axonal growth

Question 1

what is the first step in neuronal identity & formation of connections

Answer 1

polarization

Question 2

where are growth cones located?

Answer 2

axonal tips

Question 3

what is the function of the growth cones?

Answer 3

determines direction of growth, guides extension of axon, key decision-making structure in axon pathfinding

Question 4

what structure is this statement describing?

“fan shaped sheet at tip of axon; contains actin filaments & microtubules”

Answer 4

lamellapodium

Question 5

what structure is this statement describing?

“fine processes extending out from lamellapodium; contain actin filaments; form & disappear rapidly”

Answer 5

filopodia

Question 6

what structure is primarily responsible for axon elongation? for dictating direction?

Answer 6

microtubules for elongation

F-actin for dictating direction

Question 7

what are examples of non diffusible molecules?

Answer 7

collagen
fibronectin
laminin
CAMs
semaphorins
ephrins

Question 8

are cadherins diffusible or non diffusible? attractive or repulsive?

Answer 8

non diffusible

attractive

Question 9

are semaphorins diffusible or non diffusible? attractive or repulsive?

Answer 9

non diffusible

repellent

Question 10

are ephrins diffusible or non diffusible? attractive or repulsive?

Answer 10

non diffusible

repellent

Question 11

are netrins diffusible or non diffusible? attractive or repulsive?

Answer 11

diffusible

attractive or repellent

Question 12

are slits diffusible or non diffusible? attractive or repulsive?

Answer 12

diffusible

repellent

Question 13

if the netrins are part of the DCC are they attractive or repellent?

Answer 13

attractive

Question 14

if netrins are repellent, what family are they part of?

Answer 14

UNC5

Question 15

what is the function of neurexin?

Answer 15

helps localize cytoskeletal elements, synaptic vesicles, active zone proteins and voltage gated Ca++ channels to the presynaptic membrane

Question 16

what is the function of neuroligin?

Answer 16

recruits neurotrnasmitter receptors and other post synaptic proteins

Question 17

what do “tropic interactions” ensure?

Answer 17

that each target cell is innervated by the right number of axons and each axon innervates the right number of cells

Question 18

how are axonal branching patterns refined?

Answer 18

via competition and synapse elimination

Question 19

what is the function of neurotrophins?

Answer 19

survival of a subset of neurons
form and maintain appropriate numbers of connections
elaboration of axonal and dendritic branches to support connections

Question 20

what are the two neurotrophin receptors?

Answer 20

Trk and p75

Question 21

what 3 things do neurotrophic interactions depend on?

Answer 21

1. neurotrophins secreted by target cells
2. neurotrophin receptors on neuron
3. intracellular signaling cascades present in neuron

Question 22

what 3 things do neurotrophic interactions determine?

Answer 22

1. numbers of neurons
2. shape of neurons (degree of aborization)
3. patterns of neuronal connections (number of synapses)

Question 23

are the non diffusible molecules in the EMC of the CNS largely attractive or repulsive? for the PNS?

Answer 23

in the CNS largely repulsive

in the PNS largely attractive