Here's why:
* DNA's Phosphate Backbone: DNA is made up of a sugar-phosphate backbone. The phosphate groups in this backbone are negatively charged.
* Electrophoresis: Electrophoresis uses an electric field to separate molecules based on their size and charge. The apparatus has a positive electrode at one end and a negative electrode at the other.
* Migration: Since DNA is negatively charged, it is attracted to the positive electrode. This causes it to move towards the positive pole during electrophoresis.
Note: Smaller DNA fragments migrate faster than larger ones because they experience less resistance from the gel matrix.
