Loading gels is a necessary skill in molecular
biology. The first step is checking the sample before loading, as shown
below:
| After loading sample into the pipette tip, check
carefully for bubbles. Make sure that there is no air at the end of the
tip. This can create bubbles which might "puff" the DNA out of the well.
The sample is blue because of the loading/tracking dye mixed in with the DNA solution. This helps us see the solution when loading into the gel, and also helps follow the progress of the gel as it is run. |
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When loading a gel, support the hand holding the pipettor and help guide the tip into the well. This will help keep the tip steady. This series of three photos show the process of loading a sample into a gel well:
| The pipette tip is placed into the buffer and above
the gel well.
Do not put the tip too deeply into the gel well because you can puncture through the well and the sample will leak out |
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| The sample is ejected smoothly into the well.
The pipette plunger is pushed down until the stop is reached. Do NOT push past the stop because you will create a bubble. Do NOT release the plunger until the tip is out of the gel. |
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| Once the tip has been removed from the gel, then
the plunger can be released.
Notice that only a small amount of sample remains in the tip, not enough to matter. |
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| As this figure shows, the pipette tip is held over the well, with the tip submerged in the buffer layer. |  |
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| Running an agarose gel.
ABOVE is a minigel apparatus and BELOW is a midigel apparatus. Note the condensation on the lid from the heat of the current. |
The gel appartus with the lid removed and the power
off, showing the gel.
ABOVE is the minigel and BELOW is the midigel. These gels have run long enough to separate the two dye bands. |
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