Cell motility Flashcards
What does cell motility need?
Energy
Guidance
Mechanical interaction with something outside the cell (in order to move in a 3D environ)
Swimming (microtubules) vs crawling (actin microfilaments)
What are micro tubules?
→ hollow tubes of a and b tubulin
Polar
Describe the axoneme of a microtubule
9+2 microtubule assembly
9 outer doublets
Radial spokes
Inner pair
Dynein arms = motor proteins
Polarity across the width and length of the tubule
What are the dynein arms of a microtubule like in an isolated doublet.
(insert pic)
Dynein (+ ATP) produces sliding motion
What cuases the dynein arms of a microtubule in a flagellum to bend?
+ Nexin crosslinkers causes microtubule bending
How are actin molecules different to microtubules?
Actin:
- narrower
- more flexible
- Solid
What is mysoin?
the microfilament motor protein that binds to actin
What type of filament is present in cilia/flagella and what kind of motor protein is associated?
Microtubule + dynein
What type of filament is present in cytoskeleton/muscle and what kind of motor protein is associated?
Actin + myosin
Describe the structure of myosin
(pic)
What do troponin/tropomyosin do?
block myosin from actin binding sites
How is muscle contraction regulated by calcium levels
Calcium ions bind to troponin on the actin filament, this changes troponin’s shape, exposing the binding sites for myosin to bind
