GRE Subject Test: Biochemistry, Cell, and Molecular Biology › Help with Neural Specialization
Neurons transmit signals via transmission of an electrical signal called an action potential. Which integral membrane protein is crucial for the rising phase of an action potential?
Voltage-gated sodium channels
Voltage-gated potassium channels
Metabotropic glutamate receptors
Ligand gated calcium channels
Ligand gated sodium channels
Voltage gated sodium channels allow the influx of sodium to quickly depolarize the neuron and generate the action potential. They are voltage gated, meaning they open in response to changes in membrane potential, thus providing the positive feedback required to get such a dramatic change in membrane potential once threshold has been reached. The other channels listed are not involved with the rising phase of the action potential.
In synaptic transmission, the __________ of the pre-synaptic cell can make either a chemical or electrical synapse with a __________ of the post-synaptic cell.
axon . . . dendrite
dendrite . . . axon
soma . . . dendrite
axon . . . nucleus
spine . . . dendrite
Of all the choices, axon and dendrite are the best answers to fill in the blanks because the axon is typically the pre-synaptic structure and the dendrite is the post-synaptic structure. In each of the other selections at least one of the choices does not make sense as a post/pre synaptic structure, or has nothing to do with synaptic transmission.