A test organism develops a genetic mutation that causes neurons to develop without synaptic knobs. How will this impact neuronal function/?

The electrical signal will not be converted into chemical signal.

Explanation:

The synaptic knob is the bulbous enlargement also called synaptic terminal preset at the end of the axon.

The synaptic knob is a living cell and thus contains all the living features but they also contain the vesicles which store the neurotransmitters, therefore, synaptic knob acts as a site which converts the electrical signal into a chemical signal. The released neurotransmitter from the synaptic knob interacts with the post neuron or recipient neuron.

If the mutation develops in the neurons which result in the formation of neurons without synaptic knob therefore the electrical signal will not be converted into a chemical signal and thus signal will stop.