Exam (elaborations)
Psych 439 Final Exam Questions And Answers Latest Update
- Course
- PSYCH 439
- Institution
- Texas A&M University
Psych 439 Final Exam Questions And Answers Latest Update
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Solution 2024/2025Pepper
Psych 439 Final Exam Questions And Answers
Latest Update
presynaptic terminal ANS✔✔ contains neurotransmitter-filled vesicles and
machinery to release them (dumped into that space when signal arrives)
postsynaptic region ANS✔✔ includes on or more postsynaptic densities
(PSDs) that are opposite to the presynaptic terminal's active zone; receptors
to receive signal
synaptic cleft ANS✔✔ 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 ANS✔✔ 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 ANS✔✔ a cell adhesion molecule that helps cells grip to surfaces -
generally stickiness to help them stay at the target
, Solution 2024/2025
Pepper
Cadherins ANS✔✔ the 1st level of specificity; hemophilic specificity helps
axons and targets display some discrimination; activation of each induces
further differentiation
Beta-catenin ANS✔✔ 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? ANS✔✔ more receptors
available to receive signal so there is a stronger synapse there
Fragile X Syndrome ANS✔✔ 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 ANS✔✔ 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,
, Solution 2024/2025
Pepper
Neuroligin ANS✔✔ 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? ANS✔✔
arrival of the motor neuron axonal growth cone
Where are ACh receptors located on muscle? ANS✔✔ top of junctional folds
in clusters, nearest the axon terminal
Where are AChE found in muscle? ANS✔✔ in deep junctional folds
Steps to set up NMJ ANS✔✔ 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
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