Study guide 5 - Questions 66-84

What are the three components of the cytoskeleton in order of size?

Microfilaments, neurofilaments, microtubules.

What are the structural components and functions of microtubules?

Microtubules are made of tubulin and provide structural support and pathways for transport.

Where are each component of the cytoskeleton located in the neuron?

Microfilaments are found throughout the neuron, neurofilaments mainly in the axon, and microtubules extend from the cell body into the axon and dendrites.

What is polymerization/depolymerization?

Polymerization is the process of monomers joining to form polymers, while depolymerization is the breakdown of polymers into monomers.

Which protein stabilizes microtubules?

Tau protein stabilizes microtubules.

What is a protofilament?

A protofilament is a linear chain of tubulin dimers that makes up the wall of a microtubule.

What determines the location and orientation of microtubules?

The centrosome and molecular motors determine the location and orientation of microtubules.

How do neurofibrillary tangles come about?

Neurofibrillary tangles result from the hyperphosphorylation of tau protein, leading to microtubule destabilization.

Which cytoskeletal protein is only present in neurons vs in glia?

Neurofilaments are primarily present in neurons.

Which feature of neurofilament proteins permits maintenance of axon diameter?

The length and spacing of neurofilaments maintain the axon diameter.

Which cytoskeletal elements change dynamically versus which is stable?

Microfilaments change dynamically, while neurofilaments and microtubules are more stable.

Mutations in which neurofilament proteins lead to which neurodegenerative diseases?

Mutations in neuronal intermediate filaments can lead to conditions such as amyotrophic lateral sclerosis (ALS) or frontotemporal dementia.

What is a growth cone?

A growth cone is a dynamic structure at the tip of a growing axon or dendrite that guides the extension of the neurite.

How do microfilaments contribute to the maintenance of protein complexes?

Microfilaments provide the scaffold for anchoring and organizing protein complexes within the neuron.

What are actin rings and what are their functions?

Actin rings are structures composed of actin filaments that help in maintaining the shape of dendritic spines and facilitate synaptic function.

What is the functional significance of microfilament polymerization in dendritic spines?

Microfilament polymerization in dendritic spines contributes to spine growth and stability, enhancing synaptic strength.

What are the stages of dendritic spine maturation?

The stages of dendritic spine maturation include filopodia, early and mature spines.

How do the four microfilament-associated proteins we discussed alter spine morphology (i.e., shape)?

These proteins modulate actin dynamics, affecting the formation and stability of dendritic spines.

What is the functional difference between a filopodia and a mushroom spine?

Filopodia are slender and exploratory structures, while mushroom spines are more stable and have a broader head that is involved in synaptic transmission.