Question

Dopamine acetylcholine and GABA are:
A) Hormone
B) Enzyme
C) Synthetic vitamin
D) Neurotransmitters

Answer 1

Hint:
These are usually small molecular weight paracrine signal molecules, such as amino acids, amines, purines, and neuropeptides. These molecules are synthesized in the presynaptic terminals of neurons and released on stimulation.

Complete step by step answer:
Some neurotransmitters stimulate neurons to fire, while others inhibit firing. The effect of the neurotransmitter comes out by its binding with receptor proteins on the membrane of the postsynaptic neuron. GABA (gamma-aminobutyric acid) is an inhibitory neurotransmitter and Dopamine is generally excitatory but may be inhibitory at some sites. So both of these are neurotransmitters.
Acetylcholine is a cholinergic neurotransmitter synthesized from choline and acetyl coenzyme A by the enzyme choline acetyltransferase. It is synthesized in the axon terminals. After synthesis, it is released by the process of exocytosis in the synaptic cleft. GPI-linked enzyme acetylcholinesterase located on the postsynaptic membrane breaks acetylcholine into choline and acetyl coenzyme A . Insecticides like malathion, parathion, nerve gas like sarin, and DIPF inhibit the activity of acetylcholinesterase. The response is mediated by the binding of acetylcholine with the acetylcholine receptor present in postsynaptic cells. Acetylcholine receptors have been divided into two main types: Nicotinic and muscarinic acetylcholine receptors.

Option ‘D’ is correct

Note:
Opening of acetylcholine receptor channels following the binding of acetylcholine produces a net depolarization in the postsynaptic cell. This localized depolarization triggers the opening of voltage-gated sodium channels, leading to the generation and conduction of an action potential in the postsynaptic cell plasma membrane.