Molecular Foundations of Neural Cells
From molecules to cellular identity
Cellular specialization
Neurons and glia share core eukaryotic machinery, but their molecular specialization supports distinct roles in excitability, trophic support, and information transfer. Neuronal polarity depends on asymmetric trafficking, cytoskeletal organization, and compartment-specific protein sorting.
Core idea
Cell identity in the nervous system is encoded by gene expression programs, membrane composition, and the spatial organization of signaling proteins.
Membranes and excitability
The neuronal membrane contains high densities of ion channels, pumps, and transporters that create electrochemical gradients. The resting membrane potential arises from selective permeability and active maintenance by the Na/K-ATPase. Membrane microdomains such as lipid rafts can cluster receptors and scaffold proteins, altering signaling kinetics.
Which feature most directly contributes to the resting membrane potential of a neuron?
Selective permeability, especially to K, is the primary determinant of resting membrane potential.
Correct answer: Selective membrane permeability to ions
Name one membrane protein that maintains ionic gradients essential for neuronal excitability.
The Na/K-ATPase uses ATP to maintain sodium and potassium gradients.
Correct answer: Na+/K+-ATPase
Major cellular compartments
| Compartment | Molecular role |
|---|---|
| Soma | Protein synthesis and integration of signals |
| Axon initial segment | Action potential initiation |
| Dendritic spine | Synaptic reception and plasticity |
| Glial membrane | Metabolic support and homeostasis |
Essential molecular players
What is the main functional consequence of the axon initial segment?
The axon initial segment is enriched in voltage-gated sodium channels and initiates action potentials.
Correct answer: It is the primary site of action potential initiation