Final answer:
DNA molecules migrate toward the positive pole in electrophoresis due to their negatively charged backbone, which is attracted to the positive electrode. The rate of migration is influenced by the electric field's strength, as well as the size and shape of the DNA.
Step-by-step explanation:
The aspect of DNA's structure that causes it to migrate toward the positive pole during processes such as agarose gel electrophoresis is its negative charge. The backbone of the DNA molecule is composed of sugar and phosphate groups that contain negatively charged phosphate groups.
When placed in an electric field during electrophoresis, the negatively charged DNA is attracted to the positive electrode. Molecules with a smaller size experience less friction in the gel matrix and can travel faster than larger molecules.
In this process, classical electrostatics plays a significant role, as the electrostatic force holds the molecule together, gives it structure, and plays a role in how it moves in an electric field. The migration rate of DNA through a gel is also affected by factors such as the strength of the electric field (E) and the molecule's shape and size.