In agarose gel electrophoresis of nucleic acids, negatively charged DNA migrates in which direction relative to the electrodes?

Introduction / Context:
Agarose gel electrophoresis separates DNA by size based on movement in an electric field. Recognizing electrode polarity and DNA charge is fundamental for interpreting band positions and troubleshooting runs.

Given Data / Assumptions:

• Analyte: duplex DNA with a negatively charged phosphate backbone.
• Field applied across a submerged agarose gel.
• Electrode names: cathode (negative), anode (positive).

Concept / Approach:
Negatively charged molecules move toward the positive electrode. Thus, DNA migrates from the cathode (negative) toward the anode (positive). Orientation on the bench (left/right) is arbitrary; only electrode polarity determines the true direction.

Step-by-Step Solution:
1) Assign charges: DNA is net negative due to phosphates.2) Electric field: opposite charges attract; negative species move to the positive pole.3) Therefore, DNA migrates from cathode to anode.

Verification / Alternative check:
Dye fronts (e.g., bromophenol blue) are often tracked; their movement toward the anode coincides with DNA migration in standard TAE/TBE buffers.

Why Other Options Are Wrong:
Left to right / A to B: meaningless without electrode labels.Anode to cathode: opposite of the expected direction for negatively charged DNA.

Common Pitfalls:
Confusing physical left/right with electrode polarity, or swapping anode/cathode definitions.

Final Answer:
Cathode to anode