The Cytoskeleton Flashcards
What is the Cytoskeleton?
(Shape strength movement)
A large dynamic network of protein filaments which supports the cell
-Ensures cell shape remains the same
-Prevents the cell from being damaged
-Provides a mechanism by which things can move within the cell
What are the three kinds of protein filaments?
-Actin Filaments
-Microtubules
-Intermediate filaments
What do the Actin Filaments do?
They maintain the shape of the cell’s surface, as well as whole-cell location, pinching one cell into two
What do the Microtubules do?
Position of organelles, intracellular transport and mitotic spindles
What do the intermediate filaments do?
Mechanical strength
How do filaments remain stable?
By insuring multiple filaments are held together through non covalent bonds
What bonds hold filaments together?
Hydrogen bonds and van der Waals forces
What are some characteristics of Actin Filaments (construction and use)
Formed by the polymerisation of G actin
When polymerised into chains the form to create a protofilament that twists to from a helix (F-Actin)
What does the large cleft in F-Actin do?
Binds ATP
What is special about the orientation of G-Actin molecules in F-Actin
They are all facing the same way
How is F-Actin polarity shown?
Barbed (+) end and pointed (-) end
How big is each 180 degree twist in F-Actin
37nm, therefore one whole twist = 74nm
What is nucleation
The first step in the formation of a new structure via self-assembly
How does G-actin form F-actin?
G-actin is activated through ATP, which is then bound into forming the unstable di and stable trimers, eventually forming F-actin when each of these molecules combine
What is the critical concentration
Cc= When G actin monomers and F-Actin are in equilibrium
