Transcript Explain the importance of the cytoskeleton in providing mechanical

Cell ultrastructure
• Explain the importance of the cytoskeleton
in providing mechanical strength to cells,
aiding transport within cells and enabling cell
movement.
• Recognise the structures flagella/undulipodia
and cilia, and outline their functions.
The detail of the inside of cell is called the
cell’s ultrastructure.
Functions of the cytoskeleton
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Gives cell shape (tension)
Mechanical resistance to deformation
Actively contracts allowing cells to migrate
Intracellular transport
Cytokinesis
Forms specialised structures
Chromosome separation in cell division
Role in cell signalling pathways and
endocytosis
• https://www.youtube.com/watch?v=YTv9It
Gd050
What is the cytoskeleton made from?
Network of fibres made of protein
• Microfilaments:
- made of actin (subunits)
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- 3-6 nm diameter
- ‘movement’ (migration) of cells using polymerisation
creating a ‘leading edge’
- movement within cells (intracellular transport)
- cytokinesis
Intermediate filaments:
-made of different proteins
-10nm diameter
-generate tensile strength
-network for organelle positioning
-in desmosomes structure
- cytoskeleton of nucleus
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Microtubules:
- hollow cylinders with diameter of 23nm
- made of protein called tubulin
– Forms spindle in cell division
– Cilia, centrioles and flagella are made from these
– Cell signalling
• Other proteins (motors) on the microtubules
and microfilaments use ATP to move
organelles along the fibres:
– Chromosomes during mitosis
– Movement of vesicles from endoplasmic reticulum
to Golgi apparatus
Flagella (undulipodia) and cilia
• Hair-like extensions that
stick out from surface of
cells.
• Cylinder that contains 9
microtubules arranged in
a circle and 2 in a central
bundle.
• A sperm cell tail
(undulipodium) can move
the whole cell.
• In ciliated epithelial
tissue the sweeping
movements of the cilia
move substances (mucus)
• Undulipodia and cilia move because the
microtubules use energy from ATP.
• Undulipodia are long and usually occur in ones
or twos on a cell.
• Cillia are short (less than 10 μm long) and
often occur in large numbers.
• Some bacteria have
flagella
• Different internal
structure to
undulipodia.
• They are ‘motors’ –
made of a spiral
protein (flagellin)
attached by a hook to a
protein disk at the
base.
• Using energy from
ATP, the disk rotates,
spinning the flagellum.