Question

Melanin protects us from
A. X - rays
B. Infrared rays
C. Visible rays
D. UV rays

Answer 1

Hint: Melanin is a natural pigment derived by a multiple-stage biochemical process termed as melanogenesis, wherein the oxidation of tyrosine (amino acid) is succeeded by the polymerization process. Melanin pigments are developed in a specific category of cells called melanocytes.

Complete answer: Melanin is the major determinant of colour of skin in humans. It is present in the hair scalp, the pigmented tissues underneath the iris. Melanogenesis is triggered in human flesh by UV radiation, which makes the skin to darken. Melanin is an excellent absorber of light; this can dissipate more than 99.9 per cent of the Ultraviolet light captured by the pigment. This prohibits UV rays from entering the other vulnerable body cells and prevents potential damage to the DNA which could be done by them. That's why the body produces tanning once subjected to the direct sunlight. It is indeed a protective measure. Melanin is believed to protect the skin cells against UV-B radiation damage, reducing the impact of folate loss and dermal deterioration. Less melanin content is presumed to be linked to an increased risk of malignant skin cancer, melanocyte (melanin) cancer. Research findings have also shown a lower likelihood of skin cancer in people with more intense melanin, i.e. dark - skinned tones.
So, the correct answer is option D.

Additional information: Melanin is brown, finely granular with discrete granules of average diameter less than 800 nm. Dense mixtures of melanin can distort histopathologic analysis in extensively pigmented lesions. People whose descendants have existed for longer periods of time in the regions of the world closer to the equator have elevated amounts of melanin pigment in their skins. It makes their skin black or brown and defends them from extreme exposure to the sun, which would be more prone to cause melanoma in lighter-skinned populations.

Note: Melanocytes produce melanin granules onto specialized cell vesicles called melanosomes. These will be then distributed to mammalian epidermis keratinocyte cells. Melanosomes assemble at the peak of the nucleus of the cell in each host cell, guarding the nuclear DNA against mutations caused by ionising sunlight UV rays.