DNA pellet - (Sep/17/2012 )
D ear all,
Anyone here that can tell me where I can find a good explenation on why clean/pure DNA pellets are invisible while the dirtier ones are the visible ones?
I know this is true, but cant find a good literature source for this.
I know its on wiki , but I am trying to find some good reasons, explenations for this or perhaps some paper on this.
Well a good question, and actually I have no real idea (and physics exams are long ago )..
wikipedia says: "White light reflected off objects can be seen when no part of the light spectrum is reflected significantly more than any other and the reflecting material has a degree of diffusion. People see this when transparent fibers, particles, or droplets are in a transparent matrix of a substantially different refractive index."
If you remember that the white pellet is a mixture of DNA and several different proteins (and other stuff such as salts, sugars...) and these have a different refractive index, because several types of proteins and salts are involved that surely influence how light passes through the pellet differently, this might be an explanation (don't forget that we perceive it as white, so it's a subjective perception and not more).
But perhaps someone else has a better explanation.
I have not yet found a better explanation.