Bioluminescence

Bioluminescence BIO means LIFE Luminescence means LIGHT Can you guess what Bioluminescence means?? Bioluminescence is defined as the production and the emission of light by a living organism.

Chemical Reaction Bioluminescence occurs when an electron receives sufficient energy from an external source to drive the electron an excited higher energy state. At this point, the system is unstable. When the electron returns to the lower state, energy is given off in the form of a photon.

Chemical Reaction Three requirements for reaction to proceed: Light emitting organic molecule – Typically Luciferin 2) Source of Oxygen 3) Protein Catalyst – Typically Luciferase

Photoproteins Sometimes the three required components for biolumenescence are bound together into a complex called a Photoprotein. Photoproteins are not involved in luciferin-luciferase reaction. Instead photoproteins utilizes an organic light emitting molecule and a cofactor. The total amount of light emitted is porportional to the size of the photoproein

Photoproteins The jellyfish, Aequorea, uses a photoprotein. Instead of a protein catalyst, the jellyfish emits light when the cofactor Ca2+ is introduced into the system.

Fluorescent Proteins Sometimes, there is a fluorescent protein that absorbs the light and remits the light at longer wavelengths. Examples include Green Fluorescent Proteins and Phycobiliproteins.

Green Fluorescent Proteins Amino acids in the 66th and 67th position emit fluorescence of wavelengths around 510 nm The GFP gene is used in research to track activity at the cellular level.

Phycobiliproteins Phycobiliproteins occur naturally in algae and bacteria and contain a covalently linked fluorescence group The wavelength of light emitted from these proteins is between 575nm and 660nm

Examples in Nature Diatoms are marine phytoplankton that emit blue-green fluorescence. That creates the “glowing” blue waves below. These diatoms are actually used in street paint for the glowing properties.

Examples in Nature While terrestrial biolumenescence is less common, they do still exist. Examples include fireflies and a type of fungus called foxfire.