Exercise 2 – Practice using pipettes to load wells
Loading DNA samples into the tiny wells of a thin gel is a delicate operation and requires practice. If a well is punctured by the pipette, the sample will drain out and be lost. In the Central Study Area obtain a petri dish filled with agar and containing a series of wells – the practice pipetting station. You will also need a small sample tube of loading dye. At your carrel you will find a micropipetter and a box of pipette tips. Put a new tip on your micropipetter and open the tube of loading dye. Press down on the plunger on the top of the pipetter, let it rise slowly as you draw up the dye. Once the practice loading dye has been drawn into the micropipette tip, carefully introduce the tip to the end of a well pointing towards the middle of the well itself. Position the tip so that it just enters the opening of the well. Be careful not to push the tip into the bottom of the well. Slowly expel the practice loading dye. When expelled slowly, the sample will sink into the well even if the tip is not actually in the well but above it. You and your group should take turns loading the wells in the petridish, so that you will be ready to load the gel for the DNA analysis. Show your practice plate to a lab instructor. You must show your practice wells to your TA to get the DNA for Exercise 3.