Sources of Light - PowerPoint by 282REF

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									                  Bioluminscence
    Greek bios = living          Latin lumen = light
   the production and emission of light by a living
    organism as the result of a chemical reaction between
    two different chemicals during which chemical energy is
    converted to light energy.
   Most of the world's bioluminescence exists in the
    ocean. Of the marine animal phyla, 14 have members
    that produce light, more than half of all animal phyla
    capable of bioluminescence.
   Bioluminescent life forms live mostly in the twilight or
    disphotic zone – the poorly lit part of the ocean.
                 Natural Bioluminescence
                   Cells contain a chemical called luciferin and make an
                      enzyme called luciferase.
                   To make light, the luciferin combines with oxygen to form
                      an inactive molecule called oxyluciferin.
                   The luciferase speeds up the reaction, which occurs in two
                      steps:


        1. luciferin + ATP -------------> luciferyl adenylate + PPi

        1. luciferyl adenylate + O2 -------------> oxyluciferin +AMP +
           light

The cells that make the light have uric acid crystals that help reflect the light
away from the abdomen. The oxygen is supplied to the cells through a tube in
the abdomen called the abdominal trachea. It is not known whether the on-off
switching of the light is controlled by nerve cells or the oxygen supply.
            Uses for Bioluminscence
   Communication: Fireflies flash at one another in a species-specific pattern, often to
    find a mate.
   Locating food: In the depths of the ocean, some fish species use their light like a
    spotlight to find prey.
   Attracting prey: Some species, like the angler fish, use a luminescent lure to attract
    other fish.
   Camouflage: In the darker parts of the ocean, it's hard to see anything below you, but
    it's easy to see the silhouette of what's above you. For this reason, some species
    produce spots of light on their undersides, which blur their outlines and allow them to
    blend in with the light from above. This is also known as counter-illumination.
   Mimicry: The cookie-cutter shark has one unlit patch on its underside, which
    resembles a smaller fish when viewed from below. When a large predator approaches,
    the shark can take a large bite and then flee. This allows the cookie-cutter shark to prey
    on animals that are much larger and more powerful than itself.
   Self-defense: When threatened, some animals release a cloud of bioluminescent fluid,
    similar to the way squid defend themselves with a cloud of ink. Others use a bright
    flash to blind predators.
                          Found in:
   Marine Vertebrates
   Marine Invertebrates
   Microorganisms
   Terrestrial Animals
   Symbiotic organisms within larger
    organisms
hydromedusa Aequorea victoria is probably the most
   influential bioluminescent marine organism.




                      Remember Transgenic
                      Organisms???!!
      FLUORESCENCE – as in bulbs
   There is a stream of electrons flowing between the electrodes at both
    ends of the fluorescent bulb.
   The electrons interact with mercury vapour atoms floating inside the
    bulb.
   The mercury atoms become excited, and when they return to an
    unexcited state they release photons of light in the ultraviolet region of
    the spectrum.
   These ultraviolet photons collide with the phosphor coating the inside of
    the bulb, and the phosphor creates visible light.
   The phosphor fluoresces to produce light. A fluorescent bulb produces
    less heat, so it is much more efficient. A fluorescent bulb can produce
    between 50 and 100 lumens per watt. This makes fluorescent bulbs
    four to six times more efficient than incandescent bulbs. That's why
    you can buy a 15-watt fluorescent bulb that produces the same amount
    of light as a 60-watt incandescent bulb.
            Flourescence
   There is a chemical in
    the shell of the scorpion
    that makes it glow under
    long wavelength UV
    light.
   Baby scorpions do not
    glow.
     Phosphorescence
   Glow in the dark stickers
    The excited product is more
    stable, so that the time until
    the energy is released is much
    longer, resulting in a glow long
    after the light has been shut
    off.
                   Chemiluminesence
1.   The hydrogen peroxide oxidizes
     the phenyl oxalate ester, resulting
     in a chemical called phenol and an
     unstable peroxyacid ester.
2.   The unstable peroxyacid ester
     decomposes, resulting in
     additional phenol and a cyclic
     peroxy compound.
3.   The cyclic peroxy compound
     decomposes to carbon dioxide.
4.   This decomposition releases
     energy to the dye.
5.   The electrons in the dye atoms
     jump to a higher level, then fall
     back down, releasing energy in
                  light.
     the form of light.
              Triboluminescence
   Occurs when molecules (crystalline sugars) are crushed,
    forcing electrons out of their atomic fields. Free
    electrons bump into nitrogen molecules in the air.
    When they collide, the electrons impart energy to the
    nitrogen molecules, causing them to vibrate. In this
    excited state, and in order to get rid of the excess
    energy, these nitrogen molecules emit light.
Triboluminescence



             Are You Ready
               For Some
                 Fun?!


        methyl salicylate
                   How it works…
1.   When you shatter the sugar crystals with your teeth,
     electrons (which are negatively charged) break free. As a
     result, the atoms in which the electrons were formerly
     embedded become positively charged.
2.   As the sugar crystals disintegrate, nitrogen molecules from
     the air attach themselves to the fractured surfaces. When
     the free electrons strike the nitrogen molecules, they cause
     the latter to emit invisible ultraviolet radiation, along with a
     faint visible glow.
3.   The UV radiation is absorbed by the wintergreen flavoring,
     methyl salicylate, which is fluorescent. This then emits the
     fairly bright blue light you see.

								
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