Figure 3.

(Lower) Dependencies of inverse mobilities on DNA length observed for electrophoresis in gels of (A) 20% Pluronic, (B) 5% polyacrylamide, and (C) 2% agarose. Open circles (○) represent Nx123 bp ladder fragments, and filled circles (•) represent pGEM fragments. Mobilities were normalized to the mobility of the 123-bp fragment. Solid lines for polyacrylamide and agarose gels in frames B and C are linear least-squares fits to all points. Solid line for Pluronic gel in A is a best-fit third order polynomial to data for the Nx123 bp fragments only. R² ≥ 0.999 for all fits. (Upper) Errors (%) in the lengths estimated for Nx123 bp fragments (○) and pGEM fragments (•). Mobilities of the Nx123 ladder fragments only were least-squares fit to straight lines (2% agarose, 5% polyacrylamide) or a third-order polynomial (20% Pluronic). Best-fit equations (R² ≥ 0.999) were used to calculate estimated lengths of the pGEM and Nx123 fragments from mobilities.