Cell Movement, Axon And Dendrite Growth

Question 1

How does wound healing happen?

Answer 1

Neutrophils and macrophages invade the site to clean up

Fibroblasts and epidermal cells proliferate and migrate. New cells and extracellular matrix fill in the wound.

Question 2

Diff b/w actins, micro tubules and intermediate filaments?

Answer 2

Actin- flexible, det. Surface cell shape, needed for locomotion.

Micro tubules - rigid, intracellular transport, cilia and flagella

Intermediate filaments - mechanical strength

Question 3

Cell locomotion involves what changes in cytoskeleton organisation?

Answer 3

1) protrusion (actin polymerisation)
2) attachment via integrins… Focal adhesions through actin
3) translocation of cell body (movement of u polymerised actin).. Traction by myosin moving along actin making cell body move forward
4) de adhesion at rear of cell

Question 4

What are focal adhesions?

Answer 4

How the cell attaches to the substrate
Cell has specific transmembrane proteins (integrins) that attaches to the extracellular matrix.

On the inside, it attaches to specific molecules which attach to the actin filament.

Chain of molecules that causes focal adhesion

Question 5

How do external molecules guide cells ?????

Answer 5

Bacteria have chemo attractants which send a signal to the receptors on the cell.

The cell signals inside the cell, for it to move forward.

Rac makes actin polymerise to protrude

Tho causes actin myosin contraction, at the back

Question 6

What does rho activation achieve?

Answer 6

More stress fibres

Integrins clustering and focal adhesion formation

Question 7

What does rac activation do?

Answer 7

Branches actin web in lamellipodia

Less stress fiber formation

Question 8

Diff bw axons and dendrites?

Answer 8

Axon: transmit outgoing information, long distances, some ribosomes, no golgi

Dendrites: receive and process incoming info, shorter and thicker, rich in ribosomes and Golgi, micro tubules have mixed orientation

Question 9

Diff bw neurite outgrowth in axons and dendrites

Answer 9

In axons…

Actin cytoskeleton is more dynamic
Micro tubules are more stable
Has kinesin
Heaps of receptors

Question 10

Examples of cell movement?

Answer 10

Gastrulation and neurulation in amphibians
Beating of cilia or flagella eg. Sperm
Neural crest cell migration (neural tube…), they colonise in the gut.

Brain neutrons migrate away from their site of production, travels up the process of another neutron.

Neutrophils migrate around adult body, chasing bacteria, or through chemotaxis (pipettes thing)