During the transmission of signals across a neuromuscular junction, which of the following happens first?

A. Acetylcholine binds to a receptor protein on the motor end plate.

B. The sodium and potassium ion gates on the motor end plates open.

C. Synaptic vesicles release acetylcholine molecules.

D. Synaptic vesicles move toward the axon terminals.

The correct answer is A acetylcholine binds to a receptor protein on the motor end plate

Explanation:

The neurotransmitter acetylcholine is released by the motor neuron during the transmission of signals across a neuromuscular junction.

The released acetylcholine then diffuses the synaptic cleft and binds to the receptor protein present on the membrane of muscle fibre.

This ultimately result in the influx of sodium ion inside the muscle cell thereby causing depolarization to generate an action potential.

C. Synaptic vesicles release acetylcholine molecules.

Explanation:

A neuromuscular junction is the junction between the terminal part of a motor axon and a motor plate (or neuromuscular synapse), which is the region of the plasma membrane of a muscle fiber (the sarcolemma) where the nerve and muscle meet allowing to trigger muscle contraction.

At the neuromuscular junction, the neurotransmitter used is acetylcholine, which is released by the synaptic vesicles at the beginning of the signal transmission process through the neuromuscular junction. The nerve fiber branches off at the end to form the end plate. which invaginates into the muscle fiber, but rests entirely on the outside of the membrane.