SYNAPSE FORMATION

Question 1

WHAT HAPPENS WHEN A GROWTH CONE BECOMES A PRESYNAPSE

Answer 1

FILOPODIA RETRACTION
MEMBRANE AND EC GLYCOPROTEINS ADDED
PRESYNAPTIC VESICLES, DENSE ECM, PSD, RECEPTORS ACCUMULATE IN THE CLEFT

Question 2

CONTACTS MADE BY WHAT CAN INITIATE SYNAPSES

Answer 2

GROWTH CONE
AXON BRANCHES
DENDRITIC FILOPODIA

Question 3

IN SOME NEURONS, PRE-ESTABLISHED ……………………. MARK THE FUTURE SYNAPSE AND OTHER CONTACTS ARE ……………………
IN OTHER SITUATIONS, ……………….. CONTACTS, IF STABLE, RECRUIT SYNAPTIC COMPONENTS AND GO ON TO FORM FUNCTIONAL …………………..

Answer 3

SPECIALISED
INHIBITED
RANDOM
SYNAPSES

Question 4

BROADLY, WHEN DOES SYNAPTOGENESIS OCCUR

Answer 4

AS AXONS REACH TARGETS

Question 5

IS SYNAPTOGENESIS VARIABLE

Answer 5

YES

Question 6

NON NEURONAL NEIGHBOURS CAN ……………….. SYNAPSES. PRE SYNAPTIC SPECIALISATION CAN BE INDUCED OR ……………….. BY GUIDE …………… CELLS - OFTEN ………………
THESE CAN ALSO BE THE SAME NEURONS THAT ……………… THE AXONS

Answer 6

SHAPE
INHIBITED 
POST
GLIA
GUIDE

Question 7

MANY OF THE MOLECULES THAT ARE INVOLVED IN SYNAPSE …………………… ARE ALSO INVOLVED IN …………… GUIDANCE. HOWEVER SOME ARE HIGHLY ……………….TO SYNAPSE FORMATION. THESE INCLUDE NEUREXINS AND …………………. WHICH ARE CELL ADHESION MOLECULES.

Answer 7

FORMATION
AXON
SPECIFIC
NEUROLIGINS

Question 8

WHAT ARE NEUREXINS AND NEUROLIGINS

Answer 8

CELL ADHESION MOLECULES SPECIFIC TO SYNAPSE FORMATION

Question 9

WHAT IS THE STRUCTURE OF NEUREXINS AND NEUROLIGINS

Answer 9

LARGE IC DOMAINS THAT CAN ASSEMBLE COMPONENTS OF THE ACTIVE ZONE AND POST SYNAPTIC DENSITY

Question 10

NRX AND NL ALLOW SPATIAL SEGREGATION OF DIFFERENT ……………………/……………………..
INDIVIDUAL NEURONS CAN HAVE BOTH EXCITATORY AND INHIBITORY ……………..

Answer 10

INPUTS
OUTPUTS
INPUTS

Question 11

WHAT CLINICAL ASSOCIATIONS DO NEUREXINS AND NEUROLIGINS HAVE

Answer 11

AUTISM

SCHIZOPHRENIA

Question 12

WHAT DO EXCITATORY SYNAPSES HAVE THAT INHIBITORY SYNAPSES DO NOT

Answer 12

MORE DENSE POST SYNAPTIC DENSITIES

Question 13

DURING DEVELOPMENT, DIFFERENTIAL ………………. OF MULTIPLE MEMBERS OF ………….. AND NL FAMILIES ALLOWS DIFFERENT PRE SYNAPTIC NEURONS TO ………………. BETWEEN DIFFERENT ………….. SYNAPTIC PARTNERS.

