Question

Frank has Klinefelter syndrome (47, XXY). His mother has normal skin, but his father has anhidrotic ectodermal dysplasia, an X-linked condition where the skin does not contain sweat glands. Frank has patches of normal skin and patches of skin without sweat glands. Which of the following options is correct? a. Frank received the mutant chromosome from his mother. Nondisjunction occurred in his mother during the second meiotic division b. Frank received the mutant chromosome from his father. Nondisjunction occurred in his father during the first meiotic division. c. Frank received the mutant chromosome from his father. Nondisjunction occurred in his father during the second meiotic division d. Frank received the mutant chromosome from his mother. Nondisjunction occurred in his mother during the first meiotic division. e. Frank received the mutant chromosome from his mother. Nondisjunction occurred in his father during the second meiotic division f. Frank received the mutant chromosome from his father. Nondisjunction occurred in his mother during the first meiotic division.

Answer 1

Answer:

b. Frank received the mutant chromosome from his father. Nondisjunction occurred in his father during the first meiotic division.

Explanation:

As you can see in the question above, Frank has Klinefelter syndrome which causes him to have normal skin patches and skin patches without sweat glands. Her mother has completely normal hair, which may indicate that the defective gene was not supplied by her. In addition, Frank's father has anhydrotic ectodermal dysplasia, an X-linked condition where the skin does not contain sweat glands.

Although Frank's father's defective gene is linked to the X chromosome, it is likely that Frank inherited the defective gene from his country. This may have occurred because during meiosis I, his father's genes did not show disjunction. As a result, Frank presents a mosaic of his phenotype, because an inactivation of the X chromosome occurred.