Neuronal Motility

Question 1

Santiago Ramon y Cajal

Answer 1

Nobel prize 1906
golgi staining technique
synapses, growth cones, axonal transport

Question 2

where are growth cones found?

Answer 2

tips of all growing axons

Question 3

function of growth cones

Answer 3

direct nerve growth accurately to connect brain regions together correctly

Question 4

is growth proximal or distal? explain

Answer 4

distal
dye partciles on neurite shaft remain fixed relative to cell body
sever nerve from cell body - distal part still grows

Question 5

cajal 1900 thread

Answer 5

tie thread around nerve - materials build up on both sides

anterograde and retrograde axonal transport

Question 6

microfilaments

Answer 6

single filaments, bundles called F actin

Question 7

what are microfilaments polymers of?

Answer 7

g-actin

Question 8

microfilament shape

Answer 8

twisted helix of monomers

F actin polarised - addition of monomers faster at one end

Question 9

ends of microfilaments

Answer 9

barbed + end anchored to inner plasma membrane - fastest addition of monomers
pointed - end = disassemble monomers here

Question 10

what are MT polymers of?

Answer 10

alpha and beta tubulin

Question 11

MT ends

Answer 11

fast growing + ends all oriented distally in axons - nearer growth cone

Question 12

Where do MT extend to?

Answer 12

palm of growth cone

Question 13

rapid freeze fracture - cytoskeleton cross linking

Answer 13

MT-MT
MF-NF
NF-organelles
NF-membranes 
MF - membranes

Question 14

anterograde transport - materials

Answer 14

protein synthesis of NT, new membrane, new cytoskeleton

Question 15

retrograde transport - materials

Answer 15

recycle lysosomal products, act as signal

Question 16

retrograde transport signal example

Answer 16

NGF receptor complex from periphery to nucleus - signal damage if flow interrupted

Question 17

slow anterograde

Answer 17

NF and MT then actin

Question 18

fast anterograde

Answer 18

membrane bound organelles eg vesicles

Question 19

kinesin

Answer 19

protein present in axoplasm

Question 20

kinesin + MT + latex beads

Answer 20

kinesin bind beads and move anterograde

Question 21

dynein

Answer 21

retrograde transport

Question 22

dynein experiment

Answer 22

dynein add ATP and MTS
MT glides with + ends at front, coverslip move opposite direction
retrograde - towards minus end

Question 23

bidirectional MT transport

Answer 23

2 organelles can pass eachother going in opposite directions

Question 24

what causes power stroke to drive organelles?

Answer 24

conformational change of kinesin/dynein

Question 25

thing that questions growth being forward

Answer 25

particles on filopodial outer membrane swept back continuously suggesting rearward movement of cytoskeleton

Question 26

What is retrograde flow of filopodia coupled to?

Answer 26

coupled to dephosphorylation - energy conversion | myosin 1

Question 27

How is actin retrograde flow prevented?

Answer 27

talins bind to integrins which bind ECM (laminin, fibronectin and collagen) keep MT in place