In brain chemistry, synapses are very important. Synapses have a number of different forms but have two basic varieties:. excitatory and inhibitory. Excitatory synapses make it more likely that a neuron will send its message to other neurons, whereas inhibitory synapses make it less likely that a neuron will send its message.
Let Red = R and Blue = r
so when crossed ; RR , Rr, rr
thus the [ Rr ] are pruple !!!