Your body needs structure. Without it, we’re just a puddle of skin and blood. For the human body, this structure is provided in part by the skeleton. But our cells, the fundamental units from which we’re built, also require structure. Though we often think of cells as a jiggly bag of cytoplasm with little if any rigidity, this is quite untrue. This rigidity is provided by the cytoskeleton; a critical feature of the cell. Without it, cells cannot properly function.
Like most things in cells, the cytoskeleton is composed of proteins. There are three main types of cytoskeleton proteins: microtubules, intermediate filaments, or micro filaments. All three types are actually built of many smaller protein units that string together in a chain.
Microtubules are the largest of the three types. They are, as the name suggests, tubes. A major difference between this type of skeleton and our bones, is that the microtubules are dynamic. By this, I mean that they are constantly extending and shortening in length. This is done by adding and removing protein units from the ends of the chain. The microtubules play an incredibly important role in the cell. These are the tubes that connect to the chromosomes during mitosis. A dynfunction with the microtubules would disrupt proper chromosome sorting which could cause all kinds of problems with cell division. Also, in the nervous system, microtubules are what give the axon (the thin, wire-like structure that transmits signals) its shape. In fact, one of the major problems that arise in Alzheimer’s Disease is that a protein (called Tau) interferes with the microtubules and causes tangles to occur within the axon. This results in the devastating cognitive disruptions seem in individuals suffering from this disease. Additionally, microtubules can act like “train tracks”, allowing the cell to transport vesicles to specific locations within the cell.
The other two types of cytoskeleton proteins, intermediate filaments and microfilaments, have completely different roles than microtubules. They contribute to overall shape and strength of the cell. They stick to the cell membrane in a mesh-like fashion, giving it more strength. Additionally, they can act as an anchor point for membrane proteins, holding things in a fixed location in the membrane. This is very important for proteins, such as receptors, that do not need to move around in the membrane. Again, disruptions with either of these two types of proteins can result in all kinds of massive problems for the cell and the organism as a whole.
As you can see, cytoskeleton proteins are vital to life. Without it, cell function falls apart and the organism composed of the cell suffers terribly from the effects.
