What enzyme do albino individuals lack that is crucial for melanin production?

Albino individuals lack the enzyme tyrosinase, which plays a crucial role in the production of melanin, the pigment responsible for coloration in the skin, hair, and eyes. Tyrosinase catalyzes the first two steps in the melanin biosynthetic pathway, converting the amino acid tyrosine into DOPA (dihydroxyphenylalanine) and then into DOPAquinone, which further leads to the formation of melanin. Without this enzyme, the entire process of melanin synthesis is disrupted, resulting in the characteristic lack of pigmentation seen in albinism.

The other options do not directly relate to the melanin production process. Melanase is not a recognized enzyme involved in this pathway, catalase mainly functions to break down hydrogen peroxide, and keratinase is involved in the breakdown of keratin, a structural protein found in skin and hair. Therefore, the absence of tyrosinase specifically explains the lack of melanin in albino individuals.