Bio 130: Unit 10. Cytoskeleton

What are microtubules?

- These are the largets kind of filament. - They have the ability to change their length, they can get bigger or smaller. - This is called dynamic instability, since they can change their shape. - they play a really big role in oraganizing roles in Eukayotic cells. - also anchor organelles in place. - They help position things in the cell, like the organelles. this helps the mitronchondria in the cell, along with the nucleus. - These help with reorgainzation the locations of different organlles,

What are the Intermediate filaments?

- They're like ropes, they extend from contracts on cells. They allow cells the ability to deal with stress which allows them to be elastic. so we can pull them apart without breaking. - These are seen as structural, they are not involved in cell movement. They basically prevent the cell from breaking by anchoring the cells. - these filaments do not dissassemble. They are up and they stay up. - Intermediate filaments redistributes the pressure applied, so like adding finer glass and metal. - These filaments allow the cell to have a stronger mechanical force and stops cell distortion. They have globular ends, these carry the moleucles that will determine the location of the filament.

What are the three types of cytoskeleton filaments?

1. (thinnest) Microfilaments. 2. (middle) Intermediate Filaments. 3. (largest) Microtubules

What is the cytoskeleton?

The cytoskeleton is a network of protein fibers that is within the cytoplasm. - It is important since it determines cell shape, position of organelles, and allows the movement of organelles within the cell. - provides support for the plasma membrane and nuclear membrane.

Do prokaryotics have a cytoskeleton? OR is it just Eukaroytes?

Both have cytoskeletons.

Compare the flagella motion in Eukarotic cells, and Prokaryotic cells

Eukaryotic cells: The motion of the flagella is like swimming, they are also covered by a membrane. In prokaroytic cells, the flagella is like the motion of a propeller. They are not covered by a membrane.

What are microtubuals made out of ?

Hollow Tubulin - There are 2 important things to know about tubulin. When they are stacked together, they create an asymetric polymer. It also only grows in one direction. - The microtubuals will grow as long as the adding of tubal subuniits is quicker than GTP is hydrolized. In the tubuals, we have an a at one end and a b at the other.

What are the two microtubual motor proteins?

Kinesins: These move them towards the plus end. Dyeins: Move them towards the minus end. - micortubuals can move in two directions, so we have these motor proteins to dictate where they go.

How do intermediate filaments affect the nuclear envelope?

The properties of the intermediate filaments, allow them to support the nuclear envelope in a numerous amount of ways. - During interphase, they anchor the chromomsomes, so the chromsomes are held right below the nuclear membrane. - they forma mesh like network.

What are Microfilaments?

These are a type of cytoskeleton filament. They are the smallest. - We can think of them as threads. - they are structured right below the plasma membrane. - They are also called actin filaments. - they have a plus and minus end. It's considered dynamic, so it ccan extend and contract. - tends to grow faster in the plus end than the minus end. - located below the plasma membrane - Basically the function for the actin filaments is to provide cell shape, and cell movement. - cool thing about actin is that it doesn't require an organizational center. They just polymerize anywhere they want. - these guys only have a single direction of tansport. And it's towards the plus end of the microtubual. - so this is considered unidirectional trasnport

What are Keratins?

These are the most diverse diverse class of intermedaite filaments. These are basically dead skin cells. - Dead cells will get filled with Keratin which will then bring the cells over to the cytoplasm.

Where do Microtubuals comes from?

They come from organizational centers. - we have stable microtubuals, and these are formed in a differeent type of orgainzational center. The basal body - they play an important roll in shaping the cell.