Question
Biology Question on Principles of Inheritance and Variation
Albinism is a congenital disorder resulting from the lack of which enzyme?
A
tyrosinase
B
xanthine oxidase
C
catalase
D
fructokinase.
Answer
tyrosinase
Explanation
Solution
Albinism is caused by the absence of the enzyme tyrosinase which is essential for the synthesis of the pigment from dihydroxy-phenyalanine. The gene for albinism (a) does not produce the enzyme tyrosinase but its normal allele (A) does. Thus, only homozygous individual (aa) is affected by this disease. Albinos (individuals with albinism) lack dark pigment melanin in the skin, hair and iris. Although albinos have poor vision yet they lead normal life. On the basis of principles of simple recessive inheritance, the probability of albinic child from a normally pigmented- parents, will be 1/4 or 25 %.