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Melanin and genes

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Melanin is produced by cells called melanocytes in a process called melanogenesis. Melanin is made within small membrane–bound packages called melanosomes. As they become full of melanin, they move into the slender arms of melanocytes, from where they are transferred to the keratinocytes. Under normal conditions, melanosomes cover the upper part of the keratinocytes and protect them from genetic damage. One melanocyte supplies melanin to thirty-six keratinocytes according to signals from the keratinocytes. They also regulate melanin production and replication of melanocytes. People have different skin colors mainly because their melanocytes produce different amount and kinds of melanin. The genetic mechanism behind human skin color is mainly regulated by the enzyme tyrosinase, which creates the color of the skin, eyes, and hair shades. Differences in skin color are also attributed to differences in size and distribution of melanosomes in the skin. Melanocytes produce two types of melan...
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Exposure to the Sun

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Melanin in the skin protects the body by absorbing solar radiation. In general, the more melanin there is in the skin the more solar radiation can be absorbed. Excessive solar radiation causes direct and indirect DNA damage to the skin and the body naturally combats and seeks to repair the damage and protect the skin by creating and releasing further melanin into the skin's cells. With the production of the melanin, the skin color darkens, but can also cause sunburn. The tanning process can also be created by artificial UV radiation. There are two different mechanisms involved. Firstly, the UVA-radiation creates oxidative stress, which in turn oxidizes existing melanin and leads to rapid darkening of the melanin, also known as IPD (immediate pigment darkening). Secondly, there is an increase in production of melanin known as melanogenesis. Melanogenesis leads to delayed tanning and first becomes visible about 72 hours after exposure. The tan that is created by an increased melanoge...
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