As we know the outer and the inner lining of our cell membranes has metallic ion composition basically the Na+ and K+,this provides the potential for the nerve impulses to
travel from one neuron to another.As per the cells goes,there are different types of materials that makes up the composition of cells such as adipocytes ,erythrocytes, leucocytes etc.So as adipocytes has fats on them so they can conduct electricity more than other cells.These lining of adipose in our provides the stronghold barrier against electricity damage but our skin which composed of dead cells when also provides a resistance of 10^5 ohm but when wet the resistance drops drastically to 200 ohm.
Now if the amount of electricity passes through the
body exceeds the threshold value,the
heating effect of the electricity will destroy all the organic
elements and thus death.
As far as cells goes, there is no difference of ac or dc current flowing through but only the amplitude is important which is constant for dc but variable for ac.But it may have effect on brain cells as electromagnetic field is produced in brains.