PKU Carriers

By David J. Grise

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.

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Date Posted

03/17/2011

Overview

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

Subject Headings

Biology (General)

Genetics / Heredity

Molecular Biology

EDUCATIONAL LEVEL

High school, Undergraduate lower division

FORMAT

PDF

TOPICAL AREAS

N/A

LANGUAGE

English

TYPE/METHODS

Interrupted

Teaching Notes & Answer Key

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