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PKU Carriers

How Many Are in Your Hometown?



Author:

David J. Grise

Oso Bay Educational Consulting
dave_grise@yahoo.com

Abstract:

In this interrupted case study, students read about a college student with phenylketonuria (PKU).  Students learn how diet affects a person with PKU and how PKU is inherited. The case is designed to introduce introductory biology students to the Hardy-Weinberg Principle. Terms of the equation are related to phenotypes and genotypes mentioned in the case. Given the number of people in the population with PKU and assuming the population is in Hardy-Weinberg Equilibrium, students estimate the number of carriers for PKU in the population. Finally, students estimate the probability that a person from this population with PKU would have a child with PKU and the probability that a person from this population without PKU would have a child with PKU.

Objectives:
  • Understand how a mathematical model can be used to address a biological question.
  • Review basic genetics covered in class to this point.
  • Understand that Hardy-Weinberg Equilibrium is a null hypothesis (there will be no change in allele or genotype frequencies if no evolutionary forces are acting on the population).
  • Learn what data need to be collected to use the Hardy- Weinberg equation to estimate frequency of carriers.
  • Be able to use the Hardy-Weinberg equation to calculate expected number of carriers.
Keywords: Hardy-Weinberg principle; inheritance; genotype frequency; carrier frequency; allele frequency; homozygous; heterozygous; population genetics; genetic disorder; phenylketonuria; PKU; phenylalanine; hydroxylase; PAH; gene mutation; founder effect
Topical Area: N/A
Educational Level: High school, Undergraduate lower division
Formats: PDF
Type/Method: Interrupted
Language: English
Subject Headings: Biology (General)   Genetics / Heredity   Molecular Biology  
Date Posted: 3/17/2011
Date Modified: N/A
Copyright: Copyright held by the National Center for Case Study Teaching in Science, University at Buffalo, State University of New York. Please see our usage guidelines, which outline our policy concerning permissible reproduction of this work.

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