Answer 13

EXPRESSION
NRX
SELECT
POST

Question 14

DIFFERENTIAL LOCALISATION OF NLS ON THE POST SYNAPTIC CELL ALSO ALLOWS SEPARATED WHAT

Answer 14

INNERVATION BY EXCITATORY AND INHIBITORY PRE SYNAPTIC NEURONS

Question 15

SINGLE NEURONS CAN HAVE MULTIPLE INPUTS

GIVE AN EXAMPLE

Answer 15

PURKINJE CELLS IN THE CEREBELLUM RECEIVE INPUTS FROM PARALLEL FIBRES, ML INTERNEURONS AND CLIMBING FIBRES IN A SPATIALLY RESTRICTED MANNER

Question 16

DESCRIBE ANOTHER FEATURE OF SYNAPSES

Answer 16

PLASTICITY

Question 17

WHAT ARE THE MODELS OF SYNAPSE FORMATION

Answer 17

1. DENDRITIC SPINES DEVELOP INDEPENDENTLY OF PRE SYNAPTIC INPUTS
2. PRESYNAPTIC INPUTS INDUCE SPINE FORMATION
3. DENDRITIC FILOPODIA INDUCE SYNAPSES IN AXONS GROWING PAST

IN ALL CASES PRE AND POST SYNAPTIC CELLS MUST WORK TOGETHER

Question 18

WHAT OCCURS IN ASSEMBLY OF SYNAPTIC COMPONENTS

Answer 18

CONTACTS (VIA CAMS OR SOLUBLE FACTORS EG WNT) BETWEEN DENDRITE AND AXON TRIGGERS INTRACELLULAR SIGNALS VIA CALCIUM FLUX.
THIS PROMOTES RECRUITMENT OF SCAFFOLDING PROTEINS PROVIDING FRAMEWORK FOR FORMATION OF COMPLEXES FORMING THE ACTIVE ZONE AND POST SYNAPTIC DENSITY

Question 19

GIVE EXAMPLES OF A SCAFFOLDING PROTEIN INVOLVED IN ASSEMBLY OF SYNAPTIC COMPONENTS

Answer 19

CASK

PSD-95

Question 20

WHY IS THE NEUROMUSCULAR JUNCTION A GOOD MODEL FOR SYNAPSES

Answer 20

EASILY ACCESSIBLE
SIMPLE
VERY LARGE
NOTABLE FOR ABILITY OF THE MOTOR TERMINAL TO ORGANISE COMPONENTS OF THE POST SYNAPTIC CELL

Question 21

BEFORE INNERVATION OF A NMJ WHAT IS THE DENSITY OF ACETYLCHOLINE RECPTORS

Answer 21

LOW DENSITY

Question 22

IN TERMS OF ACH RECEPTORS AND OTHER CHANNELS, WHAT DOES INNERVATION LEAD TO

Answer 22

PROGRESSIVE CLUSTERING TO THE EXTENT THAT EVENTUALLY ONLY FOUND BENEATH NERVE TERMINALS

Question 23

MOTOR NEURON ………………. CONTACT MYTOTUBULES AT ……………. AND NEW ……………. CLUSTERS CAN BE BORN AT SITES WITHOUT PRE CLUSTERS. THIS …………….. CLUSTERING IS ACTIVITY …………………… SUGGESTING THAT MOTOR NEURONS SECRETE AN INDUCING FACTOR: ……………………

Answer 23

NEURITES
RANDOM
ACHR
INDUCED
INDEPENDENT
AGRIN

Question 24

WHAT ARE THE STAGES OF RECEPTOR CLUSTERING

Answer 24

1. INITIALLY ACHR MRNA IS EXPRESSED AT LOW LEVELS IN MANY MYOTUBE NUCLEI AND ACHR CHANNELS ARE WIDELY DISTRIBUTED
2. AGRIN RELEASED BY MN BINDS TO THE MUSCLE SPECIFIC KINASE (MUSK) COMPLEX WHICH AUTOPHOSPHORYLATES AND RECRUITS RAPSYN WHICH RECRUITS CLUSTERS OF ACHR
3. OTHER FACTORS RELEASED BY THE SYNAPSING MN GROWTH CONE SUCH AS NEUREGULIN INDUCE ACHR EXPRESSION IN SYNAPTIC NUCLEI NEARBY
4. ACH IS ALSO RELEASE BINDING TO ACHR
5. WHEN ACTIVITY IS NOT ACCOMPANIED BY AGRIN, ACHR EXPRESSION AND CLUSTERING ARE INHIBITED.