Final answer:
The assertion that acetylcholine is actively transported from the pre-synaptic to the post-synaptic membrane is false. Acetylcholine diffuses across the synaptic cleft and binds to receptors on the post-synaptic membrane, which is a passive process not requiring active transport.
Step-by-step explanation:
The statement that acetylcholine (ACh) is actively transported from the pre-synaptic membrane to the post-synaptic membrane is false. In the process of neurotransmission, when an action potential reaches the axon terminal of the presynaptic neuron, synaptic vesicles containing ACh merge with the presynaptic membrane.
This event is triggered by an influx of calcium ions into the cell, which facilitates the fusion of the vesicles with the membrane and the subsequent release of ACh into the synaptic cleft.
Acetylcholine then diffuses across the synaptic cleft by passive means and binds to acetylcholine receptors on the postsynaptic membrane. These receptors then initiate a change in the membrane potential of the postsynaptic cell by allowing the entry of sodium ions which leads to depolarization and potentially the generation of another action potential if the threshold is reached.
Once ACh has completed its function, it is broken down by the enzyme acetylcholinesterase, and the resultant choline is taken back up into the presynaptic neuron to be used again for the synthesis of new ACh molecules. Hence, acetylcholine diffusion is the key process involved in crossing the synaptic cleft, not active transport.