This video explores the science behind melanin and skin pigmentation, discussing its biological significance and the factors influencing skin color.

What is the primary reason people develop a tan when exposed to sunlight?

• Increased DNA synthesis

• Increased activity of melanocytes

• Increased production of keratinocytes

• Decreased melanin production

Which enzyme is crucial for the conversion of tyrosine in the melanin biosynthetic pathway?

• Dopaminase

• Keratinase

• Tyrosinase

• Melanase

What is the direct precursor to both eumelanin and pheomelanin?

• DOPA quinone

• Indole quinone

• L-DOPA

• Dihydroxy indole

Which amino acid is incorporated into pheomelanin but not eumelanin?

• Serine

• Cysteine

• Glycine

• Tyrosine

What is the primary difference between eumelanin and pheomelanin?

• Pheomelanin is darker

• Eumelanin contains cysteine

• Eumelanin is red

• Pheomelanin contains cysteine

What determines the baseline level of melanin biosynthesis in individuals?

• Number of melanocytes

• Activity of melanocytes

• Amount of keratinocytes

• Presence of UV light

What condition results from a deficiency of the enzyme tyrosinase?

• Vitiligo

• Psoriasis

• Albinism

• Melanoma