What process occurs when neurotransmitters are released into the synaptic cleft?

• A. Endocytosis
• B. Exocytosis
• C. Translation
• D. Transcription

Answer: (B)

When neurotransmitters are released into the synaptic cleft, the process that takes place is called exocytosis. This process involves vesicles, which contain the neurotransmitters, fusing with the presynaptic membrane of the neuron. As these vesicles merge with the membrane, they release their contents—neurotransmitters—into the synaptic cleft. This is a crucial step in neurotransmission, allowing the neurotransmitters to bind to receptors on the postsynaptic neuron, leading to the propagation of the neural signal.

Endocytosis, in contrast, involves the uptake of materials into a cell, which is not relevant to the release mechanism being described. Translation and transcription are processes related to gene expression and protein synthesis, not directly involved in neurotransmitter release. Thus, exocytosis specifically describes the release of neurotransmitters in synaptic transmission.