Final answer:
Glutamate is an excitatory amino acid, while GABA and glycine are inhibitory amino acids involved in synaptic transmission.
Step-by-step explanation:
Amino acids glutamate, GABA, and glycine are neurotransmitters involved in inhibitory synaptic transmission. Glutamate is considered an excitatory amino acid because it causes depolarization of postsynaptic cells. On the other hand, both GABA and glycine are considered inhibitory amino acids because they cause hyperpolarization of postsynaptic cells.