Bio Sci 104
Without a cytoskeleton, everything would be spherical (energy minimization) and
cells would not be able to connect with one another to form tissues. Furthermore,
the subcellular organelles would float around in the interior randomly, vesicular
transport would be impaired, the complex process of replication, that involves
segregation of chromosomes and the physical division of the daughter cells, would
be impossible, and your skin would rip apart from the simple stress of rubbing
against your clothing.
A. The cytoskeleton is responsible for the overall shape, structure,
and movement of the cell
The cytoskeleton controls the shape of a wide variety of different cell
types. For example, the axon of a single neuron can be over a meter long, the
cytoskeleton makes this possible. It is also responsible for providing mechanical
forces such as those in muscle contraction.
The cytoskeleton also makes up your
skin, hair and nails. And it allows cells such as white blood cells to crawl. One last
example, the cytoskeleton creates the flagellum needed for sperm movement, and
cilia in your lungs.
B. The cytoskeleton is responsible for internal organization of the cell
This includes mechanical support of membranes, formation of microvili in your gut
that increases the surface area of a cell, or the hair cells of your ear. Without the
cytoskeleton, the secretory pathway would fail. The cytoskeleton moves vesicles from ER to
Golgi to plasma membrane, and positions the organelles of a cell.
The cytoskeleton is also essential for chromosome segregation in mitosis and cytokenesis to
complete cell division.
Cytoskeleton forms a highly dynamic structure that reorganizes continually as cell changes
shape, divides, and responds to environment.
C. Three classes of filaments
) -intracellular transport, mitosis
Actin Filaments (AF)
-determine a cell’s shape, locomotion, cytokenesis
Intermediate Filaments (IF)
-Provide mechanical strength and resistance to shear
Many other proteins bind to these cytoskeletal filaments to regulate their organization, to
link cytoskeleton to other elements of the cell, or to act as motor proteins. These accessory
proteins play important roles in controlling assembly and three-dimensional structure of the
different cytoskeletal filaments.
Intrinsic biochemical properties of filaments
1. The cytoskeleton is highly dynamic and adaptable.
-It is more like an ant trail than a permanent paved highway, constantly adapting to