Scientists today have the ability to modify the genetic makeup of plants and animals, and even to transfer genes from one species to another. Not since nuclear power has a technology been so controversial, with opponents concerned about the creation of so-called Frankenfoods and proponents promising a better tomorrow through science. The term genetically modified organism (GMO) is used to refer to any microorganism, plant, or animal in which genetic engineering techniques have been used to introduce, remove, or modify specific parts of its genome. Examples include plants being modified for pest resistance; lab animals being manipulated to exhibit human diseases, such as sickle cell anemia; and even glowing jellyfish genes inserted in a rabbit for an art piece. GMOs show great promise in improving agriculture. Plants could be engineered to better tolerate temperature or weather extremes, to contain various vitamins, or to dispense medicines and vaccines. Many think genetically modified foods have the potential to end world hunger. On the other hand, there are fears that the disease- or pest-resistant genes inserted into crop plants might escape into other plants, creating hard-to-control superweeds. There is also the possibility of unexpected effects on other flora and fauna, the risk of agriculture being controlled by biotech companies, and, as with any new technology, problems that are yet unknown.