Questions: Question 4 Question: What is the role of monoamine oxidase in the synaptic cleft? Synthesizes neurotransmitters Degrades neurotransmitters Recycles neurotransmitters Transports neurotransmitters

The answer is the second one: degrades neurotransmitters.

Explanation for each option:

1. Synthesizes neurotransmitters: This is incorrect. Monoamine oxidase (MAO) does not synthesize neurotransmitters. Instead, it is involved in the breakdown of neurotransmitters.

2. Degrades neurotransmitters: This is correct. Monoamine oxidase is an enzyme that degrades monoamine neurotransmitters such as serotonin, dopamine, and norepinephrine in the synaptic cleft. This degradation helps regulate the levels of these neurotransmitters and terminate their action.

3. Recycles neurotransmitters: This is incorrect. Monoamine oxidase does not recycle neurotransmitters. Recycling of neurotransmitters typically involves reuptake mechanisms where neurotransmitters are taken back into the presynaptic neuron.

4. Transports neurotransmitters: This is incorrect. Monoamine oxidase does not transport neurotransmitters. Transport of neurotransmitters is usually carried out by specific transporter proteins in the neuronal membrane.

Summary: Monoamine oxidase plays a crucial role in the synaptic cleft by degrading neurotransmitters, thereby helping to regulate their levels and terminate their signaling actions.