Today: Perception of color, Fluorescence, Why sky is blue Transgenic mouse glowing because of green  fluorescent  protein ...
Homework Question Thank you Michelle for the pictures with MS Paint! John B. At the time the earth experiences a solar ecl...
I’ll post some photos later on WebCT. From Veronica  http://apod.nasa.gov/apod/ap070302.html Thank you Michelle Cronoble f...
Our eye has color receptors and B/W receptors (these are sensitive photon detectors) Wikipedia Most people have  trichroma...
Let’s settle the ROYGBIV issue! Spectral colors  are colors that you see from a single frequency of light (monochromatic)…...
Demonstrations of perception of light and color <ul><li>Perception of white light </li></ul>Additive primary colors (trich...
Demos – Can you believe your eyes? <ul><li>Bidwell’s disc (this is a tricky one) </li></ul><ul><li>Color wheel and optical...
Clicker Question—Spectral colors <ul><li>Which of the following is NOT a spectral color?  Reminder: a spectral color is a ...
Clicker Question—Spectral colors <ul><li>Which of the following is NOT a spectral color?  Reminder: a spectral color is a ...
Fluorescence (1) Molecule  absorbs  a photon of a certain energy (2)  Molecule  emits  a photon of  lower energy  (nanosec...
Fluorescence (1) Molecule  absorbs  a photon of a certain energy (2)  Molecule  emits  a photon of  lower energy  (nanosec...
Phosphorescence is similar to Fluorescence, but slower <ul><li>UV Light demo…if available </li></ul>
Clicker Question—Fluorescence <ul><li>Which of the following is a possible kind of fluorescence? </li></ul><ul><li>One red...
Clicker Question—Fluorescence <ul><li>Which of the following is a possible kind of fluorescence? </li></ul><ul><li>One red...
Fluorescence is a very powerful tool in biology <ul><li>A single protein can be “labeled” fluorescently </li></ul><ul><li>...
Fluorescence Microscopy <ul><li>Filters allow blocking the excitation light (so only light comes from fluorescence) </li><...
For example, we can see proteins “absorbed” by cells <ul><li>“ Chinese Hamster Ovary” cells, up-taking quantum dots coated...
There are naturally fluorescent proteins <ul><li>GFP (“Green Fluorescent Protein”) from the jelly fish </li></ul><ul><li>O...
In addition to being absorbed, light can also be scattered
The atmosphere scatters some sunlight <ul><li>Light (an oscillation) can cause molecules to resonate </li></ul><ul><li>The...
Clicker Question—Scattering <ul><li>Which of the following is closest to the resonant frequency of a nitrogen molecule? </...
Clicker Question—Scattering <ul><li>Which of the following is closest to the resonant frequency of a nitrogen molecule? </...
So why is the sky blue?  Why are sunsets red? Lunar eclipse NASA
The blue sky and red sunsets are the same effect!
Sunset demo
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10 Feb 24 Eye, Scattering, Fluorescence, Phosphorescence Slideshare

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Human perception of color, fluorescence, applications of fluorescence in biology, why the sky is blue

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10 Feb 24 Eye, Scattering, Fluorescence, Phosphorescence Slideshare

