1. What was the factor that caused Steere to reach his conclusion?
  2. What is the disease?
  3. Why was the disease more prevalent between June and September?

2)  Newborn babies are tested for phenylketonuria (PKU), an inherited disease. Individuals with this disease are missing an enzyme to convert phenylalanine (Phe) to tyrosine; the resulting accumulation of Phe can cause mental retardation, brain damage, and seizures. The Guthrie test for PKU involves culturing Bacillus subtilis, which requires Phe to grow. The bacteria are grown on media with a drop of the baby’s blood.

  1. What type of chemical is phenylalanine?
  2. What does “no growth” in the Guthrie test mean?
  3. Why must individuals with PKU avoid the sweetener aspartame?