Cell Biology of Neurons (4/5) Flashcards
(47 cards)
What key features are important for neuron function?
- Electrical excitability 2. Polarization
What are the two compartments of the neuron?
The somatic dendritic compartment consists of the dendrites and cell body. The axonal comparment consists of initial axonal segment (hillock) and axon.
What are the two compartments of the epithelial cell?
The baso-lateral compartment. Faces more cells. The apical compartment consists of tight junction and microvilli. Faces lumen.
What are the stages of development of neurites
- Lamellipodia 2. Immature neurites 3. Axon formation 4. Dendrite formation 5. Further maturation
During neuronal migration, what do the neurons use to migrate along the radial cell?
Leading process
What does the leading process develop into?
Dendrites
What does the trailing process develop into?
Axon
How is neuronal polarity established and maintained?
- Selective delivery of protein 2. Selective fusion of membrane 3. Selective retention of protein
What proteins are selectively delivered to dendrites?
Neurotransmitter receptors
What proteins are selectively delivered to axons?
Voltage-gated Na/K channels
What proteins mediate vesicle fusion with the plasma membrane?
SNARE proteins
What restricts unwanted mixing between proteins of the axon and dendrite?
Diffusion barrier at axon initial segment
How is neuronal polarity maintained when neuron is young?
A lot can move around early. 1. lateral diffusion 2. endocytosis 3. retention in lipid rafts
How is neuronal polarity maintained when neuron is older?
Membrane protein-cytoskeletal interactions at axon hillock prevent lateral mixing of membrane proteins between axons and dendrites
Describe organelles in axons vs dendrites
Axons do not have all organelles. Dendrites have most
Describe protein difference in axons vs dendrites
Axons have tau protein; dendrites have MAP2 (microtubule associated proteins)
What are general cellular components of a neuron?
Plasma membrane, cytosol, cytoskeleton
What are microtubules?
Part of cytoskeleton; They are tubes of 13 protofilaments made from alpha, beta dimers (50 kD each)
What is beta tubulin?
Subunit in MT; GTP or GDP Binding; plus end
What is alpha tubulin?
Subunit in MT; GTP binding; minus end
What influences growth of microtubules.
When rate of subunit addition exceeds rate of GTP hydrolysis it leads to a growing microtubule
When rate of GTP hydrolysis exceeds rate of subunit addition it leads to a shrinking microtubule
What is the function of microtubules in neurons?
Functions for axonal growth and guidance. Provides tracks for long-range protein and organelle transport between the neuronal cell body and the nerve terminal.
What molecular motors mediates organelle transport between the neuronal cell body and the nerve terminal?
Kinesin motors: mediate either plus or minus end-oriented transport. Dynein motors: mediate only minus end-oriented transport
Describe microtubule polarity in axons
all MT plus ends are oriented towards terminal