Question

Researchers investigating the regulation of neurotransmitter release from presynaptic neurons proposed a model in which CDK5, a protein expressed in axon terminals, inhibits the movement of synaptic vesicles to the presynaptic membrane... to test their model, the researchers used a modified version of green fluorescent protein...based on the model, which of the following best explains why a bright green fluorescence was observed following stimulation of a presynaptic neuron?

Answer 1

Answer:

"GFP contained in synaptic vesicles moved into the synaptic cleft by exocytosis."

Explanation:

Synaptic vesicles are small membrane sacs that carry neurotransmitters from the cell body where they are produced, to the presynaptic membrane of the terminal button where they are released. The release zone of the presynaptic membrane contains voltage-dependent calcium channels. When an action potential depolarizes the presynaptic plasma membrane, $Ca^{2+}$-channels open, and  $Ca^{2+}$ flows into the nerve terminal to trigger the exocytosis of synaptic vesicles, thereby releasing their neurotransmitters into the synaptic cleft