Synaptic gaps separate neurotransmitter receptor sites from

the presynaptic neuron

Explanation:

When an electrical signal reaches the end of a neuron, it triggers the release of small sacs called vesicles that contain neurotransmitters. These sacs spill their contents into the synapse, where neurotransmitters move through space toward neighboring cells. These cells contain receptors where neurotransmitters can bind and trigger changes in cells.

Upon release, the neurotransmitter crosses the synaptic gap (which separates neurotransmitter receptor sites from the presynaptic neuron) and binds to the receptor site on the other neuron, stimulating or inhibiting the receptor neuron depending on what the neurotransmitter is. Neurotransmitters act as a key and the receptor site acts as a block. It takes the right key to open specific locks. If the neurotransmitter is able to function at the receptor site, it will cause changes in the recipient cell.

unicellular organisms, like bacteria, are able to perform all life functions within one single cell. multicellular organisms need many different types of cells to carry out the same life processes. each of these special types of cells has a different structure that it perform a specific function.