Answer:
Explanation:
The DNA is a chain of nucleotides. Each of them has a nitrogenous base (cytosine, thymine, adenine or guanine), a sugar called deoxyribose and a phosphate group.
The phosphate groups are negatively charged, and because of them the DNA molecule will be attracted to the positive pole during electrophoresis.
I'm attaching two figures: a nucleotide and a a DNA molecule (extracted from Organic Electronics, pp.73-112).