Fluorescence Resonance Energy Transfer (FRET): A physical phenomenon where energy is transferred between two fluorophores, typically molecules that can fluoresce, due to their proximity and spectral overlap. FRET occurs when the emission spectrum of the donor fluorophore overlaps with the absorption spectrum of the acceptor fluorophore. When the donor fluorophore is excited and fluoresces, it can transfer energy non-radiatively to the acceptor fluorophore, causing it to emit fluorescence as well. FRET is widely used in molecular and cellular biology to study molecular interactions, such as protein-protein interactions or conformational changes, by monitoring changes in fluorescence intensity or lifetime between the donor and acceptor fluorophores.
