Thermal or Temperature Gradient Gel Electrophoresis (TGGE) is a variant of gel electrophoresis that detects single nucleotide changes, or small insertions or deletions, in DNA. The duplex DNA, usually between 100 and 300 nucleotides long and generated by the polymerase chain reaction (PCR), is forced through a gel that contains an increasing temperature gradient. TGGE is essentially the same technique as Denaturing Gradient Gel Electrophoresis (DGGE) where, instead of a temperature gradient, a chemical gradient is used. Although TGGE requires more specialist equipment, it is often preferred by scientists because the chemicals used in DGGE are toxic. As the DNA moves through the gel, it encounters a temperature, which makes the duplex melt, or denature. This denatured DNA is essentially arrested at that point in the gel, and forms a sharp band. The point at which the DNA duplex denatures can be affected by...