Download EXPLORING ELECTROPHORESIS Procedure

EXPLORING ELECTROPHORESIS
MATERIALS PER LAB TEAM:
Power Supply , Gel box, 2-3 NL Salt Solution (1M NACL), 400 ML Distilled Water, 1-2 ML Of Phenol Red
17ML Buffer (1X TBE)
Procedure:
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Fill gel box with approx. 400 ML of distilled water.
With the power supply off, connect the gel box to the power supply.
Turn the power supply on and turn the voltage knob to 150V.
Do you see any bubbles coming off the electrodes?__________
Turn the power supply off.
Add 2-3ML of Salt (Sodium Chloride- NACL). Carefully slosh the liquid in the box back and forth
to mix the salt and the water.
Turn the power supply on again to 150V.
Do you see any bubbles coming off the electrodes now?__________
What kinds of bonds does the water now contain?_____________
Why do you think bubbles might be coming off the electrodes at this point?_____________
When you turn the voltage knob down, does the rate of the bubbles decrease?____________
Turn the voltage knob up again to see if the rate of the bubbles increases.
Turn the power supply off and add 1-2ML of Phenol Red.
Carefully slosh the phenol red back and forth till the water is uniformly red.
Turn the power supply back to 150V and watch what happens to the Phenol Red.
Do you remember what phenol red is an indicator of?________
Explain what is happening to the phenol red and what is happening to the solutions at each
electrode. ____________________________________________________________
Turn the power supply off.
What is the definition of a base? An Acid? What is the Phenol Red telling us is happening at each
electrode?______________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
Add 17ML of Buffer and carefully slosh the liquid in the box back and forth to mix everything.
Turn the power supply back on to 150V.
With the buffer in the liquid do distinct colors develop now?________________
SUMMARY:
Three components of the fluid used in electrophoresis are:
___________ , _____________, and ___________
Questions:
1. Why won’t the water electrolyze by itself, before you add the salt?
2. Why are chemical reactions occurring at the electrodes after you add the salt?
3. Why does the phenol red change color and at what terminal cathode or anode?
4. Why doesn’t the phenol red change color after you add the buffer?
5. What are the two functions of the buffer tris-borate-edta (TBE)?
6. When a gel tray, with agarose gel, is added to the electrophoresis chamber, at what end should
the DNA be loaded, Cathode or Anode, and why?