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Lab 305: Part V, Day 4
Stain and photograph the gel

There are many stains and tagged probes that allow us to visualize DNA. In our lab, we will stain the DNA with a fluorescent dye called ethidium bromide (EBr). EBr slides between the rungs of the DNA double helix. When excited by ultraviolet (UV) light, the EBr absorbs some of the energy and emits orange (visible) light.

  • Do not allow your skin, eyes, mouth, etc. to come in contact with ethidium bromide solution. Always wear goggles and gloves when working with this chemical.

  • If you accidentally spill ethidium bromide staining solution, notify the instructor. S/he will clean it up appropriately.

  • UV light can damage unprotected eyes and skin. Never look directly into an unshielded UV light source. FOTODYNE transilluminators are safe, since they will not turn on unless the acrylic safety shield is lowered over the gel.

  1. Bring your tray to the Staining Station.

  2. An operator, wearing gloves, will transfer your gel to a staining dish. The staining dishes contain a dilute EBr solution.

  3. The gel will be left in the EBr stain for 5-10 minutes, and then rinsed in distilled water for 5-10 minutes (to increase contrast and make the gels safer to handle).

  4. The operator will return your stained, rinsed gel to your plastic tray. Take your plastic tray to the Documentation Station.

  5. An operator at the Documentation Station will put your gel on the surface of the UV transilluminator. When the safety-lid is closed, this "box" emits ultraviolet light. The ultraviolet light makes EBr-coated DNA fragments glow.

  6. The operator may use one of several methods to record your results.

Background     Part I     Part II & III     Part IV     Part VI

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