Synapses Flashcards

1
Q

What is the main role of glial cells in neuronal function?

A

Glial cells support and maintain neuronal function by providing structural support, regulating the extracellular environment, and facilitating neuronal communication.

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2
Q

What are the main structural and functional differences between ionotropic and
metabotropic receptors?

A

Ionotropic receptors are ligand-gated channels that permit the flow of ions when
stimulated. Metabotropic receptors are not directly associated with an ion channel; they
bind to G-proteins and initiate an intracellular cascade of events leading to changes in
membrane permeability.

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3
Q

How are ionotropic receptors affected by neurotransmitter concentration?

A

Ionotropic receptors are strongly activated when there is a high concentration of neurotransmitter released, making them highly responsive to strong stimuli.

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4
Q

What is the initial cause of synapse aging or neurodegeneration?

A

The disbalance in energy production at the synaptic terminal is often the starting point for synapse aging and neuronal decline.

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5
Q

How do specialized contact points help with neurotransmitter reuptake and recycling?

A

Specialized contact points help recycle neurotransmitters, preventing waste and ensuring they’re available for communication between neurons.

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6
Q

Parts of a Synapse

A

1) Presynaptic Terminal
2)Synaptic Vesicles
3) Neurotransmitters
4) Synaptic Cleft
5) Postsynaptic Membrane
6) Receptors
7)Postsynaptic Dendrite

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7
Q

Presynaptic Terminal

A

This is the end of the axon from the sending neuron, specifically, where neurotransmitters are released into the synaptic cleft.

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8
Q

Neurotransmitters

A

Chemical messengers that transmit signals from the presynaptic neuron to the postsynaptic neuron.

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9
Q

Synaptic Cleft

A

The small gap or space between the presynaptic terminal and the postsynaptic dendrite.

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10
Q

Postsynaptic Membrane

A

The membrane of the receiving neuron (usually a dendrite) that contains receptors for neurotransmitters.

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11
Q

Receptors

A

Proteins on the postsynaptic membrane that bind to specific neurotransmitters and initiate a response in the postsynaptic neuron.

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12
Q

Postsynaptic Dendrite

A

The part of the receiving neuron that receives the signal and conducts it toward the cell body.

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13
Q

What are the functions of the extracellular matrix in the brain?

A

1) Physical barrier
2) Regulates neural processes during brain development
3) Pays roles in physiological and pathological conditions, such as synaptogenesis and injury-related plasticity.

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14
Q

How does synaptogenesis occur?

A

Synaptogenesis begins with dendrites and axons growing and making contact, leading to the creation of presynaptic terminals where synaptic vesicles form, enabling communication between neurons.

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15
Q

Adhesive Factors (Cadherins and Protocadherins)

A

Play a role in anchoring the pre and post-synaptic terminals during synaptogenesis, helping to establish stable connections between neurons.

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16
Q

What impact can a dysfunctional cadherin-based adhesive system have on the human brain?

A

A faulty cadherin-based system could disrupt brain connectivity and information processing, contributing to neuropsychiatric disorders.

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17
Q

Post-synaptic density proteins

A

Forms structure of the post-synapse before channels or receptors are added.

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18
Q

What are the first and second step in synpatogeneis?

A
  1. Creation of adhesion between the pre and post-synaptic terminals
  2. Involves the formation of scaffolds that stabilzie the inital adhesion
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19
Q

What is the significance of the different shapes of dendritic spines?

A

The shapes of dendritic spines serve important functions and can change quickly depending on neuron activity, showing both functional and structural flexibility.

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20
Q

What is an electrical synapse, and how does it transmit signals?

A

An electrical synapse involves direct contact between pre and post-synaptic terminals through proteins like connexins that form gap junctions.

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21
Q

What is the significance of the “spine apparatus” in dendritic spines?

A

The spine apparatus, including the neck and head, acts as a filter to control which proteins can enter or exit the spine. It helps regulate the protein composition within dendritic spines.

22
Q

What is the role of the pre-axonal exclusion barrier in dendrites?

A

The pre-axonal exclusion barrier prevents certain RNAs or proteins from crossing over to the axon, ensuring that specific molecules are dedicated to dendrites.

23
Q

What is the Golgi outpost and its role in dendritic spines?

A

Specialized region within the dendrite where local proteins are synthesized and transported into dendritic spines to support their structure and function.

24
Q

What is the role of internal ribosomal entry sequences (IRES) in RNA?

A

IRES sequences signal the start of coding sequences in RNA.

25
Q

What happens behind the coding sequence of RNA?

A

Behind the coding sequence, there’s a 3’ untranslated region that binds to other protein complexes.

26
Q

How is RNA transported to the base of the synaptic spine?

A

The 3’ extension of mRNA serves as a signal for transporting RNA to the base of the synaptic spine.

27
Q

How does the length of the polyA tail affect RNA stability?

A

A shorter polyA tail leads to faster RNA degradation, while a longer tail keeps it stable.

28
Q

How is the RNA transport apparatus related to functional plasticity in the nervous system?

