Scorpion primers are similar to Molecular Beacons™, but they contain a PCR primer sequence. When the target DNA is amplified during PCR, the beacon fragment binds to the newly synthesized DNA, and thus, separates the fluorophore from the quencher. To prevent the stem-loop structure from being copied during PCR, a “PCR blocker” is also incorporated in the hairpin. The intra-molecular binding between the scorpion primer and the downstream PCR product is kinetically more favorable than that of Molecular Beacons and TaqMan probes. Unlike the TaqMan and Molecular Beacons, the Scorpion system do not require a separate probe and hence, gives a larger fluorescent signal.