the 1993 film "jurassic park" (based on the 1990 michael crichton novel of the same name) features dinosaurs that were genetically altered so that they could not produce the amino acid lysine. this was known as the "lysine contingency" and was supposed to prevent the cloned dinosaurs from surviving outside the park, forcing them to be dependent on lysine supplements provided by the park's veterinary staff. in reality, no animals are capable of producing lysine (it is an essential amino acid).