A

The RNA transport apparatus, involving elements like RNA cis-acting elements, neuronal transport granules, motor adaptor complexes, and local protein synthesis, is crucial for enabling adaptive changes in response to learning and experience, contributing to functional plasticity in the nervous system.

29
Q

What are RNA cis-acting elements in the context of RNA transport in neurons?

A

They are sequences within the RNA molecule that help regulate its transport and translation.

30
Q

What are neuronal transport granules, and how do they relate to RNA transport in neurons?

A

Neuronal transport granules move RNA inside neurons, helping genetic information reach its destination.

31
Q

What is the role of motor adaptor complexes in RNA transport in neurons?

A

Act like a molecular vehicles that move neuronal transport granules, ensuring RNA reaches its intended location.

32
Q

How do lysosomes and vesicles fit into RNA transport?

A

Lysosomes and vesicles join granules, creating an intermediate complex that links to the Kinesin motor complex for transport along microtubules.

33
Q

How is local protein turnover regulated in neurons?

A

Local protein turnover in neurons is regulated by proteasomes, which degrade and recycle proteins when they reach the end of their lifetime.

34
Q

What factors influence the efficiency of RNA translation?

A

RNA translation efficiency depends on signals affecting RNA structure and the availability of ribosomes in local translation complexes.

35
Q

What processes are vital for the functional plasticity of neuron?

A

Key aspects include 3’UTR diversity, mRNA localization, compartmentalization, and local mRNA regulation.

36
Q

What are the conceptual advantages of RNA localization in neurons? (4)

A

The advantages include metabolic economy, spatial restriction of protein activity, high temporal control, and ensuring the use of fresh protein

37
Q

What is the impact of Fragile X Syndrome on mRNA translation?

A

Fragile X Syndrome disrupts mRNA translation, causing uncontrolled RNA translation due to protein dysfunction caused by mutations.

38
Q

How does synapse-specific targeting work in translating proteins at active synapses?

A

Allows proteins to enter an active synapse based on the spine’s activity, acting like a filter to control protein entry.

39
Q

What is the role of synapse-specific capture or marking in functional plasticity?

A

Synapse-specific marking guides proteins to their proper locations within the synapse.

40
Q

How does local protein synthesis relate to functional plasticity?

A

Local protein synthesis, regulated by spine activity, determines which proteins can enter or exit the synapse through the spine neck filter, contributing to functional plasticity.

41
Q

What is activity-dependent recruitment in terms of plasticity?

A

Activity-dependent recruitment involves adjusting the strength of synaptic connections based on the level of spine activity.

42
Q

How does a high-frequency stimulus affect activity-dependent recruitment?

A

High-frequency stimuli activate the relevant receptors within the spine, triggering the insertion of more receptors and transport vesicles into the membrane.

43
Q

What happens with low-frequency stimuli in activity-dependent recruitment?

A

Low-frequency stimuli reduce synaptic strength by destabilizing actin, making dendritic spines less efficient, leading to the removal of NMDA receptors and altering the spine’s activity based on calcium levels.

44
Q

What is the role of the RARC(Receptor Activity-Regulated Cytoskeleton-Associated Protein) protein in synaptic strengthening?

A

RARC protein binds to actin and plays a crucial role in memory formation and the strengthening of synaptic contacts.

45
Q

How does Arc protein affect synaptic changes?

A

Arc protein binds to actin and reshapes the spine head, leading to structural enlargement and functional activation of the synapse.

46
Q

How can manipulating the density of glutamatergic synapses affect synapse function?

A

Modifying the density of glutamatergic synapses, either by increasing or decreasing it, can disrupt synapse function, potentially leading to a variety of pathological conditions.

47
Q

How does synaptic density change with age?

A

Synaptic density increases in early development, but decreases as the brain matures through a pruning process, removing excess connections and keeping only essential ones.

48
Q

Mitochondria and synaptic aging:

A

As mitochondria age, their decline affects synaptic function since they produce essential energy for synapses, potentially leading to age-related changes in synaptic connections.

49
Q

What does the release of cytochrome c indicate in mitochondria?

A

The release of cytochrome c is an indicator of mitochondrial aging and can affect synaptic performanc

50
Q

How does mitochondria age?

A

Mitochondria can age due to the accumulation of mutations in their circular genome, leading to changes in their structure and function over time.

51
Q

SA: Summarize experimental evidence that synaptic vesicles are recycled in the axon
terminal.

A

Synaptic vesicle recycling was confirmed through an experiment using horseradish peroxidase (HRP) at a frog neuromuscular junction. HRP was applied and neurons stimulated. Observation showed HRP initially in coated vesicles, then in endosomes, and finally in newly-formed synaptic vesicles.

52
Q

SA: What are the three major types of ionotropic glutamate receptors, and why were they
given their specific names? Why are two types of these receptors considered to be
particularly important?

A

The three main ionotropic glutamate receptors are NMDA, AMPA, and kainate.
- They’re named after substances that activate them.
- NMDA and AMPA receptors are vital as they’re found in most excitatory synapses in the brain.