• What is cytoskeleton?
• Structure of cytoskeleton
• Function of cytoskeleton
• Intermediate filaments
What is cytoskeleton
• The complex network of protein fibers that give mechanical
support and strength to cell and maintain its
shape(especislly in animal cell) known as Cytoskeleton.
• Act as skeleton and muscle of the cell.
• Also responsible for segregation of chromosomes into two
daughter cell at cell division.
Structure of cytoskeleton
In eukaryotes, the cytoskeleton
is built on a framework of three
types of protein filaments.
And these are capable of rapid
growth or disassembly
dependent on the cell’s
FUNCTIONS OF CYTOSKELETON
• It imparts the cell shape.
• It provides protection by resistance to deformation.
• It can actively contract, deforming the cell and its environment,
allowing cells to migrate.
• It is involved in cell signaling pathways.
• It separates chromosomes during cell division.
• It provides a blueprint to organize the organelles in cytoplasm
and for the construction of cytoplasm.
• It gives rise to structures such as flagella and cilia.
• Microtubules are hollow rods functioning
primarily to help support and shape the cell
and as "routes" along which organelles can
• Microtubules are typically found in all
• They vary in length and measure about 25
nm in diameter.
• They are polymers of alpha and
• They have a very dynamic behaviour,
binding for polymerization.
• They are commonly organized by the
Functions of Microtubules
•Intracellular transport (associated
with dyneins and kinesins, they
transport organelles like mitochond
ria or vesicles).
•The axoneme of cilia and flagella.
•The mitotic spindle.
•Synthesis of the cell wall in plants
•Microfilaments or actin filaments are thin, solid
rods that are active in muscle contraction.
•Microfilaments are particularly prevalent in
•Microfilaments measure up to 8 nm in diameter.
• Major component or protein of microfilaments
•It consists of tropomyosin ,actin and troponin.
•Specifically,the actin subunits that come together
to form a microfilament called G-actin and once
they are joined called F-actin.
Functions of microfilaments
•Maintenance of cell shape
•Cytoplasmic streaming or cyclosis
•Intermediate filaments can be abundant in many cells and provide
support for microfilaments and microtubules by holding them in
• These filaments form keratins found in epithelial cells
and neurofilaments in neurons.
•They measure 10 nm in diameter.
•Intermediate filaments are most commonly known as the support
system or “scaffolding” for the cell and nucleus while also playing a
role in some cell functions.
Functions of intermediate filaments
Different intermediate filaments are:
•Made of vimentin. Vimentin intermediate filaments are in general
present in mesenchymal cells.
•Made of keratin. Keratin is present in general in epithelial cells.
•Neurofilaments of neural cells.
•Made of lamin, giving structural support to the nuclear envelope.
•Made of desmin, play an important role in structural and
mechanical support of muscle cells.
Cytoskeleton type Diameter
Microfilaments 6 Double helix Actin
Intermediate filaments 10 Two anti parallel
Microtubules 23 Protofilaments,in
turn of consisting