Page 26 - An Identity Crisis

6. Place the tip of the pipette into the liquid in 2. Before turning on the power supply, ensure the
the tube, but do not touch the bottom. Slowly supply reads “Volts” and the setting is “Low.”
release the plunger to obtain the contents of 3. Once all lab stations have been checked, turn
the tube.
on the power supply and twist the knob until
7. Carefully suspend the tip in the appropriate the display reads the voltage suggested by your
well in the gel, being careful not to touch the gel instructor (usually between 60 and 100 volts).
itself.
4. Within a few minutes the orange dye should be
8. Press the plunger down slowly to dispense observed to have moved out of the wells. If the
the sample into the well. Do not touch the gel dye remains in the wells ensure that your power
itself. Remove the pipette from the well before supply is plugged in, is turned on, and is set to
releasing the plunger. the correct voltage. If problems persist after
several minutes more, alert your instructor.
9. Discard the used tip.
5. As the gel runs, DNA will be visible migrating
10. Record the location of the sample on your data through the gel. It will begin as a faint blue
collection sheet.
streak near the wells.
11. Moving from left to right, repeat these steps 6. After the gel has run for a time, the blue bands will
for each sample, using a different well and tip have separated and grown darker. The blue color
each time.
will intensify as the DNA stains while the gel runs.
The DNA will never become strongly contrasted

RUNNING THE GEL (45 MIN) against the gel, but should be clearly visible.
7. Allow the gel to run until the orange color in the
1. Place the lid down on the top of the gel box. loading dye has migrated about 75% of the way
Ensure that the black electrode matches up through the gel.
with the black lead and red with red. Plug the
leads into the power supply, also matching the 8. Promptly record the positions of the DNA on the
colors. gel on your data collection sheet.

26 THE MYSTERY OF LYLE AND LOUISE