How firefly emits light?
How firefly
emits light?
PROF
WAQAR HUSSAIN
Fire flies are winged beetles of
insect family, comprising of 2000 species. Fire flies are also known as glow
worm and light bug because they produce cold light of wavelength 510 to 670
nanometers. Light is produced due to a process called bioluminescence occurring
in the cells of its lower abdomen with the help of a chemical luciferin(light
bearer) which under goes enzyme catalyzed oxidation and an “intermediate” is
formed in excited state that when returns to ground state, emits light. This
light emitting process proceeds in two reactions:
First,
luciferin combines with adenosine triphosphate(ATP) to form luciferyl adenylate
and pyrophosphate(PPi) in the presence of magnesium ions on the surface of
enzyme luciferase.
(1) Luciferin + ATP
Luciferyl adenylate + PPi
Second,
luciferyl adenylate combines with oxygen to form oxyluciferin and
adenomonophosphate(AMP) and light is produced.
(2) Luciferyl
adenylate + O2
Oxyluciferin +AMP+Light
The light producing cells also have crystal
of uric acid which reflects the light away from the abdomen. Fire flies have no
lungs thus oxygen is supplied. through special tubes called trachea. The switching
of light on and off is controlled by nerve cells or oxygen supply.
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