I have done a couple of DNA separations and observe that the clumped strands of DNA are white.

Is that an artifact of the chemicals used in standard separations? Or is it indeed the case that the DNA molecule in standard conditions does not absorb many or any photons in the visual range?

If that is right, can we use this as evidence for why visible spectrum light doesn't cause mutations, unlike say higher energy photons in the UV range?

Looking forward to your thoughts.

  • $\begingroup$ The reason why visible light doesn't cause mutations are simply because it has not enough energy. For this reason it doesn't penetrate far enough into the skin and has not enough energy to do the damage. DNA itself is not white, this is only because it is clumped together and reflects the light. $\endgroup$ – Chris Feb 23 '16 at 9:30
  • $\begingroup$ Thanks @Chris. Even in theory, can a visible spectrum photon cause a mutation? $\endgroup$ – Simon S Feb 23 '16 at 9:32
  • 1
    $\begingroup$ @SimonS Some chemicals can be photo-excited to form reactive intermediates and these in-turn can damage the DNA. Visible light per se cannot do any damage. $\endgroup$ – WYSIWYG Feb 23 '16 at 9:58

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