Cytoskeleton Flashcards
What types of filament proteins are the cytoskeleton composed of?
Microtubules
Microfilaments
Intermediate filaments
What are the functions of the cytoskeleton?
Maintenance and changes of cell shape.
Movement and positioning of organelles, vesicles and molecules in the cytoplasm.
Movement of integral cell proteins of the PM.
Movement of cells.
Supporting cell - cell and cell - extracellular matrix interaction.
How can the cytoskeleton be visualized?
Using immunoflourescence against antibodies in the cytoskeleton.
Describe the shape and size of the filament proteins.
Microfilaments and microtubules are composed of globular proteins, while intermediate filaments are true filament shapes.
Microtubules can reach 10-12 μm in neurons.
Microfilaments and intermediate filaments can be from 35 μm in some microns.
Describe the positioning of the filament proteins.
Microfilaments are usually organized to the edge of the cell. This is how they provide and contribute to the shape.
Microtubules positioned close to the nucleus. From here they grow and reach the peripheral of the cell.
Intermediate filaments like to go from one side of the cell to opposite, important in determining resistance to stress forces.
What is a filament formed from?
A filament is formed by the polymerization of protein subunits (monomers) globular (microfilaments and microtubules) or filamentous (intermediate filaments).
Describe the different domains.
NH2 is where the GTP binding domain is.
In the middle of is the domain where drugs can bind.
COOH is where MAPs bind.
Which end of the microtubule is more stable?
The - end is more stable.
Describe the general structure of microtubules.
Alpha and beta tubulin monomers associate to form tubulin heterodimers, which then binds together to promote a hollow ring.
They stack on top of one another in a spiral form, the beta and alpha tubulin monomers stacked on top of one another associate in linear columns called protofilaments.
Describe what is meant by critical concentration.
The concentration at which assembly and disassembly are at equilibrium.
Describe the Trademilling Dynamic.
+ and - ends have different critical concentrations, particularly + end has a lower cc than - end.
If the concentration of free tubule is higher than the cc of + end and lower at the - end, the tubule monomers will be added at the + end and released at - end.
Therefore if we have labelled tubule, we will observe that this is added at the + end and seems to move towards the - end. This is because more unlabelled tubules will be added to the + end and the ones before the labelled tubule will be removed at the - end.
