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BR Biology Chapter 7 Passage 2 (#11)

Discussion in 'MCAT Study Question Q&A' started by chocposit, May 21, 2014.

  1. Can someone pleeease explain to me how the answer is yellow -> colorless? Please and thank you ~
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  3. tdod

    tdod 5+ Year Member

    Oct 30, 2011
    please repost the question.
  4. Sure thing! Hope posting images of the text are allowed (sorry BR...)

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  5. tdod

    tdod 5+ Year Member

    Oct 30, 2011
    Last edited: May 21, 2014
  6. SecondTimesTheCharm


    Apr 28, 2014
    Oxidized FAD is a conjugated molecule that absorbs light at 460 nm (Blue). Because the maximal absorption for oxidized FAD is at 460 nm, its color in solution will be complementary to the wavelength of maximal absorption. E.g. because the wavelength of maximal absorption is 460=blue, the color in solution is complementary to blue, which is yellow (Use a color wheel). The reason it goes to color less is that when FAD is reduced, it gains hydrogens and the Nitrogens convert from sp2 to sp3; which reduces the conjugation and consequently causes the molecule to no longer absorb light in the visible spectrum.
    DrknoSDN and syoung like this.
  7. Oh snap, thank you!

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