Exercise 4.5 - Documentation


Figure 4.8 Silver stained protein gel



  1. Photograph the gels.

  2. Use the photographs or negatives to measure the distance from the point of protein application (or for two gel systems, the line separating the stacking and separating gels) to the final location of the tracking dye near the bottom of the gel. 16

  3. Measure the distance from the point of origin to the center of each band appearing on the gel.

  4. Divide each of the values obtained in Step 3 by that obtained in Step 2 to obtain the relative mobility (the Rf value) for each band.

  5. Using either the graph of Rf values and molecular weights from Exercise 4.2, or Figure 4.8, compute the molecular weights of each band.


Scan the negative with a densitometer and compute Rf values based on the distances from the point of origin to the peak tracing for each protein band. Integration of the area of each peak will yield quantitative data as well as the molecular weight.

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Cell Biology Laboratory Manual
Dr. William H. Heidcamp, Biology Department, Gustavus Adolphus College,
St. Peter, MN 56082 -- cellab@gac.edu