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How and why do fireflies light up?
Scientific American
Marc Branham
9/5/2005
Excerpt:
Marc Branham, an assistant professor in the department of entomology and nematology at the University of Florida, explains.
Fireflies produce a chemical reaction inside their bodies that allows them to light up. This type of light production is called bioluminescence. The method by which fireflies produce light is perhaps the best known example of bioluminescence. When oxygen combines with calcium, adenosine triphosphate (ATP) and the chemical luciferin in the presence of luciferase, a bioluminescent enzyme, light is produced. Unlike a light bulb, which produces a lot of heat in addition to light, a firefly's light is 'cold light', without a lot of energy being lost as heat. This is necessary because if a firefly's light-producing organ got as hot as a light bulb, the firefly would not survive the experience.
A firefly controls the beginning and end of the chemical reaction, and thus the start and stop of its light emission, by adding oxygen to the other chemicals needed to produce light. This happens in the insect's light organ. When oxygen is available, the light organ lights up, and when it is not available, the light goes out. Insects do not have lungs, but instead transport oxygen from outside the body to the interior cells within through a complex series of successively smaller tubes known as tracheoles. For a long time it was a mystery as to how some firefly species manage such a high flash rate, considering the relatively slow speed of the muscles that control oxygen transport. Researchers fairly recently learned that nitric oxide gas (the same gas that is produced by taking the drug Viagra) plays a critical role in firefly flash control. In short, when the firefly light is żoff," no nitric oxide is being produced. In this situation, oxygen that enters the light organ is bound to the surface of the cell's energy-producing organelles, called the mitrochondria, and is thereby not available for transport further within the light organ. The presence of nitric oxide, which binds to the mitochondria, allows oxygen to flow into the light organ where it combines with the other chemicals needed to produce the bioluminescent reaction. Because nitric oxide breaks down very quickly, as soon as the chemical is no longer being produced, the oxygen molecules are again trapped by the mitochondria and are not available for the production of light.
..........................................
View the complete article at:
http://www.scientificamerican.com/ar...-do-fireflies/
Scientific American
Marc Branham
9/5/2005
Excerpt:
Marc Branham, an assistant professor in the department of entomology and nematology at the University of Florida, explains.
Fireflies produce a chemical reaction inside their bodies that allows them to light up. This type of light production is called bioluminescence. The method by which fireflies produce light is perhaps the best known example of bioluminescence. When oxygen combines with calcium, adenosine triphosphate (ATP) and the chemical luciferin in the presence of luciferase, a bioluminescent enzyme, light is produced. Unlike a light bulb, which produces a lot of heat in addition to light, a firefly's light is 'cold light', without a lot of energy being lost as heat. This is necessary because if a firefly's light-producing organ got as hot as a light bulb, the firefly would not survive the experience.
A firefly controls the beginning and end of the chemical reaction, and thus the start and stop of its light emission, by adding oxygen to the other chemicals needed to produce light. This happens in the insect's light organ. When oxygen is available, the light organ lights up, and when it is not available, the light goes out. Insects do not have lungs, but instead transport oxygen from outside the body to the interior cells within through a complex series of successively smaller tubes known as tracheoles. For a long time it was a mystery as to how some firefly species manage such a high flash rate, considering the relatively slow speed of the muscles that control oxygen transport. Researchers fairly recently learned that nitric oxide gas (the same gas that is produced by taking the drug Viagra) plays a critical role in firefly flash control. In short, when the firefly light is żoff," no nitric oxide is being produced. In this situation, oxygen that enters the light organ is bound to the surface of the cell's energy-producing organelles, called the mitrochondria, and is thereby not available for transport further within the light organ. The presence of nitric oxide, which binds to the mitochondria, allows oxygen to flow into the light organ where it combines with the other chemicals needed to produce the bioluminescent reaction. Because nitric oxide breaks down very quickly, as soon as the chemical is no longer being produced, the oxygen molecules are again trapped by the mitochondria and are not available for the production of light.
..........................................
View the complete article at:
http://www.scientificamerican.com/ar...-do-fireflies/
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