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Star Republic: Guide for Biologists

Agarose gel electrophoresis

1. For a 1% agarose gel, weight 1 gram agarose per 100 ml 1x TAE buffer or 0.5x TBE buffer. Add to a 200 ml flask or bottle.

2. Melt agarose in a microwave oven. Keep the cap loose to prevent pressure build-up.

3. Use a gel cast or seal the open ends of a gel tray with mask tape to make a cast. Don't forget combs.

4. Let molten agarose to cool down a little. Add 0.5-1 ml 10 mg/ml ethidium bromide per 100 ml of agarose solution.

Caution ethidium bromide is a carcigen. Handle with care. Never boil agarose with ethidium bromide in a microwave oven reserved for heating human food.

5. Pour molten agarose to the gel cast, enough (0.5-1 cm) to submerge the comb teeth.

6. After the gel has solidified, remove the sealing tape and combs. Transfer the gel tray to a running tank, submerge the gel in 1x TAE if 1X TAE is used in Step 1 or 0.5x TBE running buffer is 0.5X TBE is used in step 2.

7. Mix sample DNA with loading dye, carefully load samples into wells.

8. Run the gel at 80-120 volts / 10 cm. DNA and dye are negatively charged, both run towards the positive electrode.

9. Make sure the power is turned on and the cables are correctly corrected. Stop the gel once the dye has run 1/2 to 2/3 of the gel length. See also Effective range of separation of DNAs in agarose gels and Dye migration in agarose and polyacrylamide gels.

10. Take the gel to a UV box, view the DNA under the UV ligth, and take a picture.

Warning: Don't expose your hands or face to UV without any protection. Wear gloves and protection goggles.