Lesson Plans for Educators

The Probabilities of Problems: A Look at Inheritance
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Estimated Time: 1-2 class periods

Introduction: Students learn how to calculate the the probabilities of passing on certain genetic disorders and then evaluate case studies involving genetic testing.

Lesson Objectives:
Students will:

• differentiate dominant, recessive and sex-linked forms of inheritance
• illustrate the probabilities of inheritance of four different genetic disorders
• assess the value of genetic testing in four case studies
• Internet access
• Case Study Worksheet
• Paper lunch sack for each student
• Colored poker chips or slips of paper.

1. Ask students how much they want to know about what they could pass on to their offspring. Is there such a thing as too much knowledge? Or should they be as informed as they possibly can? Discuss these ideas with the class then direct them to read the Making Better Babies" stories on the Our Genes/Our Choices Web site.

2. Explain to the students that parents pass traits to their offspring through their genes. Remind them that genes are located along bigger structures called chromosomes; each person has 46 of these, which are joined into 23 pairs. Each parent contributes one-half of each pair. It's how those genes work together that makes you unique. This activity illustrates how the genes from you mother and father can be recombined in their offspring and what the probabilities of passing on an inherited disorder might be.

3. Explain to students that they will be investigating four inherited disorders: Huntingdon's Disease, Fragile X Syndrome, Cystic Fibrosis, and Marfan's Syndrome. Information about the symptoms of each disease is included in the Real-Life Stories used at the beginning of the lesson; more detailed information may be found by following the links included here. Present a summary of each disease to the class, or ask them to access these Web sites directly.

4. For each case study, use colored poker chips (or slips of colored paper) to represent the different forms of the genes (dominant and recessive). Use a paper bag labeled Mother and one labeled Father to represent each parent.

5. Hand out the paper lunch sacks, chips and worksheets to each student. Have the students read through each case study and then complete the worksheet.

6. Compile the class results and discuss their answers to the questions.

Assessment Ideas:
Student understanding may be assessed through participation in class discussion and worksheet responses.

• Research the history of the genetic disorders described in this activity to find out how they were diagnosed and treated before current genetic testing procedures were available.
• Draw pedigree charts for the families in each case history studied.

Correlation to National Health Standards from http://www.aahperd.org/aahe/pdf_files/standards.pdf

1. HEALTH EDUCATION STANDARD 4:
Students will analyze the influence of culture, media, technology and other factors on health by analyzing the influence of technology on personal and family health.
2. HEALTH EDUCATION STANDARD 6:
Students will demonstrate the ability to use goal-setting and decision-making skills to enhance health by analyzing how health-related decisions are influenced by individuals, family, and community values.

Note: This lesson plan is also correlated to state science standards through the PBS TeacherSource Web site.

About the Author: Author Viki Babcock taught biology and physical science for 5 years at Hannibal High School in Hannibal, Missouri. She is currently teaching biology, zoology and botany at DeSoto High School in DeSoto, Missouri.