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Microfilaments and intermediate filaments

Video transcript

microfilaments are found in the cytoplasm and they are composed of a protein known as actin and many molecules of actin will join together to form an actin polymer and then the actin polymers will twist around each other to form an actin filament and microfilaments are mainly involved in the gross movement of the cell and microfilaments are dynamic and what we mean by that is that they can lengthen and shorten very frequently and in that sense they're similar to microtubules so they become longer in a process known as actin polymerization and they become shorter in a process known as actin depolymerization and it's the polymerization and depolymerization that helps to move the cell so one example of where microfilaments help with the gross movement of a cell is during cell division so the cell at some point is going to be pinched in that way and then eventually it will separate into two separate cells and the microfilaments help the cell make that kind of pinched shape and then move to create two separate cells another example of where microfilaments help with the movement of a cell is in an amoeba so let's say here's our muta cell and we're going to say that it's trying to capture this piece of food right over here so in order for it to do that it has to extend its pseudopods in that direction and move around that food molecule and what helps those pseudopods move the microfilaments let's move on to intermediate filaments so intermediate filaments in contrast to microtubules and microfilaments are made up of many different types of proteins that are strung together into polymers and then these polymers twist together to make the intermediate filaments and intermediate filaments are different than microtubules and microfilaments in that they're pretty much permanent so once they're made by the cell they kind of stay put as opposed to microtubules just never be like Brie v8 like that and microfilaments that we explained our dynamic they constantly change depending on the needs of the cell so what do intermediate filaments do well they provide structural support for the cell or another way to say this is they resist mechanical stress and in the picture it almost looks like the intermediate filaments are this supporting wire and if you recall in our introduction to cytoskeleton we mentioned that the intermediate filaments can be compared to the springs inside of a mattress so if you were to sit down on a mattress you might squish it a little bit but once you stand up the mattress will revert to its original ship shape thanks to the springs inside so the intermediate filaments in blue in this picture act in the same way