Practice question

Polyacrylamide gel formation requires initiation of vinyl polymerization. Ammonium persulfate provides free radicals by decomposing into sulfate radicals that attack the double bonds of acrylamide and bisacrylamide, starting chain growth and crosslinking into a sieving matrix. Tetramethylethylenediamine accelerates this process by catalyzing radical formation and stabilizing intermediates, but it does not generate radicals independently, thus acting as catalyst rather than initiator. Glycine serves as trailing ion in discontinuous buffer system, and Tris-HCl buffers pH. APS is therefore recognized as the true chemical initiator.