Practice question

The running buffer in agarose electrophoresis, typically TAE or TBE, fulfills multiple physicochemical roles. It provides conductivity for current flow, maintains pH around 8.0 to 8.5 to ensure DNA remains fully deprotonated and negatively charged, and supplies counterions that establish electric field uniformity. Tris buffers protons, while EDTA chelates divalent cations, inhibiting nucleases. Maintaining constant pH prevents alterations in charge or band distortion. It does not increase sample volume, fix DNA, or stain proteins. Thus pH and ionic strength maintenance are its principal functions.