Answer:
Melanin is a protective pigment in skin, blocking UV radiation from damaging DNA and potentially causing skin cancer. Melanin does protect us, but this research shows it can also do us harm.
Definition:
UVA radiation causes lesions or DNA damage to melanocytes, which are the skin cells that produce the skin pigment known as melanin.
Explanation:
Melanin is a pigment that is produced by cells known as melanocytes in the skin of most animals, including humans. This pigment comes in different shades, depending on the genetic makeup of the individual. Melanin comes in two basic forms and can range from yellowish-red to dark brown. Eumelanin is the most common form of melanin and is brownish in color. The other basic form is called pheomelanin, which produces reddish-brown color that is often associated with freckles and red hair. The production of melanin in the individual is determined by several factors.
Genetically speaking, every individual on Earth has approximately the same number of melanocytes. The difference, then, in the production of melanin is affected by:
Exposure to UV radiation: Melanin is produced as a response to UV radiation in order to prevent damage to the DNA in the integument. Individuals, who are exposed to UV light, such as the sun, will produce more melanin for protection.
Genetic makeup: Different ethnicities and cultures are genetically pre-disposed to producing particular shades and amounts of melanin due to inheritance. This is, essentially, one of the primary indicators used in determining race in the human population. It is important to note that this is, and has historically been, a controversial form of human identification.
Size of melanocytes: Melanocyte size varies in different individuals and may lead to a difference in the amount of melanin produced per cell.
Disease conditions: Several diseases may affect melanin production, including albinism, a genetic inability to produce melanin, and vitiligo, a progressive loss of melanocytes.
