concept

Green fluorescent protein (GFP)

A protein taken from the crystal jellyfish *Aequorea victoria* that absorbs blue light and re-emits it as green. In the jellyfish it receives energy from the light-making reaction and shifts that light to green. Plucked out and wired into other organisms as a glowing tag, GFP revolutionized biology - letting researchers light up a single gene switching on inside a living cell. Work on GFP won the 2008 Nobel Prize in Chemistry. Note: GFP is fluorescence (it needs incoming light), distinct from bioluminescence (which makes its own).