Credit: Image courtesy of Nobel Foundation
The green fluorescent protein GFP consists of 238 amino acids, linked together in a long chain. This chain folds up into the shape of a beer can. Inside the beer can structure the amino acids 65, 66 and 67 form the chemical group that absorbs UV and blue light, and fluoresces green.
Soooo Über Cool - Chemistry! It won the Nobel Prize 2008. :-)