaments. The first let me back out. So you can actually see this. Um The first is keratin and this is going to be in things like epithelial cells. So that skin cells you have the special class of the mitten or women and related. And these are going to be found in the nucleus into the cell periphery. You have neuro filaments which are exactly where you think they are. They're going to be in the neuron and then you have nuclear, oh you know across out nuclear Lammens and they support the nucleus. Um So those are your four class is important to know those four classes of intermediate filaments. Just because we're not going to go over really. Anything else to do with intermediate filaments. So it's a small amount to know about intermediate filaments, so you should probably know it. So let's move on.

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Problem

Problem

Which of the following is not a class of intermediate filaments?

A

Nuclear lamins

B

Neurofilaments

C

Vimentin

D

Integrins

3

Problem

Problem

Two intermediate filament dimers are arranged in which of the following ways to create a tetramer?

A

Parallel

B

Anti-parallel

C

End-to-End