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6 votes

Why does hair turn white but not skin?

The answer to this question has its reason in the hair cycle. Our hair goes through a cycle of growth. At the end of this cycle, the cells in the hair follicle die and have to be replenished before a ...
Chris's user avatar
  • 51.7k
6 votes
Accepted

Can cysteine alone change pigmentation?

Surprisingly, it is indeed possible! But, the fact is that the actual process is a bit more complex and might actually require more compounds along with cysteine to give such effects in living beings. ...
another 'Homo sapien''s user avatar
3 votes
Accepted

Toxicity of phaeomelanin

The paper in which Slater et al. reported preservation of phaeomelanin does not include the word or root ‘toxic’, so it is difficult to know whether the quotation is correct and, if so, what was ...
David's user avatar
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3 votes
Accepted

What decides between the synthesis of eumelanin and pheomelanin on a biochemical level?

Let's have a look at the pathway first (this figure is figure 2 from reference 1), which shows the basic pathway of pigment biosynthesis: The first important step, the oxidation of the amino acid ...
Chris's user avatar
  • 51.7k
2 votes

Does melanin protect against nuclear radiation?

The absorption of gamma and x-ray radiation by skin is negligible, so the amount of melanin present is irrelevant. Stopping high energy photons requires a lot of mass, not a few microns of melanin. ...
user1850479's user avatar
2 votes

Could being exposed to excess UV in the arctic lead to a human eye color change? If so, what is the mechanism?

It's a four year old question and so far nothing definitive, but the September 30, 2022 BBC Future article How our eyes can change colour throughout our lives includes the following quotes from David ...
uhoh's user avatar
  • 5,598
2 votes

Do any animals mix porphyrins and carotenoids in their pigmentation?

Yes. Here is one example of an annelid worm that does this: Altogether, the endogenous porphyrinoid pigments of E. viridis appear to be similar in function and origin to the coloured bile pigments of ...
Maximilian Press's user avatar
1 vote

Does melanin protect against nuclear radiation?

Ken Mac is correct, melanin has an effect and you should also consider fatty people to be the heroes of your scenario. Melanin can cause more surface burns compared to a person with light skin and ...
bandybabboon's user avatar
  • 10.4k
1 vote

Does melanin protect against nuclear radiation?

Maybe not much of an immediate advantage, but evolutionarily, I mean...according to the article below, the melanin in frogs with darker skin was enough to sway natural selection and drastically reduce ...
Ken Mac's user avatar
  • 11
1 vote

What kind melanin do fair or light skinned black or mixed people have, eumelanin of pheomelanin?

Pheomelanin is associated with paler skin, while eumelanin predomominates in people with darker skin — this is influenced by alleles of the MC1R gene Swope and Abdel-Malek, 2018, NIH article on MC1R.
tyersome's user avatar
  • 5,598
1 vote
Accepted

How does TYRP1 affect the synthesis of black and brown eumelanin (on a biochemical level)?

The actual coat color is determined by the ratio of the products of two genes: Tyr and TyrP1. The first oxidizes DHI to Indole-5,6-quinone and forms brown pigment, TyrP1 on the other hand oxidizes ...
Chris's user avatar
  • 51.7k
1 vote

Why Do Most Humans & Cats Have Blue/Bluish Eyes At Birth?

Mammals are born with blue eyes because the melanin level has not yet been established to give brown/yellow. Blue is the absence of melanin, so that eyes reflect outside light which is seen as blue. ...
Sonia Lee's user avatar
  • 281

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