Tryptophan self-controls its synthesis. If we have a large amount of tryptophan in the sense that it exceeds, tryptophan would act as a co-repressor which prevents synthesis of more enzymes for its production. Hope this answers the question.
Excitatory neurotransmitters cause the neuron to fire, and Inhibitory neurotransmitters cause the neuron not to fire.
Impulses are the signals passed from one neuron to another on the action of a stimulus. The impulses passed can be electrical or chemical. Neurotransmitters are the chemical molecules that help in the transfer of impulses between two neurons.
Chemicals like epinephrine, norepinephrine, and glutamate when released from the synaptic cleft of one neuron activate the receptors of other neurons, thereby initiating the other neuron to fire. These chemicals are called excitatory neurotransmitters.
Chemicals like GABA and glycine, when released from the synaptic cleft of one neuron do not activate the receptors of other neurons and hence the neurons will not fire the impulse. These chemicals are called inhibitory neurotransmitters.
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Answer:
nucleus, cytoplasm, mitochondria
Explanation:
Answer: SECONDARY CELL WALL.
Explanation: When cell wall grow,it becomes thickened,then it further deposits new layers of a different material (different from that of the primary cell wall) from where secondary cell wall is formed.
This secondary cell wall is made up of cellulose,hemicellulose,and lignin.
They function in providing additional strength,support, rigidity to cells and the larger plant.