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Activity Sheet
Techniques Lab B: Electrolysis and Electrophoresis

Name_______________________________________

Date__________       Period_______

PRELAB:
Check with your teacher.


OBSERVATIONS:



  1. Label the above illustration of the power supply and gel boxes. Don't forget to label the positive and negative connections (D, E, K, and M)



  2. Draw lines representing electrical leads to show how the gel boxes should be connected to the power supply.



  3. Explain in words how you knew where to connect the electrical leads (question # 2):



    As you move through the procedure record your observations here.

    STEP GEL BOX CONTENTS POTENTIAL
    (volts)
    CURRENT
    (milliamps)
    OTHER OBSERVATIONS
    (color changes, bubbles, etc.)
    3 Empty gel box
    (air only inside)
    100 V                                      
    5 Distilled water
     
    100 V                                      
    7 Distilled H2O + NaCl
     
    100 V                                      
    10 Distilled H2O + NaCl
    + phenol red
    100 V                                      
    13 Distilled H2O + NaCl
    + phenol red + buffer
    100 V                                      


  4. Use the graph below to plot the information in steps 3, 5, 7, 10, and 13 as a bar graph.


        Current   
     
        (in milliamps)    
                                                                                                                           
                                           
                                           
                                           
                                           
                                           
                                           
                                           
                                           
                                           
                                           


  5. Summarize in your own words the effects of sodium chloride, phenol red and buffer on current.



















    Record data from Steps 7 (again) and 8 in the table below.

    STEP GEL BOX CONTENTS POTENTIAL
    (volts)
    CURRENT
    (milliamps)
    OTHER OBSERVATIONS
    (color changes, bubbles, etc.)
    7 Distilled H2O + NaCl 100 V                                      
    8 Distilled H2O + NaCl                                        
    8 Distilled H2O + NaCl                                        
    8 Distilled H2O + NaCl                                        


  6. Use the graph below to plot the information in Steps 7 and 8.

        Current   
     
        (in milliamps)    
                                                                                                                           
                                           
                                           
                                           
                                           
                                           
                                           
                                           
                                           
                                           
                                           
    Potential (in volts)


  7. Summarize in your own words the relationship between potential and current.






  8. When and where were gases produced?



  9. What was the source of the gases you observed?







  10. What did the color change in phenol red indicate about the pH in the gel box when you had salt water in the box?



  11. What effect did adding the buffer have on the initial color of phenol red and on the subsequent changing of the color?



  12. What effect does the buffer have on the pH of a solution?



  13. Why might salt and buffer be necessary components of the electrophoresis buffer , which you will use to electrophoresis DNA?





  14. Does the liquid in the gel box become more acidic or basic at the anode? How can you tell?







Alternate Diagram of Power Supply (Fotodyne FotoForce 150)













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