The Cytoskeleton Flashcards
How were organelles originally believed to be found?
Floating freely in the cytosol.
What did we found out through microscopy about cell structure?
Cells have a cytoskeleton - fibres extending throughout the cell.
What does cyto mean?
Cell.
What is the cytoskeleton?
A network of microtubules, microfilaments, and intermediate filaments that extend throughout the cytoplasm and serve a variety of mechanical, transport, and signaling functions.
What 3 types of fibres make up the cytoskeleton?
Microtubules, microfilaments and intermediate filaments.
What are the roles of the cytoskeleton?
Physical support.
Motility.
Cell Regulation.
What does physical support entail?
Provides mechanical support (shape and rigidity) to cells.
Anchors organelles, structure and some proteins in their correct cellular locations.
Is cytoskeleton support static?
No, it’s dynamic. This means cell structure/shape can be changed.
What cell movement is the cytoskeleton involved in? (2 levels)
Movement of the whole cell across a substrate.
Parts of the cell move.
What is an example of a cell moving across a substrate?
A white blood cell “chasing” bacteria.
What does motility require?
The interaction of the cytoskeleton with motor proteins - regulators of motility.
How do motor proteins function?
They couple energy of ATP (/GTP) hydrolysis to movement.
What do motor proteins allow?
Whole cell movement along extracellular substrates.
The movement of organelles.
What do motor proteins do?
They stimulate the movement of cilia and flagella by “gripping” microtubules and moving them relative to each other.
What are motor proteins important in? (Examples)
Movement of microfilaments and muscle contraction.
How does the cytoskeleton allow organelle movement in the cell?
Vesicles attach to cytoskeletal “rails” to move from point A to point B.
Organelle movement example?
Neurotransmitters containing synaptic vesicles are made in the cell body but travel down the axons of nerve cells.
How are vesicles powered to “walk” along microtubules?
By nucleotide hydrolysis e.g. ATP.
What allows study of organelle movement?
Addition of drugs that inhibit or promote actin polymerisation.
What does the cytoskeleton allow communication between?
The cell and its environment.
What may the cytoskeleton do in response to the cell’s environment?
Change cell function/physiology.
How does the cytoskeleton respond to the extracellular environment?
Receptors on the plasma membrane pick up extracellular signals.
What are some extracellular signal examples?
Hormones, signals from other cells/the extracellular matrix.
