PKU Webquest

PHENYLKETONURIA: A METABOLIC DISORDER

Metabolic disorders are genetic diseases that affect the body's ability to perform its normal chemical reactions. Many metabolic disorders result from enzyme defects. Recall that a metabolic pathway is a stepwise sequence of enzyme-mediated reactions. If one enzyme in a metabolic pathway is defective, that enzyme's substrate may accumulate and the pathway may not be completed. This may result in a buildup of harmful substances or a shortage of required molecules.

Activity

In this exercise, you will use the Web links below to gather information about the metabolic disorder phenylketonuria (PKU). Use what you learn to answer the questions at the bottom of the page.

Your Genes, Your Health: Phenylketonuria

http://www.ygyh.org

NSPKU Home Page

http://www.nspku.org

Baby’s First Test (Look up “Classic PKU”)

Newborn Screening in Colorado

Phenylketonuria - The Genetics

http://willroberts.com/pku/

Some possible questions for your research:

1. What enzyme is most commonly defective in people with phenylketonuria?

The enzyme that is most commonly defective in people with phenylketonuria is phenylalanine hydroxylalanine. This is needed to break down an essential amino acid called phenylalanine and foods that contain protein is where this substance is found.

2. What reaction does this enzyme catalyze? (What is the substrate and what product is produced?)
It actually breaks down phenylalanine into tyrosine.
 

3. Describe the symptoms of phenylketonuria.

The symptoms of phenylketonuria are dry, scaly skin (known as eczema), musty or mouse-like body odor, developmental delays, seizures (epilepsy), pale hair or skin, restlessness or fussiness, and smaller than a normal head.

4. What causes the symptoms of PKU, the lack of a substance or the buildup of one? Explain.
The lack of tyrosine causes a build up of PHe and the build of this in other parts puts a stop to the brain developing normally, this also adds to the other symptoms.

5. How common is phenylketonuria? How is it treated?

Phenylketonuria (PKU) appears in every one in ten thousand births. It is treated by being put on a low-protein diet for practically their whole lives