Im confused, help please

What initially causes a nerve impulse? release of enzymes out of the neuron movement of chemicals into the dendrites of the neuron pathogens attacking the dendrites of the neuron red blood cells bathing the neuron

Anormal appearing couple is found to be heterozygous recessive for albinism both have the genotype aa the gene responsible for albinism is recessive to the normal pigment-producing gene what are the changes of their children being albino

Where does the information about where each transcription factor binds originate?