Question

During agarose gel electrophoresis, why do DNA fragments migrate toward the anode (positive electrode)?

Options

• DNA fragments are negatively charged molecules and are drawn toward the positive electrode in an electric field

• DNA fragments carry a net positive charge due to basic nitrogenous bases

• Agarose matrix imparts a strong negative charge to neutral DNA strands during electrophoresis

• DNA molecules bind covalently to positively charged ethidium bromide ions before migration

Answer 1

DNA fragments are negatively charged molecules due to their phosphate backbones. When placed in an electric field, they are forced to migrate through the matrix toward the positive electrode (anode).