Lecture 1 - The Cytoskeleton Flashcards
State the diameters of the 3 filaments.
MFs: 7-9nm
MTs: 25nm
IFs: 10nm.
State the general structure of the 3 different filaments.
MFs: double helix of actin monomers.
MTs: hollow tube of tubulin dimers.
IFs: fibre composed of various of IF proteins, e.g. keratins.
State the role of the 3 different filaments.
MFs: cell movement, muscle contraction, cytokinesis.
MTs: scaffold, provides ‘track’ for the transport of vesicles/organelles, spindle fibres.
IFs: tensile strength.
What are lamellipodia and filopodia?
These are membrane protrusions that form at the leading edge and are rich in actin filaments.
What are the differences between lamellipodia and filopodia?
Lamellipodia are broader extensions typical of rapidly moving cells. Filopodia are thinner and are typical of slower moving cells.
Moving cells must attach to external surfaces they are travelling along using…
Focal adhesions, which are formed through integrins.
Give a brief description of the structure of globular actin.
- Globular protein, 2 lobes, each lobe has 2 domains.
- Domain I and III are connected by a hinge region, allowing them to move relative to one another. Forms a nucleotide binding cleft.
At which end is Cc lower?
Cc is lower at the (-) end. More likely to lose monomers.
How is the process of treadmilling maintained?
The Cc must be between that for the (+) end and (-) end.
Is actin’s ATPase activity higher in its polymerised or unpolymerised form?
Polymerised. Therefore, the longer the G-actin has been part of the filament, the more likely it is to be ADP bound.
The ADP-bound form has a reduced affinity for its neighbouring subunits. What does this mean?
More likely to dissociate.
