Cell Bio 4

cytoskeleton

network of protein fillaments that extend throught the cytoplasm

intermediate fillaments

provides great tensile strenght to the cell and nucleus

Microtubules

act as train tracks

provide support and internal framework to the cell

provide the roadwells and play a major role in cell division with mitosis (splitting the DNA)

also forms cilia and flagella

Actin filaments (microfilaments)

provides the plasma membrane with strength and shape

allows for cell movement

Main three components of the cytoskeleton

1. intermediate filaments

2. microtubules

3. actin filaments (microfilaments)

How are the three filaments made?

by the joining of small subunits noncovalently linked together

Protofilaments

are long string of subunits joined together end to end

nucleation

is the initiation process of assembling subunits - requires a aggregation step

Bonus: getting the subunits to attach to a string of small subunits is easy but the initial step of combining two small subunits together is the nucleation

is nucleation a part of the cytoskeleton

No as it is what begins the assembly of the subunits of the cytoskeleton

tubulin

the subunit that makes up microfilaments each tubulin subunit is composed of a dimer of a alpha and beta tubulin

• alpha giving the + end

• Beta giving it a - end