Chapter 10, Problem 4QP

Questions 4 through 6 refer to the following hypothetical pathway in which substance A is converted to substance C by enzymes 1 and 2. Substance B is the intermediate produced in this pathway:

a. If an individual is homozygous for a null mutation in the gene that codes for enzyme 1, what will the result be?

b. If an individual is homozygous for a null mutation in enzyme 2, what will the result be?

c. What if an individual is heterozygous for a dominant mutation in which enzyme 1 is overactive?

d. What if an individual is heterozygous for a mutation that abolishes the activity of enzyme 2 (a null mutation)?