Fluorescent Proteins

Proteins like the Green Fluorescent Protein first isolated from a jellyfish fluoresce when excited by certain wavelengths of light. Fluorescence is different from luminescence or incandescence in that these two light-producing reactions use chemical energy and heat as their respective energy sources for the production of light. Fluorescence is the process of generating light when light is also used as the energy source to power the reaction. This is accomplished through a mechanism called the photoelectric effect in which the absorption of a photon of light causes an electron to jump to a higher energy state. As the photon returns to its ground state, energy is given off in the form of light at a lower energy level than that which was input into the system.