  1. 1. Today: Perception of color, Fluorescence, Why sky is blue Transgenic mouse glowing because of green fluorescent protein from jellyfish (U. Penn)
  2. 2. Homework Question Thank you Michelle for the pictures with MS Paint! John B. At the time the earth experiences a solar eclipse, the moon observers would see a “lunar eclipse” in where the earth will be almost all light up by the sun, except for the shadow the moon would be casting in the earth. The observers would see the umbra and the penumbra created by the moon on the earth. Melody B. If we were standing on the moon during a solar eclipse we would see a small dark shadow on the Earth. This is because the moon in directly between the sun and Earth, is blocking some of the suns rays to the Earth, and is creating a small umbra with a penumbra around the umbra on the Earth. Analisa A. During a lunar eclipse the Moon people would see the Earth and that is the side of the Earth that is sleeping- the night side. There would also probably be a ring of sunlight around the Earth- like there is around the moon during a solar eclipse (as viewed on Earth). Melody A…during a lunar eclipse, when the sun fell directly behind the Earth, the Earth would look darker and there would be a thin red circle outlining the Earth, where the sunlight would be refractring through the thin atmosphere.
  3. 3. I’ll post some photos later on WebCT. From Veronica http://apod.nasa.gov/apod/ap070302.html Thank you Michelle Cronoble for the pictures with MS Paint!
  4. 4. Our eye has color receptors and B/W receptors (these are sensitive photon detectors) Wikipedia Most people have trichromatic vision color blind = dicrhomatic (still have color perception) some reports of tetrachromatic ! Key concept: the “physics of color” is really due to the anatomy and physiology of our eyes and brains Photon detector
  5. 5. Let’s settle the ROYGBIV issue! Spectral colors are colors that you see from a single frequency of light (monochromatic)…or colors that make up the spectrum e.g., magenta is NOT a spectral color Newton was a little biased in his description of ROYGBIV It actually should be ROYGCBV…cyan IS a spectral color
  6. 6. Demonstrations of perception of light and color <ul><li>Perception of white light </li></ul>Additive primary colors (trichromatic vision) (This is biology!) Subtractive primary colors Cyan, Yellow, Magenta
  7. 7. Demos – Can you believe your eyes? <ul><li>Bidwell’s disc (this is a tricky one) </li></ul><ul><li>Color wheel and optical discs </li></ul>
  8. 8. Clicker Question—Spectral colors <ul><li>Which of the following is NOT a spectral color? Reminder: a spectral color is a “pure” color that can be created by a single frequency of light. </li></ul><ul><li>Magenta </li></ul><ul><li>Cyan </li></ul><ul><li>Yellow </li></ul><ul><li>Blue </li></ul><ul><li>Green </li></ul>
  9. 9. Clicker Question—Spectral colors <ul><li>Which of the following is NOT a spectral color? Reminder: a spectral color is a “pure” color that can be created by a single frequency of light. </li></ul><ul><li>Magenta is a mixture of blue and red </li></ul><ul><li>Cyan </li></ul><ul><li>Yellow </li></ul><ul><li>Blue </li></ul><ul><li>Green </li></ul>These CAN be created by mixtures, but also are spectral colors
  10. 10. Fluorescence (1) Molecule absorbs a photon of a certain energy (2) Molecule emits a photon of lower energy (nanoseconds delay)
  11. 11. Fluorescence (1) Molecule absorbs a photon of a certain energy (2) Molecule emits a photon of lower energy (nanoseconds delay) UV Light
  12. 12. Phosphorescence is similar to Fluorescence, but slower <ul><li>UV Light demo…if available </li></ul>
  13. 13. Clicker Question—Fluorescence <ul><li>Which of the following is a possible kind of fluorescence? </li></ul><ul><li>One red photon absorbed, one green emitted </li></ul><ul><li>One red photon absorbed, one blue emitted </li></ul><ul><li>One infrared photon absorbed, one blue emitted </li></ul><ul><li>One ultraviolet photon absorbed, one blue emitted </li></ul><ul><li>One blue photon absorbed, one ultraviolet emitted </li></ul>
  14. 14. Clicker Question—Fluorescence <ul><li>Which of the following is a possible kind of fluorescence? </li></ul><ul><li>One red photon absorbed, one green emitted </li></ul><ul><li>One red photon absorbed, one blue emitted </li></ul><ul><li>One infrared photon absorbed, one blue emitted </li></ul><ul><li>One ultraviolet photon absorbed, one blue emitted </li></ul><ul><li>One blue photon absorbed, one ultraviolet emitted </li></ul>Conservation of energy! High energy photon absorbed, lower energy emitted.
  15. 15. Fluorescence is a very powerful tool in biology <ul><li>A single protein can be “labeled” fluorescently </li></ul><ul><li>Different colors can label different proteins </li></ul>“ Quantum dots” of various colors Lung epithelial cells (DNA blue, cilia red)
  16. 16. Fluorescence Microscopy <ul><li>Filters allow blocking the excitation light (so only light comes from fluorescence) </li></ul>
  17. 17. For example, we can see proteins “absorbed” by cells <ul><li>“ Chinese Hamster Ovary” cells, up-taking quantum dots coated with protein </li></ul><ul><li>Diane Lidke, UNM HSC </li></ul>
  18. 18. There are naturally fluorescent proteins <ul><li>GFP (“Green Fluorescent Protein”) from the jelly fish </li></ul><ul><li>Osamu Shimomura and Roger Y. Tsien—2008 Nobel Prize, Chemistry </li></ul><ul><li>Scientists know how to add GFP to the genome of a cell </li></ul><ul><ul><li>-> ANY protein can be made to glow green! </li></ul></ul>GFP Mouse!
  19. 19. In addition to being absorbed, light can also be scattered
  20. 20. The atmosphere scatters some sunlight <ul><li>Light (an oscillation) can cause molecules to resonate </li></ul><ul><li>The closer to the resonant frequency, the more scattering (Imagine the “resonant square” demo…or acoustic resonance) </li></ul><ul><li>Visible light is below the “resonant” frequncey of Nitrogen </li></ul>
  21. 21. Clicker Question—Scattering <ul><li>Which of the following is closest to the resonant frequency of a nitrogen molecule? </li></ul><ul><li>Red light </li></ul><ul><li>Blue light </li></ul><ul><li>Green light </li></ul>
  22. 22. Clicker Question—Scattering <ul><li>Which of the following is closest to the resonant frequency of a nitrogen molecule? </li></ul><ul><li>Red light </li></ul><ul><li>Blue light </li></ul><ul><li>Green light </li></ul>The intensity of light waves scattered by the atmosphere is higher at higher frequencies Intensity  (frequency) 4
  23. 23. So why is the sky blue? Why are sunsets red? Lunar eclipse NASA
  24. 24. The blue sky and red sunsets are the same effect!
  25. 25. Sunset demo

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