 When run on the gel with a temperature gradient, only one band will appear.If the target DNA has a distinct allele, four products will form following the reannealing step; homoduplexes consisting of target DNA, homoduplexes consisting of normal DNA and two heterduplexes of each strand of target DNA hybridized with the normal DNA strand.These four products will have distinct melting temperatures and will appear as four bands in the denaturing gel.