Electrophoresis of DNA Under an electric field in an agarose gel, toward which electrode does DNA migrate?

Introduction / Context:Gel electrophoresis separates nucleic acids by size based on their movement in an electric field through a porous matrix. Understanding charge and directionality is foundational for interpreting bands and designing experiments.

Given Data / Assumptions:

• DNA backbone carries negative charges due to phosphate groups.
• Standard electrophoresis uses a buffer-filled gel with applied voltage.

Concept / Approach:Negatively charged molecules migrate toward the positive electrode (anode). Smaller fragments move faster through the matrix pores. Therefore, DNA moves from the cathode side toward the anode, forming size-dependent bands.

Step-by-Step Solution:

Verification / Alternative check:Tracking dyes and ladder standards consistently move toward the anode in agarose/TBE or TAE gels.

Why Other Options Are Wrong:

• Negative pole: opposite direction for negatively charged DNA.
• No migration: contradicted by routine lab practice.
• Both poles equally: impossible under a unidirectional field.

Common Pitfalls:Confusing electrode naming conventions; remembering that the anode is positive in electrophoresis setups.

Final Answer:Positive pole (anode)