The steps for measuring fragments are all on this screen, so scroll down to see all of them.
Assume that T7 phage DNA has been digested with the enzyme NruI (lane 2), BclI (lane 3), and both NruI and BclI (lane 1), as was done earlier in this tutorial in the section on restriction mapping. This same example will now be used to demonstrate some general features of gel electrophoresis in this simulation.
| Note: Although DNA fragments are used as examples below, the same procedures can be use to see the migration distances and molecular weights (in daltons) for proteins. Units given for distance are arbitrary, but for DNA each unit would approximately equal 1 millimeter (100 millimeters total width). |
1. By default, the migration distances for the first lane are automatically given each time a gel is run. To see migration distances for a different lane, either click on the lane itself...
... or use the 'Data'' button (bottom right below) to select a lane.
2. To see the sizes of fragments in a lane, use the 'Data' menu, select 'Sizes', and select a lane as shown below...
...and the sizes for the first lane appear, measured in kilobases (1000 base pairs).
3. Another way to see the size or distance of an individual fragment is to click on it. Depending upon whether you have selected 'Sizes' or 'Distance' using the 'Data' button, the appropriate value will be outlined in red in the data grid, as shown below. In addition, the size for that fragment will appear in the bottom field (5040 base pairs or 5.040 kilobases in this example).
4. Clicking on the 'Sequence' box (on gray bar) shows the DNA sequence for this particular fragment (this also works for protein fragments). Click here to go back to the "other features" menu, or else click the "Next" button to see the next feature.
