Psych 439 Final Exam Review with Questions and Answers
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Course
Psych 439
Institution
Psych 439
Psych 439 Final Exam Review with Questions and Answers
presynaptic terminal ANSWER contains neurotransmitter-filled vesicles and machinery to release them (dumped into that space when signal arrives)
postsynaptic region ANSWER includes on or more postsynaptic densities (PSDs) that are opposit...
Psych 439 Final Exam Review with
Questions and Answers
presynaptic terminal ANSWER contains neurotransmitter-filled vesicles and machinery to
release them (dumped into that space when signal arrives)
postsynaptic region ANSWER includes on or more postsynaptic densities (PSDs) that are
opposite to the presynaptic terminal's active zone; receptors to receive signal
synaptic cleft ANSWER the area between two components filled with extracellular matrix,
composed of a variety of long-chain molecules that polymerize with one another (e.g.,
collagen, laminin, fibronectin)
3 stages of synapse maturation ANSWER 1. Initial contact - filopodia try to contact the
target, increased adhesion is the first level of specificity. First contact is mediated by
adhesion molecules like cadherins.
2. Assembly of synaptic machinery - synaptic vesicles start forming and the receptors start to
line up.
3. Stabilization of synapse - mature synapses are stabilized by the PSDs and weaker synapses
are pruned away. If they are stabilized, they are here to stay.
NCAM ANSWER a cell adhesion molecule that helps cells grip to surfaces - generally
stickiness to help them stay at the target
Cadherins ANSWER the 1st level of specificity; hemophilic specificity helps axons and
targets display some discrimination; activation of each induces further differentiation
Beta-catenin ANSWER links the intracellular domain of the cadherin receptor to actin
filaments inside the cell in order to anchor the synapse
,cadherin-beta-catenin complex is important for pruning of dendritic spines because the beta-
catenin is in short supply so it is competed over
Strongest spines get the most beta-catenin and so they are the ones that remain
What does a wider dendritic spine indicate? ANSWER more receptors available to receive
signal so there is a stronger synapse there
Fragile X Syndrome ANSWER an X-linked disorder that is caused by a trinucleotide repeat
(CGG), this repeats causes the X chromosome to become weak and break off; over
production of beta-catenin (used for pruning away weaker synapses) which results in a lack
of competition. Weak synapses will stay around and this causes motor deficiencies or
intellectual disabilities
Shows that more is not always better.
neurexin ANSWER inductive factor made by the growth cone; engages in cell-to-cell
signaling by binding to the neuroligin on the postsynaptic side. Important for vesicular
release and neurotransmitter release from presynaptic cells.
It helps set up SNARE complex and synaptotagmins,
Neuroligin ANSWER Inductive factor produced by the postsynaptic cell - where the ligand
binds.
Involved in scaffolding and anchoring PSD proteins so that all of the necessary proteins for
signaling are present underneath the presynaptic terminal.
What facilitates the maturation of the myotubes into muscle fibers? ANSWER arrival of the
motor neuron axonal growth cone
Where are ACh receptors located on muscle? ANSWER top of junctional folds in clusters,
nearest the axon terminal
, Where are AChE found in muscle? ANSWER in deep junctional folds
Steps to set up NMJ ANSWER 1. ACh continuously released by incoming growth cone that
will innervate the muscle cell, and the myotube expresses AChRs that respond to the NT
(ACh) - 1st step in a series of signals between the axon terminal and its target
2. Agrin is released by growth cone and binds to Lrp4
3. Binding of agrin to Lrp4 causes dimerization and autophosphorylation of internal domain
of MUSK
4. MUSK activates rapsyn
5. Rapsyn binds the intracellular domains of several AChRs and anchors them to the
microtubule of the muscle cell - this is why they are only found clustered under the synaptic
cleft
6. Neuregulin is released by the presynaptic cell and induces the muscle cell to express
certain subunits of AChR
agrin ANSWER a proteoglycan that is released from the growth cone and serves as a signal
and inductive factor at the NMJ; how we keep the AChRs anchored at the synapse instead of
floating around the bilayer
Neuregulin ANSWER A family of proteins that are motor neuron factors which induce
muscles to increase transcription of the various subunits of AChR at that NMJ; embedded in
motor neuronal axon membrane (can act via cell-cell contact); can be released but only
remain local
Bind to ErbB kinases on muscle fibers which boosts expression of AChR subunits
What drives depolarization in embryonic neurons? ANSWER influx of Ca2+ ions through vg
Ca2+ channels drives action potentials
NOT Na+ influx!
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