DNA Detective: Reuniting Families with DNA Fingerprinting and Electrophoresis
Introduction to Micropipetting
PRACTICE using the pipette! (For this step, you will need to obtain a test strip and red dye before starting.) 1. PRACTICE ADJUSTING the volume. Use your free hand to TURN the volume-setting wheel clockwise to increase the volume and counter clockwise to de - crease the volume (see NOTE 1). OBSERVE the volume display (see NOTE 2). Remember to always stay within the volume range of the pipette. 2. PLACE a new tip on your pipette. 3. SET the volume to 5 µL. 4. With your free hand PICK UP the test tube. HOLD the tube between your thumb and forefinger and at or near eye level to best observe the liquid moving into the pipette during the next few steps. 5. PRESS the plunger down to the first soft stop and HOLD it in this position. 6. DIP the tip into the solution. Immerse the tip enough to cover the end but not so deep that it obscure your view of the liquid ~ 5 mm. 7. Keeping the tip in the solution, slowly RELEASE the plunger until it is in its original position. You should see the liquid flowing into the pipette tip (see NOTE 3).
NOTE 1: If the volume-setting wheel is not moving, it may be that your pipette is locked at a certain volume. In many pipettes the volume lock is a small button that is located just below the tip ejector. This button can be disengaged by pushing upwards and re-locked by pushing downwards. NOTE 2: Most pipettes have vol- ume displays that are read top down. Some volume displays will contain a white dash line represent - ing the decimal point. Account for this decimal place when setting your Watch out for bubbles in the tip or air space at the end of the tip. These can significantly offset the measurement! If you observe either, expel the liquid back into the tube (Steps 9-12) and then repeat the process start- ing at Step 4. Often air is introduced when pipetting quickly so perform these steps slowly. volume! NOTE 3:
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