Submitted by Picture-unrelated t3_xtlcoz in science
VoraciousTrees t1_iqrpjmf wrote
So... Melanin grants resistance to ionizing radiation?
ubermeisters t1_iqs3xrw wrote
every little bit helps when it comes to reflecting or diffusing electromagnetic radiation
asenz t1_iqsn3jl wrote
I thought white color reflects all frequencies while black color absorbs all frequencies. Why does nature use black color then?
Ghost33313 t1_iqsr0mf wrote
Different part of the electromagnetic spectrum I would assume. Not like we see radiation.
lostinsoup t1_iqt99gf wrote
While It’s true we can’t see ionizing radiation, we can see radiation, we call it “visible light.”
burningcpuwastaken t1_iqth47k wrote
Ah, but you want it to absorb the light. This allows the energy to be dissipated as heat to surrounding tissue. An alternative is DNA absorbing the energy and breaking apart / being damaged.
SeekingTheTruth t1_iqtia4n wrote
This. In fact the melanin protects primarily the DNA and not the whole cell.
Hedge89 t1_iqtluri wrote
Gamma radiation, the form of ionising radiation that's an electromagnetic wave, is so small it doesn't really reflect off things, it'll pass straight through a mirror for instance, or y'know, a thin sheet of lead. Better to block it by giving it something harmless that can intercept it and get ionised that's not DNA. Though in this case it appears that it's more that melanin can mop up free radicals and reduce DNA damage that way. Basically, you can't realistically block gamma radiation with frog skin, but you can stuff it full of compounds that mop up the damaging byproduct of being hit with it.
ubermeisters t1_iqsric3 wrote
Same reason the greater majority of stealth craft are all black. Sometimes its more about just redirecting radiation, rather than purely reflecting or absorbing.
bobskizzle t1_iqug07m wrote
The molecules that make up most white things usually aren't able to screen (what a metal does) or significantly absorb light with energies high enough to be damaging to DNA. What you see as white is usually only good at scattering most might in a relatively narrow band of visible light, and since scattering doesn't change the angle of the main energy path much, it's not really protective (you'll get a chain of scattering off of lots of molecules as the photon dumps energy into them, including damaging the DNA).
Similarly, absorbing light is difficult as the higher frequencies require electronic and eventually nuclear transitions (this is the difference between x-rays and gamma rays) to actually absorb the photon. So scattering is the predominant energy absorption mechanism for biological interaction with gamma and x-rays.
chucklingmoose t1_iqtar1v wrote
I'll point out that eumelanin and pheomelanin in high concentration are always dark colors. I don't think I've heard of any melanin derivatives that are white... if there were, you've got a good point that they might work even better.
Avagpingham t1_iqtoaq1 wrote
I can't think of any protective quality melanin would have from ionizing radiation. It is more likely that some other protective trait is adjacent to the genes causing darker frogs or that a mutation causing darker frogs was triggered by the radiation and happens to be advantageous locally. (Nuclear engineer with minor in health physics and biology). However, I would be open to be corrected.
geon t1_iqux4s8 wrote
UV light is a form of ionizing radiation. That’s why melanin is a thing.
Not sure how effective it is against radioactive radiation.
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