Fluorescein amidite

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Fluorescein amidite, abbreviated FAM, is an important dye used in molecular biology. It is often used in creation probes to detect the presence of specific nucleic acid sequences. A primer can be modified at one end with a FAM and at the other end with a quencher. The primer is designed such that its native state is a hairpin, allowing the quencher to change the light emitted from the Fluorescein into heat. Upon denaturation, usually through annealing to a complementary sequence, the quencher is separated from the Fluorescein molecule, allowing it to emit light, which is detected. The amount of light detected is directly proportional to the concentration of nucleic acid complementary to the primer in solution.