motility

Question 1

stimuli to move

Answer 1

organogenesis and morphogenesis wounding growth factors/chemoattractants dedifferentiation (tumours)

Question 2

How to move?

Answer 2

specialized structures (focal adhesion, lamellae, filopodium)

Question 3

how do specialised structures interact

Answer 3

An analogy to cell movement is wall climbing; first the filopodia are extended to find support to hold onto (focal adhesions) • Lamellipodia then attach to the substratum to provide support during movement • Movement of the cell body occurs, with retraction of the dorsum and movement forward

Question 4

what are focal adhesions

Answer 4

sites at which the cell attaches to proteins which make the ECM

Question 5

what is Filamentous actin

Answer 5

lies beneath the membrane, and hooks the focal adhesions to the cytoskeletons via integrins On the intracellular side, integrins interact with various cytoskeletal proteins to form a plaque

Question 6

what protein overlies protrusions of filopodia

Answer 6

vinculin

Question 7

why is control of cell movement needed

Answer 7

within a cell to coordinate what is happening in different parts regulate adhesion/release of cell-ECM receptors from outside to respond to external influences – sensors directionality

Question 8

what are the 2 types of cell motility

Answer 8

Hapoptatic motility is movement with no direction Chemotactic movement is movement in which the cell senses a stimulus and goes towards it In both cases, cell movement involves changes cell shape

Question 9

what 2 was can actin be found in

Answer 9

Actin can be found as small soluble globular monomers (G-actin), ir in a large polymerized filamentous polymer (F-actin)

Question 10

how does actin filament polarity change in response to stimulus

Answer 10

If there is a signal like a nutrient source at one end of the cell, the F-actin at the other end will disassemble and the subunits will diffuse to the side with the signal. There is reassembly of the subunits at the new site and this facilitates movement.

Question 11

Arrangement of the actin filaments allows variety of what

Answer 11

different structures to be made The cell cortex has a random gel-like arrangement to provide support to the plasma membrane • Stress fibres have anti-parallel arrnagment, forming contractile bundles • Filopodium have tight parallel bundles